Spike-antibody waning after second dose of BNT162b2 or ChAdOx1

SIRS epidemics with individual heterogeneity of immunity waning

In the current paper we analyse an extended SIRS epidemic model in which immunity at the individual level wanes gradually at exponential rate, but where the waning rate may differ between individuals, for instance as an effect of differences in immune systems. The model also includes vaccination schemes aimed to reach and maintain herd immunity. We consider both the informed situation where the individual waning parameters are known, thus allowing selection of vaccinees being based on both time since last vaccination as well as on the individual waning rate, and the more likely uninformed situation where individual waning parameters are unobserved, thus only allowing vaccination schemes to depend on time since last vaccination. The optimal vaccination policies for both the informed and uniformed heterogeneous situation are derived and compared with the homogeneous waning model (meaning all individuals have the same immunity waning rate), as well as to the classic SIRS model where immunity at the individual level drops from complete immunity to complete susceptibility in one leap. It is shown that the classic SIRS model requires least vaccines, followed by the SIRS with homogeneous gradual waning, followed by the informed situation for the model with heterogeneous gradual waning. The situation requiring most vaccines for herd immunity is the most likely scenario, that immunity wanes gradually with unobserved individual heterogeneity. For parameter values chosen to mimic COVID-19 and assuming perfect initial immunity and cumulative immunity of 12 months, the classic homogeneous SIRS epidemic suggests that vaccinating individuals every 15 months is sufficient to reach and maintain herd immunity, whereas the uninformed case for exponential waning with rate heterogeneity corresponding to a coefficient of variation being 0.5, requires that individuals instead need to be vaccinated every 4.4 months.

Polyvalent mpox mRNA vaccines elicit robust immune responses and confer potent protection against vaccinia virus

The 2022 mpox outbreak led the World Health Organization (WHO) to declare it a public health emergency of international concern (PHEIC). There is a need to develop more effective and safer mpox virus (MPXV)-specific vaccines in response to the mpox epidemic. The mRNA vaccine is a promising platform to protect against MPXV infection. In this study, we construct two bivalent MPXV mRNA vaccines, designated LBA (B6R-A29L) and LAM (A35R-M1R), and a quadrivalent mRNA vaccine, LBAAM (B6R-A35R-A29L-M1R). The immunogenicity and protective efficacy of these vaccines alone or in combination were evaluated in a lethal mouse model. All mRNA vaccine candidates could elicit potential antigen-specific humoral and cellular immune responses and provide protection against vaccinia virus (VACV) infection. The protective effect of the combination of two bivalent mRNA vaccines and the quadrivalent vaccine was superior to that of the individual bivalent mRNA vaccine. Our study provides valuable insights for the development of more efficient and safer mRNA vaccines against mpox.

Antibody longevity and waning following COVID-19 vaccination in a 1-year longitudinal cohort in Bangladesh

COVID-19 vaccines have been effective in preventing severe illness, hospitalization and death, however, the effectiveness diminishes with time. Here, we evaluated the longevity of antibodies generated by COIVD-19 vaccines and the risk of (re)infection in Bangladeshi population. Adults receiving two doses of AstraZeneca, Pfizer, Moderna or Sinopharm vaccines were enrolled at 2-4 weeks after second dosing and followed-up at 4-monthly interval for 1 year. Data on COVID-like symptoms, confirmed COVID-19 infection, co-morbidities, and receipt of booster dose were collected; blood was collected for measuring spike (S)- and nucleocapsid (N)-specific antibodies. S-specific antibody titers reduced by ~ 50% at 1st follow-up visit and continued to decline unless re-stimulated by booster vaccine dose or (re)infection. Individuals infected between follow-up visits showed significantly lower S-antibody titers at preceding visits compared to the uninfected individuals. Pre-enrolment infection between primary vaccination dosing exhibited 60% and 50% protection against reinfection at 5 and 9 months, respectively. mRNA vaccines provided highest odds of protection from (re)infection up to 5 months (Odds Ratio (OR) = 0.08), however, protection persisted for 9 months in AstraZeneca vaccine recipients (OR = 0.06). In conclusion, vaccine-mediated protection from (re)infection is partially linked to elevated levels of S-specific antibodies. AstraZeneca vaccine provided the longest protection.

SARS-CoV-2-Specific Antibodies, B Cell and T Cell Immune Responses after ChAdOx1 nCoV-19 Vaccination in Solid Organ Transplant Recipients

BACKGROUND

Immunization against SARS-CoV-2 is essential for vulnerable solid organ transplant (SOT) recipients who are at risk of infection. However, there are concerns about suboptimal immunogenicity, especially in humoral immunity (HMI), and limited exploration of cell-mediated immune (CMI) responses. The primary objective of this study was to assess the immunogenicity of ChAdOx1 nCoV-19 vaccination in SOT recipients. The secondary endpoint was to evaluate factors that affect immunogenicity and adverse events (AEs) following immunization in SOT recipients.

METHODS

All adult SOT recipients who received the two-dose ChAdOx1 nCoV-19 vaccine at a 12-week interval underwent measurements of HMI by evaluating anti-receptor-binding domain (RBD) IgG levels and CMI by investigating SARS-CoV-2-specific T cell and B cell responses before and after complete vaccination, around 2-4 weeks post-vaccination, and compared to controls. AEs were monitored in all participants.

RESULTS

The study included 63 SOT recipients: 44 kidney recipients, 16 liver recipients, and 3 heart transplant recipients, along with 11 immunocompetent controls. Among SOT recipients, 36% were female, and the median (IQR) age was 52 (42-61). The median (IQR) time since transplant was 55 (28-123) months. After the second dose, the median (IQR) anti-RBD antibody levels were significantly lower in SOT recipients compared to those in the control group (8.3 [0.4-46.0] vs. 272.2 [178.1-551.6] BAU/mL, p < 0.01). This resulted in a seroconversion rate (anti-RBD antibody > 7.1 BAU/mL) of 51% among SOT recipients and 100% among controls (p = 0.008). Receiving the vaccine beyond one year post-transplant significantly affected seroconversion (OR 9.04, 95% CI 1.04-78.56, p = 0.046), and low-dose mycophenolic acid marginally affected seroconversion (OR 2.67, 95% CI 0.89-7.96, p = 0.079). RBD-specific B cell responses were also significantly lower compared to those in the control group (0 [0-4] vs. 10 [6-22] SFUs/106 PBMCs, p = 0.001). Similarly, S1- and SNMO-specific T cell responses were significantly lower compared to those in the control group (48 [16-128] vs. 216 [132-356] SFUs/106 PBMCs, p = 0.004 and 20 [4-48] vs. 92 [72-320] SFUs/106 PBMCs, p = 0.004). AEs were generally mild and spontaneously resolved.

CONCLUSIONS

SOT recipients who received the full two-dose ChAdOx1 nCoV-19 vaccine demonstrated significantly diminished HMI and CMI responses compared to immunocompetent individuals. Consideration should be given to administering additional vaccine doses or optimizing immunosuppressant regimens during vaccination (Thai Clinical Trial Registry: TCTR20210523002).

The continuance intention to vaccinate against COVID-19: An empirical study from Malaysia

BACKGROUND

Vaccination has been one of the most effective preventive strategies to contain the COVID-19 pandemic. However, as the COVID-19 vaccines' effect wanes off after some time and given their reduced level of protection against mutation strains of the virus, the calls for boosters and second boosters signal the need for continuous vaccination for the foreseeable future. As Malaysia transitions into the endemic phase, the nation's ability to co-exist with the virus in the endemic phase will hinge on people's continuance intention to be vaccinated against the virus. Adapting the expectations confirmation model (ECM) to the public health context and in a developing country, this study integrates the ECM with the health belief model (HBM) and the theory of reasoned action (TRA) to examine the inter-relationships of the predictors of people's continuance intention to vaccinate against COVID-19.

METHODOLOGY

Data were collected using self-administered questionnaires from 1,914 respondents aged 18 and above by a marketing consulting firm via its online panel. The partial least squares structural equation modeling (PLS-SEM) technique was used to analyze the data.

RESULTS

Out of the 1,914 respondents, 55.9% reported having a continuance intention to vaccinate against COVID-19, similar to other developing countries. The multivariate analysis revealed that perceived usefulness and satisfaction significantly influenced individuals' continuance intention to vaccinate against COVID-19. Additionally, attitude was found to play a key role in influencing behavioral change among individuals towards their perceptions of continuously getting vaccinated against COVID-19.

CONCLUSIONS

By integrating three theoretical frameworks (i.e., HBM, TRA and ECM), this study showed that behavioral characteristics could provide insights towards continuance vaccination intention. Hence, policymakers and key stakeholders can develop effective public health strategies or interventions to encourage vaccine booster uptake by targeting behavioral factors such as perceived usefulness, attitude, satisfaction, and subjective norms.

Disparities and Outcomes in the First and Second Year of the Pandemic on Events of Acute Myocardial Infarction in Coronavirus Disease 2019 Patients

Background and Objectives: Coronavirus disease 2019 (COVID-19) caused several cardiovascular complications, including acute myocardial infarction (AMI), in infected patients. This study aims to understand the overall trends of AMI among COVID-19 patients during the first two years of the pandemic and the disparities and outcomes between the first and second years. Materials and Methods: The retrospective analysis was conducted via the 2020 and 2021 National Inpatient Sample (NIS) database for hospitalizations between April 2020 and December 2021 being analyzed for adults with a primary diagnosis of COVID-19 who experienced events of AMI. A comparison of month-to-month events of AMI and mortality of AMI patients with concomitant COVID-19 was made alongside their respective patient characteristics. Results: Out of 2,541,992 COVID-19 hospitalized patients, 3.55% experienced AMI. The highest rate of AMI was in December 2021 (4.35%). No statistical differences in trends of AMI mortality were noted over the 21 months. AMI cases in 2021 had higher odds of undergoing PCI (aOR 1.627, p < 0.01). They experienced higher risks of acute kidney injury (aOR 1.078, p < 0.01), acute ischemic stroke (aOR 1.215, p < 0.01), cardiac arrest (aOR 1.106, p < 0.01), need for mechanical ventilation (aOR 1.133, p < 0.01), and all-cause mortality (aOR 1.032, 95% CI 1.001-1.064, p = 0.043). Conclusions: The incidence of AMI among COVID-19 patients fluctuated over the 21 months of this study, with a peak in December 2021. COVID-19 patients reporting AMI in 2021 experienced higher overall odds of multiple complications, which could relate to the exhaustive burden of the pandemic in 2021 on healthcare, the changing impact of the virus variants, and the hesitancy of infected patients to seek care.

Immunogenicity and safety of COVID-19 booster vaccination: A population-based clinical trial to identify the best vaccination strategy

BACKGROUND

Various SARS-CoV-2 variants of concerns (VOCs) characterized by higher transmissibility and immune evasion have emerged. Despite reduced vaccine efficacy against VOCs, currently available vaccines provide protection. Population-based evidence on the humoral immune response after booster vaccination is crucial to guide future vaccination strategies and in preparation for imminent COVID-19 waves.

METHODS

This multicenter, population-based cohort study included 4697 individuals ≥18 years of age who received a booster vaccination. Antibody levels against SARS-CoV-2 receptor binding domain (RBD) and neutralizing antibodies against wild-type (WT) virus and Omicron variants were assessed at baseline (day of booster vaccination) and after four weeks. Safety was evaluated daily within the first week using a participant-completed electronic diary. Antibody levels were compared across different vaccination strategies, taking into account individual host factors.

RESULTS

Our main model including 3838 participants revealed that individuals who received a booster with mRNA-1273 compared to BNT162b2 vaccine had a significantly higher increase (95 %CI) in anti-RBD-antibody levels (37,707 BAU/mL [34,575-40,839] vs. 27,176 BAU/mL [26,265-28,087]), and of neutralization levels against WT (1,681 [1490-1872] vs. 1141 [1004-1278] and Omicron variant (422 [369-474] vs. 329 [284-374]). Neutralizing antibody titres highly correlated with anti-RBD antibodies, with neutralizing capacity 4.4 fold higher against WT compared to Omicron. No differences in safety were found between the two booster vaccines.

CONCLUSION

Our study underlines the superiority of a booster vaccination with mRNA-1273, independent of the primary vaccination and therefore provides guidance on the vaccination strategy.

Demographic and Clinical Factors Associated With SARS-CoV-2 Spike 1 Antibody Response Among Vaccinated US Adults: the C4R Study

This study investigates correlates of anti-S1 antibody response following COVID-19 vaccination in a U.S. population-based meta-cohort of adults participating in longstanding NIH-funded cohort studies. Anti-S1 antibodies were measured from dried blood spots collected between February 2021-August 2022 using Luminex-based microsphere immunoassays. Of 6245 participants, mean age was 73 years (range, 21-100), 58% were female, and 76% were non-Hispanic White. Nearly 52% of participants received the BNT162b2 vaccine and 48% received the mRNA-1273 vaccine. Lower anti-S1 antibody levels are associated with age of 65 years or older, male sex, higher body mass index, smoking, diabetes, COPD and receipt of BNT16b2 vaccine (vs mRNA-1273). Participants with a prior infection, particularly those with a history of hospitalized illness, have higher anti-S1 antibody levels. These results suggest that adults with certain socio-demographic and clinical characteristics may have less robust antibody responses to COVID-19 vaccination and could be prioritized for more frequent re-vaccination.

A single-dose MCMV-based vaccine elicits long-lasting immune protection in mice against distinct SARS-CoV-2 variants

Current vaccines against COVID-19 elicit immune responses that are overall strong but wane rapidly. As a consequence, the necessary booster shots have led to vaccine fatigue. Hence, vaccines that would provide lasting protection against COVID-19 are needed, but are still unavailable. Cytomegaloviruses (CMV) elicit lasting and uniquely strong immune responses. Used as vaccine vectors, they may be attractive tools that obviate the need for boosters. Therefore, we tested the murine CMV (MCMV) as a vaccine vector against COVID-19 in relevant preclinical models of immunization and challenge. We have previously developed a recombinant murine CMV (MCMV) vaccine vector expressing the spike protein of the ancestral SARS-CoV-2 (MCMVS). In this study, we show that the MCMVS elicits a robust and lasting protection in young and aged mice. Notably, S-specific humoral and cellular immunity was not only maintained but even increased over a period of at least 6 months. During that time, antibody avidity continuously increased and expanded in breadth, resulting in neutralization of genetically distant variants, like Omicron BA.1. A single dose of MCMVS conferred rapid virus clearance upon challenge. Moreover, MCMVS vaccination controlled two immune-evading variants of concern (VoCs), the Beta (B.1.135) and the Omicron (BA.1) variants. Thus, CMV vectors provide unique advantages over other vaccine technologies, eliciting broadly reactive and long-lasting immune responses against COVID-19.

IgG responses against SARS-CoV-2 vaccines AZD1222 and BBV-152 and breakthrough infections among health care workers in southern India

IgG antibodies elicited in response to SARS-CoV-2 are critical in determining the protection achieved through vaccination. The present longitudinal study aims to assess the immune response generated through AZD1222 & BBV-152 vaccination among health care workers (HCWs) in a selected hospital. Serum IgG levels were measured approximately at 1.5 months and 6 months after the first and second vaccination. The final assessment was done 12 months after the first vaccination to analyse the sustained antibody levels. Results showed a progressive increase in antibody titres as a function of time. 26 HCWs in all had SARS-CoV-2 breakthrough infection, but their antibody titres were not significantly higher compared to COVID-19 naïve individuals. However, a comparative analysis showed considerably higher antibody titre in those who received the AZD1222 vaccine among this cohort. AZD1222 vaccination was significantly associated with seropositivity in the first and second assessments. Female HCWs showed significantly higher seropositivity, and participants above 60 years showed considerably reduced antibody titre in the first assessment. However, the final assessment showed no association with these variables, with 97.1 % of participants reporting to be seropositive. The results indicate good antibody response and potential protection against SARS CoV-2.

Effectiveness of mRNA Booster Vaccine Against Coronavirus Disease 2019 Infection and Severe Outcomes Among Persons With and Without Immune Dysfunction: A Retrospective Cohort Study of National Electronic Medical Record Data in the United States

Background

Real-world evidence of coronavirus disease 2019 (COVID-19) messenger RNA (mRNA) booster effectiveness among patients with immune dysfunction are limited.

Methods

We included data from patients in the United States National COVID Cohort Collaborative (N3C) who completed ≥2 doses of mRNA vaccination between 10 December 2020 and 27 May 2022. Immune dysfunction conditions included human immunodeficiency virus infection, solid organ or bone marrow transplant, autoimmune diseases, and cancer. We defined incident COVID-19 BTI as positive results from laboratory tests or diagnostic codes 14 days after at least 2 doses of mRNA vaccination; and severe COVID-19 BTI as hospitalization, invasive cardiopulmonary support, and/or death. We used propensity scores to match boosted versus nonboosted patients and evaluated hazards of incident and severe COVID-19 BTI using Cox regression after matching.

Results

Among patients without immune dysfunction, the relative effectiveness of booster (3 doses) after 6 months from the primary (2 doses) vaccination against BTI ranged from 69% to 81% during the Delta-predominant period and from 33% to 39% during the Omicron-predominant period. Relative effectiveness against BTI was lower among patients with immune dysfunction but remained statistically significant in both periods. Boosted patients had lower risk of COVID-19-related hospitalization (hazard ratios [HR] ranged from 0.5 [95% confidence interval {CI}, .48-.53] to 0.63 [95% CI, .56-.70]), invasive cardiopulmonary support, or death (HRs ranged from 0.46 [95% CI, .41-.52] to 0.63 [95% CI, .50-.79]) during both periods.

Conclusions

Booster vaccines remain effective against severe COVID-19 BTI throughout the Delta- and Omicron-predominant periods, regardless of patients' immune status.

Caveats of chimpanzee ChAdOx1 adenovirus-vectored vaccines to boost anti-SARS-CoV-2 protective immunity in mice

Several COVID-19 vaccines use adenovirus vectors to deliver the SARS-CoV-2 spike (S) protein. Immunization with these vaccines promotes immunity against the S protein, but against also the adenovirus itself. This could interfere with the entry of the vaccine into the cell, reducing its efficacy. Herein, we evaluate the efficiency of an adenovirus-vectored vaccine (chimpanzee ChAdOx1 adenovirus, AZD1222) in boosting the specific immunity compared to that induced by a recombinant receptor-binding domain (RBD)-based vaccine without viral vector. Mice immunized with the AZD1222 human vaccine were given a booster 6 months later, with either the homologous vaccine or a recombinant vaccine based on RBD of the delta variant, which was prevalent at the start of this study. A significant increase in anti-RBD antibody levels was observed in rRBD-boosted mice (31-61%) compared to those receiving two doses of AZD1222 (0%). Significantly higher rates of PepMix™- or RBD-elicited proliferation were also observed in IFNγ-producing CD4 and CD8 cells from mice boosted with one or two doses of RBD, respectively. The lower efficiency of the ChAdOx1-S vaccine in boosting specific immunity could be the result of a pre-existing anti-vector immunity, induced by increased levels of anti-adenovirus antibodies found both in mice and humans. Taken together, these results point to the importance of avoiding the recurrent use of the same adenovirus vector in individuals with immunity and memory against them. It also illustrates the disadvantages of ChAdOx1 adenovirus-vectored vaccine with respect to recombinant protein vaccines, which can be used without restriction in vaccine-booster programs. KEY POINTS: • ChAdOx1 adenovirus vaccine (AZD1222) may not be effective in boosting anti-SARS-CoV-2 immunity • A recombinant RBD protein vaccine is effective in boosting anti-SARS-CoV-2 immunity in mice • Antibodies elicited by the rRBD-delta vaccine persisted for up to 3 months in mice.

Ipsilateral immunization after a prior SARS-CoV-2 mRNA vaccination elicits superior B cell responses compared to contralateral immunization

mRNA vaccines have proven to be pivotal in the fight against COVID-19. A recommended booster, given 3 to 4 weeks post the initial vaccination, can substantially amplify protective antibody levels. Here, we show that, compared to contralateral boost, ipsilateral boost of the SARS-CoV-2 mRNA vaccine induces more germinal center B cells (GCBCs) specific to the receptor binding domain (RBD) and generates more bone marrow plasma cells. Ipsilateral boost can more rapidly generate high-affinity RBD-specific antibodies with improved cross-reactivity to the Omicron variant. Mechanistically, the ipsilateral boost promotes the positive selection and plasma cell differentiation of pre-existing GCBCs from the prior vaccination, associated with the expansion of T follicular helper cells. Furthermore, we show that ipsilateral immunization with an unrelated antigen after a prior mRNA vaccination enhances the germinal center and antibody responses to the new antigen compared to contralateral immunization. These findings propose feasible approaches to optimize vaccine effectiveness.

Nanovaccines for Advancing Long-Lasting Immunity against Infectious Diseases

Infectious diseases, particularly life-threatening pathogens such as small pox and influenza, have substantial implications on public health and global economies. Vaccination is a key approach to combat existing and emerging pathogens. Immunological memory is an essential characteristic used to evaluate vaccine efficacy and durability and the basis for the long-term effects of vaccines in protecting against future infections; however, optimizing the potency, improving the quality, and enhancing the durability of immune responses remains challenging and a focus for research involving investigation of nanovaccine technologies. In this review, we describe how nanovaccines can address the challenges for conventional vaccines in stimulating adaptive immune memory responses to protect against reinfection. We discuss protein and nonprotein nanoparticles as useful antigen platforms, including those with highly ordered and repetitive antigen array presentation to enhance immunogenicity through cross-linking with multiple B cell receptors, and with a focus on antigen properties. In addition, we describe how nanoadjuvants can improve immune responses by providing enhanced access to lymph nodes, lymphnode targeting, germinal center retention, and long-lasting immune response generation. Nanotechnology has the advantage to facilitate vaccine induction of long-lasting immunity against infectious diseases, now and in the future.

Ginseng Polysaccharide Enhances the Humoral and Cellular Immune Responses to SARS-CoV-2 RBD Protein Subunit Vaccines

The COVID-19 pandemic remarkably accelerated vaccine research progress. The role of adjuvants in enhancing vaccine immune intensity and influencing immune types has been considered. Ginseng polysaccharide (GPS) has been demonstrated to have strong immunoregulatory properties. It is important to explore the feasibility of adding GPS to vaccine adjuvant components to improve the immune response effect of RBD vaccines. Here, we prepared a SARS-CoV-2 RBD antigen using the Escherichia coli expression system and determined that subcutaneous administration of GPS at a dose of 40 mg/kg could effectively activate dendritic cells (DCs) and macrophages (MΦ) in mice. Compared with the RBD group, the RBD+GPS triggered stronger and persistent antibody responses. It is also notable that higher levels of RBD-specific IgG and IgA were distributed in the lungs of RBD+GPS-immunized BALB/c mice. In addition, the RBD+GPS also resulted in lower percentages of IFN-γ+ CD4+ T cells and higher percentages of IFN-γ+ CD8+ T cells and CD8+ Tcm cells. These results suggest that GPS could be a promising vaccine immuno-enhancer for SARS-CoV-2 RBD subunit vaccines to establish stronger systemic and pulmonary mucosal protective immunity.

Analysis of humoral and cellular immunity after SARS-CoV-2 vaccination in patients with multiple sclerosis treated with immunomodulatory drugs

We analyzed immune response to SARS-CoV-2 vaccination by measuring specific IgG titers and T-cell reactivity to different SARS-CoV-2 peptides in multiple sclerosis patients taking different disease-modifying treatments. Of the 88 patients included, 72 developed any kind of immune response after vaccination. Although DMTs such as fingolimod and anti-CD20+ treatments prevented patients from developing a robust humoral response to the vaccine, most of them were still able to develop a cellular response, which could be crucial for long-term immunity. It is probably advisable that all MS patients take additional/booster doses to increase their humoral and/or cellular immune response to SARS-CoV-2.

A receptor-binding domain-based nanoparticle vaccine elicits durable neutralizing antibody responses against SARS-CoV-2 and variants of concern

Numerous vaccines have been developed to address the current COVID-19 pandemic, but safety, cross-neutralizing efficacy, and long-term protectivity of currently approved vaccines are still important issues. In this study, we developed a subunit vaccine, ASD254, by using a nanoparticle vaccine platform to encapsulate the SARS-CoV-2 spike receptor-binding domain (RBD) protein. As compared with the aluminum-adjuvant RBD vaccine, ASD254 induced higher titers of RBD-specific antibodies and generated 10- to 30-fold more neutralizing antibodies. Mice vaccinated with ASD254 showed protective immune responses against SARS-CoV-2 challenge, with undetectable infectious viral loads and reduced typical lesions in lung. Besides, neutralizing antibodies in vaccinated mice lasted for at least one year and were effective against various SARS-CoV-2 variants of concern, including B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.617.2 (Delta), and B.1.1.529 (Omicron). Furthermore, particle size, polydispersity index, and zeta-potential of ASD254 remained stable after 8-month storage at 4°C. Thus, ASD254 is a promising nanoparticle vaccine with good immunogenicity and stability to be developed as an effective vaccine option in controlling upcoming waves of COVID-19.

Immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in patients receiving secukinumab: a literature review

Purpose: There is a paucity of evidence on the impact of immune-mediated inflammatory disease (IMID) treatments on the immunogenicity of SARS-CoV-2 vaccination. The purpose of this literature review is to address the question of whether patients with IMIDs receiving secukinumab, a fully human anti-interleukin-17A monoclonal antibody, have an adequate immune response after SARS-CoV-2 vaccination. Materials and Methods: Clinical studies that evaluated the effect of secukinumab on immune responses in patients with IMIDs after SARS-CoV-2 vaccination were searched in publication databases, including Medline and Embase, until May 2022. Results: From the 53 articles identified, a total of 11 articles were included. Overall, the majority of the patients treated with secukinumab elicited an adequate immune response to SARS-CoV-2 vaccines. Patients receiving secukinumab for IMIDs developed cellular immune responses following vaccination with the BNT162b2 vaccine, and there were no significant differences in the overall humoral and cellular immune responses between patients and healthy individuals. The third dose of the BNT162b2 mRNA vaccine resulted in a positive antibody response in secukinumab-treated patients. Conclusion: The available data provide no evidence of impairment in immunological response to SARS-CoV-2 vaccines by secukinumab in patients with IMIDs.

Antibody responses after BNT162b2 vaccination in Japanese geriatric intermediate care facilities

Background

To evaluate antibody responses against the primary series of vaccination of severe acute respiratory syndrome coronavirus-2 [SARS-CoV-2] vaccines in the staff and residents of Japanese geriatric intermediate care facilities.

Methods

All subjects (159 staff and 96 residents) received two doses of the BNT162b2 mRNA vaccine 3 weeks apart. Baseline data of subject were collected using a structured form. Serum samples were collected three times: before vaccination, 3 weeks after the first dose, and 4 weeks after the second dose, and anti-receptor binding domain of the spike protein of SARS-CoV-2 [anti-RBD] IgG was measured using two immunoassays.

Results

After the second dose, geometric mean titers [GMT] of anti-RBD with both the Abbott and Roche assay were significantly lower in residents than staff (2282 AU/mL vs. 8505 AU/mL, and 258 U/mL vs. 948 U/mL, respectively). Multivariate analysis of characteristics affecting antibody responses (≥1280 AU/mL for Abbott and > 210 U/mL for Roche) showed lower odds ratios [ORs] for older age (adjusted OR per 10 year increase [aOR] = 0.62, 95 % confidence interval [95 %CI]; 0.38-1.02), steroid usage (aOR = 0.09, 95 %CI; 0.01-0.60) and regular nonsteroidal anti-inflammatory drugs [NSAIDs] usage (aOR = 0.16, 95 %CI; 0.03-0.88).

Conclusions

Elderly people and steroid and NSAID users had lower antibody responses following the second vaccine dose.

BNT162b2 Booster Dose Elicits a Robust Antibody Response in Subjects with Abdominal Obesity and Previous SARS-CoV-2 Infection

Little is known about the long-term durability of the induced immune response in subjects with obesity, particularly in those with an abdominal distribution of adipose tissue. We evaluated SARS-CoV-2-specific antibody responses after BNT162b2 vaccine booster dose, comparing individuals with and without abdominal obesity (AO), discerning between individuals previously infected or not. IgG-TrimericS were measured in 511 subjects at baseline, on the 21st day after vaccine dose 1, and at 1, 3, 6, and 9 months from dose 2, and at 1 and 3 months following the booster dose. To detect SARS-CoV-2 infection, nucleocapsid antibodies were measured at baseline and at the end of the study. Multivariable linear regression evaluated the three-month difference in the absolute variation in IgG-TrimericS levels from booster dose, showing AO and SARS-CoV-2 infection status interactions (p = 0.016). Regardless of possible confounding factors and IgG-TrimericS levels at the booster dose, AO is associated with a higher absolute change in IgG-TrimericS in prior infected individuals (p = 0.0125). In the same regression model, no interaction is highlighted using BMI (p = 0.418). The robust response in the development of antibodies after booster dose, observed in people with AO and previous infection, may support the recommendations to administer a booster dose in this population group.

Dose Intervals and Time since Final Dose on Changes in Metabolic Indices after COVID-19 Vaccination

The rapid development and implementation of COVID-19 vaccines merit understanding its effects on metabolic indices. This retrospective longitudinal study investigated the influence of first-to-second-dose intervals and time since the final dose on the metabolic indices of individuals receiving COVID-19 vaccinations. A total of 318 Saudi subjects (59.7% females) aged 12-60 years received COVID-19 vaccines via the national vaccination program. We collected the anthropometric data and fasting blood samples at specific time points before vaccination and after the final vaccination dose, and biochemical metabolic indices, including glucose and lipid profile, were measured. We also collected the dates of vaccination and COVID-19 history during the study period. The participants were stratified into groups based on first-to-second-dose intervals and time since the final dose to compare pre-and post-vaccination changes in metabolic indices between the groups. Logistic regression analysis revealed no differences in pre- to post-vaccination metabolic status between groups based on first-to-second-dose intervals in either adolescents or adults. However, shorter intervals (≤6 months) between the final dose and follow-up were associated with a decrease in total cardiometabolic components, especially triglyceride levels (OR = 0.39, 95% CI: (0.22-0.68), p < 0.001) than longer intervals (>6 months) in adults. In conclusion, time duration since final dose was associated with pre- to post-vaccination changes in metabolic indices, especially triglyceride levels, indicating that post-vaccination improvements wane over time. Further research is needed to validate the observed relationship, as it may contribute to optimizing vaccine effectiveness and safety in the future.

Comparing the recurrence of audio-vestibular disorders following breakthrough infection of COVID-19 vs. those following vaccine administration

PURPOSE

The term "breakthrough infection" of COVID-19 indicates that subjects who previously received COVID-19 vaccination became infected with COVID-19. This study compared the recurrence of audio-vestibular disorders following breakthrough infection of COVID-19 vs. those following vaccine administration.

PATIENTS AND METHODS

Fifty patients with previous known audio-vestibular disorders visited our clinic due to recurrence of inner ear symptoms following breakthrough infection of COVID-19 and were assigned to Group A. Another 50 patients who had recurrent inner ear symptoms following COVID-19 vaccination were assigned to Group B for comparison. The post-breakthrough infection interval is defined from date of breakthrough infection to the onset of inner ear symptoms, while the post-vaccination interval means the time from date of vaccination to the onset of inner ear symptoms. These two intervals were calculated and then compared.

RESULTS

The time from latest vaccination to the breakthrough infection of COVID-19 was 4 m (median), likely due to waning of IgG response. To the onset of inner ear symptoms, the post-breakthrough infection interval was 40d (median) for Group A, which was significantly longer than 10d (median) of the post-vaccination interval for Group B.

CONCLUSION

The post-breakthrough infection interval (median, 40d) is significantly longer than the post-vaccination interval (median, 10d) to exacerbate pre-existing audio-vestibular disorders. The reason is probably because an interval of 40d is related to IgG peak response following COVID-19 breakthrough infection, while that of 10d is responsible for IgG production after COVID-19 vaccination.

Broad and potent neutralizing antibodies are elicited in vaccinated individuals following Delta/BA.1 breakthrough infection

IMPORTANCE

With the emergence of SARS-CoV-2 viral variants, there has been an increase in infections in vaccinated individuals. Here, we isolated monoclonal antibodies (mAbs) from individuals experiencing a breakthrough infection (Delta or BA.1) to determine how exposure to a heterologous Spike broadens the neutralizing antibody response at the monoclonal level. All mAbs isolated had reactivity to the Spike of the vaccine and infection variant. While many mAbs showed reduced neutralization of current circulating variants, we identified mAbs with broad and potent neutralization of BA.2.75.2, XBB, XBB.1.5, and BQ.1.1 indicating the presence of conserved epitopes on Spike. These results indicate that variant-based vaccine boosters have the potential to broaden the vaccine response.

Factors Affecting SARS-CoV-2 IgG Production after Vaccination and/or Disease: A Large-Scale Seroprevalence Study

This study aimed at identifying factors influencing SARS-CoV-2-specific IgG antibody levels after vaccination and/or infection. Between January 2022 and March 2023, 2000 adults (≥18 years, Salzburg, Austria) participated in this population-based seroprevalence study by providing 3 mL of blood to detect SARS-CoV-2-specific IgG antibodies using an anti-SARS-CoV-2 IgG quantitative assay and by completing a self-designed questionnaire including anthropometric factors, vaccination information, and medical history. For 77 of the participants, a time-course study up to 24 weeks post vaccination or quarantine end was performed. Convalescent-only subjects had the lowest median antibody titer (65.6 BAU/mL) compared to vaccinated and hybrid immunized subjects (p-value < 0.0001) The type of vaccine as well as vaccine combinations significantly influenced the levels of SARS-CoV-2 spike-protein-specific IgG, ranging from a median antibody level of 770.5 BAU/mL in subjects who were vaccinated only to 3020.0 BAU/mL in hybrid immunized subjects (p-value < 0.0001). Over time, a significant decline in the levels of neutralizing antibodies was found. Depending on the subpopulation analyzed, further significant influencing factors included sex assigned at birth, disease severity, chronic diseases, and medication. A hybrid immunization resulted in more robust immune responses. Nevertheless, there were multiple other factors impacting these responses. This knowledge should be included in future vaccination strategies and serve as a guide in the development of personalized medicine.

Humoral and cellular immune responses in fully vaccinated individuals with or without SARS-CoV-2 breakthrough infection: Results from the CoV-ADAPT cohort

Despite recent advances in prophylactic vaccination, SARS-CoV-2 infections continue to cause significant morbidity. A better understanding of immune response differences between vaccinated individuals with and without later SARS-CoV-2 breakthrough infection is urgently needed. CoV-ADAPT is a prospective long-term study comparing humoral (anti-spike-RBD-IgG, neutralization capacity, avidity) and cellular (spike-induced T-cell interferon-γ [IFN-γ] release) immune responses in individuals vaccinated against SARS-CoV-2 at four different time points (three before and one after third vaccination). In this cohort study, 62 fully vaccinated individuals presented with SARS-CoV-2 breakthrough infections vs 151 without infection 3-7 months following third vaccination. Breakthrough infections significantly increased anti-spike-RBD-IgG (p < 0.01), but not spike-directed T-cell IFN-γ release (TC) or antibody avidity. Despite comparable surrogate neutralization indices, the functional neutralization capacity against SARS-CoV-2-assessed via a tissue culture-based assay-was significantly higher following breakthrough vs no breakthrough infection. Anti-spike-RBD-IgG and antibody avidity decreased with age (p < 0.01) and females showed higher anti-spike-RBD-IgG (p < 0.01), and a tendency towards higher antibody avidity (p = 0.051). The association between humoral and cellular immune responses previously reported at various time points was lost in subjects after breakthrough infections (p = 0.807). Finally, a machine-learning approach based on our large immunological dataset (a total of 49 variables) from different time points was unable to predict breakthrough infections (area under the curve: 0.55). In conclusion, distinct differences in humoral vs cellular immune responses in fully vaccinated individuals with or without breakthrough infection could be demonstrated. Breakthrough infections predominantly drive the humoral response without boosting the cellular component. Breakthrough infections could not be predicted based on immunological data, which indicates a superior role of environmental factors (e.g., virus exposure) in individualized risk assessment.

Evaluation of PastoCovac plus vaccine as a booster dose on vaccinated individuals with inactivated COVID-19 vaccine

COVID-19 pandemic has been managed through global vaccination programs. However, the antibody waning in various types of vaccines came to notice. Hereby, PastoCovac Plus as a protein subunit vaccine was investigated in immunized health care workers by COVAXIN (BBV152). The booster vaccine was recommended at least three months post the second dose of COVAXIN. Sera collection was done before and after each injection. SARS-CoV-2 PCR test was done monthly to detect any asymptomatic and symptomatic vaccine breakthrough. 47.9 and 24.3% of the participants were seronegative for anti-N and anti-S antibodies three months after the second dose of COVAXIN, respectively. On average, fold-rises of 70, 93, 8 and mean-rises of 23.32, 892.4, 5.59 were recorded regarding neutralizing antibody, quantitative and semi-quantitative anti-Spike antibody, respectively. Anti-Spike and neutralizing antibodies seroconversion was seen 59.3% and 45.7%, respectively. The vaccine breakthrough assessment showed that all the isolated samples belonged to SARS-CoV-2 Delta variant. PastoCovac Plus boosting is strongly recommended in combination with inactivated vaccine platforms against SARS-CoV-2.

Immunogenicity of ChAdOx1 (Covishield) Booster Dose in Healthcare Providers: A Pre-Post Study

Background Worldwide, healthcare workers who face a higher risk of contracting coronavirus disease 2019 (COVID-19) were among the first to receive COVID-19 vaccinations. Following the initial two vaccine doses, health experts recommended a third booster shot to enhance protection against the severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) virus. However, limited information about how this booster dose affects antibody levels is available. This study assesses the immune response triggered by the ChAdOx1 (Covishield) booster dose. Methods We conducted a before and after study among 132 healthcare providers at a tertiary care hospital in India who had already received their initial COVID-19 vaccine doses and agreed to participate. A booster shot was administered nine months following their second vaccine dose per the prevalent norms. We collected blood samples to measure immunoglobulin-G (IgG) levels against the spike protein's receptor-binding domain of the SARS-CoV-2 virus. These blood samples were taken both when they received the booster shot and one month after the booster. We determined IgG levels using a chemiluminescence microparticle immunoassay. Result Among the participants, approximately 54% were females. Regarding occupation, about 36% were doctors, 30% were students, 20% were nursing officers, and the remaining 14% held grade-4 positions. The median age of the participants was 32 years. About 74% had no history of underlying health conditions. Before the booster dose, 29% of the participants tested negative for antibodies. However, all participants developed antibodies following the booster shot, and there was a significant increase in antibody levels, which was statistically meaningful with a p-value of less than 0.0001. Conclusion In conclusion, the administration of a booster dose effectively induced seroconversion and significantly increased antibody levels among healthcare providers, enhancing their immunity against COVID-19, essential in the face of a waning immune response to primary series vaccination.

Evaluation of the Effects of Coronavirus Vaccination Status on Inpatient Demographics and Clinical and Laboratory Data

Background The coronavirus disease 2019 (COVID-19) pandemic has been largely controlled by vaccines. However, a notable increase in COVID-19 infections has been observed among vaccinated individuals. The protection conferred by vaccination remains a topic of ongoing discussion and research. Our study aims to assess the impact of vaccination status on the demographics, clinical presentations, and laboratory characteristics of patients who were admitted to the hospital and subsequently hospitalized for further evaluation and treatment. Methods We examined hospitalized COVID-19 patients in terms of demographics, immunization status, clinical and laboratory findings, and outcomes over a seven-month period during which the delta variant was prevalent. Patients were categorized into three groups based on their vaccination status: unvaccinated (n=1,321, 53.3%), partially vaccinated (n=214, 8.6%), and fully vaccinated (n=944, 38.1%). Data from these patients were compared across groups. Results The study included 2,479 polymerase chain reaction (PCR)-confirmed hospitalized COVID-19 patients. The median ages (range) for the unvaccinated, partially vaccinated, and fully vaccinated patients who required hospitalization due to COVID-19 infection were 51 (18-98), 61 (21-91), and 71 (23-99), respectively (p<0.001). White blood cell count, neutrophils, monocytes, platelet count, and inflammatory markers such as erythrocyte sedimentation rate, C-reactive protein, procalcitonin, and IL-6, as well as fibrinogen and troponin T levels, were observed to be higher in the fully vaccinated patients compared to the unvaccinated and partially vaccinated patients. Clinical follow-ups showed that the intensive care unit (ICU) admission rates, length of hospital stay, and mortality rates were also higher in the fully vaccinated group compared to the other groups. Conclusion Our findings indicate that full vaccination significantly reduces hospitalization rates in younger individuals with average risk. However, patients with high-risk factors, such as advanced age and multiple comorbidities, exhibited higher hospitalization rates, increased need for intensive care, longer hospital stays, elevated inflammatory markers, and higher mortality even when fully vaccinated. It is crucial for elderly patients to receive thorough evaluations during emergency visits and to be provided with early treatment to reduce potential morbidity and mortality.

COVID-19 Infection despite Previous Vaccination in Cancer Patients and Healthcare Workers: Results from a French Prospective Multicenter Cohort (PAPESCO-19)

In a multicenter prospective cohort of cancer patients (CP; n = 840) and healthcare workers (HCWs; n = 935) vaccinated against COVID-19, we noticed the following: i/after vaccination, 4.4% of HCWs and 5.8% of CP were infected; ii/no characteristic was associated with post-vaccine COVID-19 infections among HCWs; iii/CP who developed infections were younger, more frequently women (NS), more frequently had gastrointestinal, gynecological, or breast cancer and a localized cancer stage; iv/CP vaccinated while receiving chemotherapy or targeted therapy had (NS) more breakthrough infections after vaccination than those vaccinated after these treatments; the opposite was noted with radiotherapy, immunotherapy, or hormonotherapy; v/most COVID-19 infections occurred either during the Alpha wave (11/41 HCW, 20/49 CP), early after the first vaccination campaign started, or during the Omicron wave (21/41 HCW, 20/49 CP), more than 3 months after the second dose; vi/risk of infection was not associated with values of antibody titers; vii/the outcome of these COVID-19 infections after vaccination was not severe in all cases. To conclude, around 5% of our CPs or HCWs developed a COVID-19 infection despite previous vaccination. The outcome of these infections was not severe.

Explicit modeling of antibody levels for infectious disease simulations in the context of SARS-CoV-2

Measurable levels of immunoglobulin G antibodies develop after infections with and vaccinations against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). These antibody levels are dynamic: due to waning, antibody levels will drop over time. During the COVID-19 pandemic, multiple models predicting infection dynamics were used by policymakers to support the planning of public health policies. Explicitly integrating antibody and waning effects into the models is crucial for reliable calculations of individual infection risk. However, only few approaches have been suggested that explicitly treat these effects. This paper presents a methodology that explicitly models antibody levels and the resulting protection against infection for individuals within an agent-based model. The model was developed in response to the complexity of different immunization sequences and types and is based on neutralization titer studies. This approach allows complex population studies with explicit antibody and waning effects. We demonstrate the usefulness of our model in two use cases.

Post-acute sequelae of COVID-19 and longitudinal antibody levels in a community-based cohort

BACKGROUND

Coronavirus disease 2019 (COVID-19) infection invokes variable immune responses and poses a risk of post-acute sequelae SARS-CoV-2 infection (PASC) symptoms; however, most data on natural history are derived from patients with severe infection. Further data are needed among patients with mild infection, who comprise most cases.

METHODS

The Dallas Fort-Worth (DFW) COVID-19 Prevalence Study included 21,597 community-dwelling adults (ages 18-89) who underwent COVID-19 PCR and anti-nucleocapsid antibody testing between July 2020 and March 2021. We invited participants with positive COVID-19 results (cases) and a subset with negative results (controls), matched on age, sex, race/ethnicity, and ZIP code, to complete a follow-up questionnaire for PASC symptoms and repeat anti-nucleocapsid testing, and anti-spike antibody testing between July and December 2021.

RESULTS

Of 3,917 adults invited to participate, 2260 (57.7%) completed the questionnaire- 1150 cases and 1110 controls. Persistent symptoms were reported in 21.1% of cases, with the most common being shortness of breath, fatigue, and loss of taste or smell. Among 292 cases with asymptomatic infection, >15% reported new fatigue and 8-10% reported new loss of taste/smell, myalgias, or headache. Median anti-nucleocapsid levels in cases decreased from 3.5U to 0.7U over a median follow-up of 8.6 months. Anti-spike antibody levels at 6-7 months post-vaccination in cases were similar to that of controls.

CONCLUSIONS

More than 1 in 5 patients with COVID-19 infection, including those with mild infection, reported persistent symptoms during follow-up. Both nucleocapsid and spike protein antibody levels decreased within six months following a COVID-19 infection and vaccination.

Comparable efficacy and safety of COVID-19 vaccines for patients receiving tegafur-uracil as postoperative adjuvant chemotherapy

PURPOSE

Many effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been developed, but a weaker response in individuals undergoing anticancer treatment has been reported. This study evaluates the immunogenic status and safety of SARS-CoV-2 vaccines for patients with non-small-cell lung cancer (NSCLC), receiving tegafur-uracil (UFT) as postoperative adjuvant chemotherapy.

METHODS

The subjects of this prospective study were 40 patients who underwent surgery for NSCLC and received SARS-CoV-2 vaccines postoperatively. We compared the antibody titers of SARS-CoV-2 vaccines and the adverse events between patients who received adjuvant UFT and patients who did not.

RESULTS

The mean anti-S1 IgG titers were not significantly different between the UFT and without-UFT groups (mean optimal density, 0.194 vs. 0.205; P = 0.76). Multivariate analysis identified the period after the second vaccination as an independent predictor of anti-S1 IgG titer (P = 0.049), but not the UFT status (with or without-UFT treatment; P = 0.47). The prevalence of adverse events did not differ significantly between the groups, and no severe adverse events occurred.

CONCLUSIONS

The efficacy and safety of the SARS-CoV-2 vaccines for NSCLC patients who received postoperative adjuvant UFT chemotherapy were comparable to those for NSCLC patients who did not receive postoperative adjuvant UFT chemotherapy.

CLINICAL TRIAL REGISTRATION

This study was registered with the University Hospital Medical Information Network (UMIN) in Japan (UMIN000047380).

Studying temporal titre evolution of commercial SARS-CoV-2 assays reveals significant shortcomings of using BAU standardization for comparison

BACKGROUND

Measuring specific anti-SARS-CoV-2 antibodies has become one of the main epidemiological tools to survey the ongoing SARS-CoV-2 pandemic, but also vaccination response. The WHO made available a set of well-characterized samples derived from recovered individuals to allow normalization between different quantitative anti-Spike assays to defined Binding Antibody Units (BAU).

METHODS

To assess sero-responses longitudinally, a cohort of ninety-nine SARS-CoV-2 RT-PCR positive subjects was followed up together with forty-five vaccinees without previous infection but with two vaccinations. Sero-responses were evaluated using a total of six different assays: four measuring anti-Spike proteins (converted to BAU), one measuring anti-Nucleocapsid proteins and one SARS-CoV-2 surrogate virus neutralization. Both cohorts were evaluated using the Euroimmun Anti-SARS-CoV-2-ELISA anti-S1 IgG and the Roche Elecsys Anti-SARS-CoV-2 anti-S1 assay.

RESULTS

In SARS-CoV-2-convalesce subjects, the BAU-sero-responses of Euroimmun Anti-SARS-CoV-2-ELISA anti-S1 IgG and Roche Elecsys Anti-SARS-CoV-2 anti-S1 peaked both at 47 (43-51) days, the first assay followed by a slow decay thereafter (> 208 days), while the second assay not presenting any decay within one year. Both assay values in BAUs are only equivalent a few months after infection, elsewhere correction factors up to 10 are necessary. In contrast, in infection-naive vaccinees the assays perform similarly.

CONCLUSION

The results of our study suggest that the establishment of a protective correlate or vaccination booster recommendation based on different assays, although BAU-standardised, is still challenging. At the moment the characteristics of the available assays used are not related, and the BAU-standardisation is unable to correct for that.

Atypical B cells and impaired SARS-CoV-2 neutralization following heterologous vaccination in the elderly

Suboptimal responses to a primary vaccination course have been reported in the elderly, but there is little information regarding the impact of age on responses to booster third doses. Here, we show that individuals 70 years or older (median age 73, range 70-75) who received a primary two-dose schedule with AZD1222 and booster third dose with mRNA vaccine achieve significantly lower neutralizing antibody responses against SARS-CoV-2 spike pseudotyped virus compared with those younger than 70 (median age 66, range 54-69) at 1 month post booster. Impaired neutralization potency and breadth post third dose in the elderly is associated with circulating "atypical" spike-specific B cells expressing CD11c and FCRL5. However, when considering individuals who received three doses of mRNA vaccine, we did not observe differences in neutralization or enrichment in atypical B cells. This work highlights the finding that AdV and mRNA COVID-19 vaccine formats differentially instruct the memory B cell response.

Impact of vaccine measures on the transmission dynamics of COVID-19

In many nations, efforts to prevent and control COVID-19 have been significantly impeded by the SARS-CoV-2 virus ongoing mutation. The Omicron strain, a more recent and prevalent strain, has had more significant detrimental effects in countries worldwide. To investigate the impact of the Omicron BA.2 strain on vaccine efficacy, we proposed a model with vaccination and immunological decline in this research. Then, we fitted our model based on the number of daily new instances reported by the government in Jilin and Shanghai, China. We estimated the effective reproduction number Re = 4.71 for the Jilin and Re = 3.32 for Shanghai. Additionally, we do sensitivity analysis to identify the critical factors affecting the effective reproduction number Re. It was found that vaccination rate, effectiveness rate, and declining rate had a significant effect on Re. Further, we investigate the relevant parameter thresholds that make Re lower than unity. Finally, rich numerical experiments were then carried out. We observed that even when vaccine efficiency was not high, increasing vaccination rates had a significant effect on early disease transmission, that limiting social distance was the most economical and rational measure to control the spread of disease, and that for a short period, reducing immune decline was not significant in curbing disease transmission.

COVID-19 Vaccination Effectiveness in the General Population of an Italian Province: Two Years of Follow-Up

We carried out a cohort study on the overall population of the province of Pescara, Italy, to assess the real-world effectiveness of SARS-CoV-2 vaccination against infection, severe, or lethal COVID-19, two years after the start of the vaccination campaign. We included all the resident or domiciled subjects, and extracted the official demographic, vaccination, COVID-19, hospital and co-pay exemption datasets from 1 January 2021, up to 15 February 2023. Cox proportional hazards analyses were adjusted for gender, age, diabetes, hypertension, COPD, major cardio- and cerebrovascular events, cancer, and kidney diseases. Throughout the follow-up (466 days on average), 186,676 subjects received greater than or equal to three vaccine doses (of ChAdOx1 nCoV-19, BNT162b2, mRNA-1273, NVX-CoV2373, or JNJ-78436735), 47,610 two doses, 11,452 one dose, and 44,989 none. Overall, 40.4% of subjects were infected with SARS-CoV-2. Of them, 2.74% had severe or lethal (1.30%) COVID-19. As compared to the unvaccinated, the individuals who received greater than or equal to one booster dose showed a ≥85% lower risk of severe or lethal COVID-19. A massive impact of vaccination was found among the elderly: 22.0% of the unvaccinated, infected individuals died, as opposed to less than 3% of those who received greater than or equal to three vaccine doses. No protection against infection was observed, although this finding was certainly influenced by the Italian restriction policies to control the pandemic. Importantly, during the Omicron predominance period, only the group who received at least a booster dose showed a reduced risk of COVID-19-related death.

SARS-CoV-2 mRNA Vaccine Elicits Sustained T Cell Responses Against the Omicron Variant in Adolescents

Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been acknowledged as an effective mean of preventing infection and hospitalization. However, the emergence of highly transmissible SARS-CoV-2 variants of concern (VOCs) has led to substantial increase in infections among children and adolescents. Vaccine-induced immunity and longevity have not been well defined in this population. Therefore, we aimed to analyze humoral and cellular immune responses against ancestral and SARS-CoV-2 variants after two shots of the BNT162b2 vaccine in healthy adolescents. Although vaccination induced a robust increase of spike-specific binding Abs and neutralizing Abs against the ancestral and SARS-CoV-2 variants, the neutralizing activity against the Omicron variant was significantly low. On the contrary, vaccine-induced memory CD4+ T cells exhibited substantial responses against both ancestral and Omicron spike proteins. Notably, CD4+ T cell responses against both ancestral and Omicron strains were preserved at 3 months after two shots of the BNT162b2 vaccine without waning. Polyfunctionality of vaccine-induced memory T cells was also preserved in response to Omicron spike protein. The present findings characterize the protective immunity of vaccination for adolescents in the era of continuous emergence of variants/subvariants.

High SARS-CoV-2 seroprevalence in Lagos, Nigeria with robust antibody and cellular immune responses

Background

Early evidence suggested that the impact of the COVID-19 pandemic was less severe in Africa compared to other parts of the world. However, more recent studies indicate higher SARS-CoV-2 infection and COVID-19 mortality rates on the continent than previously documented. Research is needed to better understand SARS-CoV-2 infection and immunity in Africa.

Methods

In early 2021, we studied the immune responses in healthcare workers (HCWs) at Lagos University Teaching Hospital (n = 134) and Oxford-AstraZeneca COVID-19 vaccine recipients from the general population (n = 116) across five local government areas (LGAs) in Lagos State, Nigeria. Western blots were used to simultaneously detect SARS-CoV-2 spike and nucleocapsid (N) antibodies (n = 250), and stimulation of peripheral blood mononuclear cells with N followed by an IFN-γ ELISA was used to examine T cell responses (n = 114).

Results

Antibody data demonstrated high SARS-CoV-2 seroprevalence of 72·4% (97/134) in HCWs and 60·3% (70/116) in the general population. Antibodies directed to only SARS-CoV-2 N, suggesting pre-existing coronavirus immunity, were seen in 9·7% (13/134) of HCWs and 15·5% (18/116) of the general population. T cell responses against SARS-CoV-2 N (n = 114) were robust in detecting exposure to the virus, demonstrating 87·5% sensitivity and 92·9% specificity in a subset of control samples tested. T cell responses against SARS-CoV-2 N were also observed in 83.3% of individuals with N-only antibodies, further suggesting that prior non-SARS-CoV-2 coronavirus infection may provide cellular immunity to SARS-CoV-2.

Conclusions

These results have important implications for understanding the paradoxically high SARS-CoV-2 infection with low mortality rate in Africa and supports the need to better understand the implications of SARS-CoV-2 cellular immunity.

Comparison of self-reported symptoms in COVID-19 patients who had or had not previously received COVID-19 mRNA vaccination

Although mRNA coronavirus disease 2019 (COVID-19) vaccines have been reported for high effectiveness against symptoms, it remains unclear whether post-vaccination infections are less symptomatic than infections in vaccine-naive individuals. We included patients with COVID-19 diagnosed by polymerase chain reaction tests during Japan's alpha and delta variant epidemics. COVID-19 symptoms at approximately 4 weeks were compared based on COVID-19 vaccination status. In total, 398 cases (372 symptomatic and 26 asymptomatic; 286 unvaccinated, 66 vaccinated with one dose, and 46 with two doses) were analyzed. The most common symptoms were fever (78.4%), fatigue (78.4%), cough (74.4%), loss of taste or smell (62.8%), and headache (59.8%). Post-vaccination infections were significantly less likely to be symptomatic. Possible confounder-adjusted odds ratios of two vaccine doses against fatigue, dry eyes and mouth, insomnia, fever, shortness of breath, unusual muscle pains, and loss of taste or smell were 0.18 (95% confidence interval [CI]: 0.09-0.38), 0.22 (95% CI: 0.08-0.59), 0.33 (95% CI: 0.14-0.80), 0.31 (95% CI: 0.15-0.63), 0.36 (95% CI: 0.16-0.76), 0.40 (95% CI: 0.19-0.82), and 0.44 (95% CI: 0.22-0.87), respectively. Post-vaccination infections after two mRNA COVID-19 vaccine doses show milder and fewer symptoms than infections in unvaccinated patients, highlighting the effectiveness of vaccination.

Vertical transmission and maternal passive immunity post-SARS-CoV-2

Since 2020, the highly contagious nature and various transmission routes of SARS-CoV-2 have rendered the pandemic interminable. Vertical transmission (VT) through the placenta and breast milk, which is frequent for certain virus types, is thought to exist for SARS-CoV-2 and is hypothesized by many researchers. Conversely, antibodies are produced to counteract the effect of viruses. Since newborns' immunologic system cannot produce proper antibodies, maternal antibodies are usually transferred from mother to infant/fetus to meet the need. This theory leads to the hypothesis of transmission of antibodies through the placenta and breast milk following SARS-CoV-2 infection or vaccination. This paper further discusses these hypotheses, considering consequences of fetus/infant harm versus benefit.

Humoral response after a BNT162b2 heterologous third dose of COVID-19 vaccine following two doses of BBIBP-CorV among healthcare personnel in Peru

Background

The inactivated virus vaccine, BBIBP-CorV, was principally distributed across low- and middle-income countries as primary vaccination strategy to prevent poor COVID-19 outcomes. Limited information is available regarding its effect on heterologous boosting. We aim to evaluate the immunogenicity and reactogenicity of a third booster dose of BNT162b2 following a double BBIBP-CorV regime.

Methods

We conducted a cross-sectional study among healthcare providers from several healthcare facilities of the Seguro Social de Salud del Perú - ESSALUD. We included participants two-dose BBIBP-CorV vaccinated who presented a three-dose vaccination card at least 21 days passed since the vaccinees received their third dose and were willing to provide written informed consent. Antibodies were determined using LIAISON® SARS-CoV-2 TrimericS IgG (DiaSorin Inc., Stillwater, USA). Factors potentially associated with immunogenicity, and adverse events, were considered. We used a multivariable fractional polynomial modeling approach to estimate the association between anti-SARS-CoV-2 IgG antibodies' geometric mean (GM) ratios and related predictors.

Results

We included 595 subjects receiving a third dose with a median (IQR) age of 46 [37], [54], from which 40% reported previous SARS-CoV-2 infection. The overall geometric mean (IQR) of anti-SARS-CoV-2 IgG antibodies was 8,410 (5,115 - 13,000) BAU/mL. Prior SARS-CoV-2 history and full/part-time in-person working modality were significantly associated with greater GM. Conversely, time from boosting to IgG measure was associated with lower GM levels. We found 81% of reactogenicity in the study population; younger age and being a nurse were associated with a lower incidence of adverse events.

Conclusions

Among healthcare providers, a booster dose of BNT162b2 following a full BBIBP-CorV regime provided high humoral immune protection. Thus, SARS-CoV-2 previous exposure and working in person displayed as determinants that increase anti-SARS-CoV-2 IgG antibodies.

Delayed and Attenuated Antibody Responses to Coronavirus Disease 2019 Vaccination With Poor Cross-Variant Neutralization in Solid-Organ Transplant Recipients-A Prospective Longitudinal Study

Background

Therapeutically immunosuppressed transplant recipients exhibit attenuated responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines. To elucidate the kinetics and variant cross-protection of vaccine-induced antibodies in this population, we conducted a prospective longitudinal study in heart and lung transplant recipients receiving the SARS-CoV-2 messenger RNA (mRNA) 3-dose vaccination series.

Methods

We measured longitudinal serum antibody and neutralization responses against the ancestral and major variants of SARS-CoV-2 in SARS-CoV-2-uninfected lung (n = 18) and heart (n = 17) transplant recipients, non-lung-transplanted patients with cystic fibrosis (n = 7), and healthy controls (n = 12) before, during, and after the primary mRNA vaccination series.

Results

Among healthy controls, strong anti-spike responses arose immediately following vaccination and displayed cross-neutralization against all variants. In contrast, among transplant recipients, after the first 2 vaccine doses, increases in antibody concentrations occurred gradually, and cross-neutralization was completely absent against the Omicron B.1.1.529 variant. However, most (73%) of the transplant recipients had a significant response to the third vaccine dose, reaching levels comparable to those of healthy controls, with improved but attenuated neutralization of immune evasive variants, particularly Beta, Gamma, and Omicron. Responses in non-lung-transplanted patients with cystic fibrosis paralleled those in healthy controls.

Conclusions

In this prospective, longitudinal analysis of variant-specific antibody responses, lung and heart transplant recipients display delayed and defective responses to the first 2 SARS-CoV-2 vaccine doses but significantly augmented responses to a third dose. Gaps in antibody-mediated immunity among transplant recipients are compounded by decreased neutralization against Omicron variants, leaving many patients with substantially weakened immunity against currently circulating variants.

High Levels of Anti-SARS-CoV-2 Receptor-Binding Domain (RBD) Antibodies One Year Post Booster Vaccinations among Hospital Workers in Indonesia: Was the Second Booster Needed?

In August 2022, Indonesia prioritized healthcare workers to receive the second booster dose. We conducted a sequential serosurvey to understand the dynamics of the antibody titers. The first serosurvey, which was conducted in June 2021, 1-6 months after Sinovac vaccination, showed a median antibody level of 41.4 BAU/mL (interquartile range (IQR): 10-629.4 BAU/mL). The second serosurvey was conducted one month (August 2021) after the first Moderna booster vaccine and showed a median level of 4000 BAU/mL (IQR: 3081-4000 BAU/mL). The last serosurvey was conducted a year (August 2022) after the booster and showed a median level of 4000 BAU/mL (IQR: 4000-4000 BAU/mL). In this last survey, only 39 (11.9%) of healthcare workers had antibody levels below the maximum level of 4000 BAU/mL. Thus, one year after the first booster dose, we did not observe the waning of antibody levels. The average increase was perhaps because of natural infection. Based on these considerations, we believe that a second booster dose was not necessary for this category of subjects at that time. Because vaccine supply is often limited, priority could be given to the general population or other high-risk patient groups with low antibody titers based on serological tests.

Kinetics of specific anti-SARS-CoV-2 IgM, IgA, and IgG responses during the first 12 months after SARS-CoV-2 infection: A prospective longitudinal study

Coronavirus 2019 (COVID-19) is a global health threat. The kinetics of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) need to be assessed, as the long-term duration of these immunoglobulins remains largely controversial. The aim of this study was to assess the longitudinal dynamics of anti-SARS-CoV-2 antibodies against the nucleocapsid (N) protein and the receptor-binding domain (RBD) of the spike protein up to one year in a cohort of 190 COVID-19 patients. Between March and September 2021, we enrolled patients from two regional hospitals in Casablanca, Morocco. Blood samples were collected and analyzed for antibody levels. We used the commercial Euroimmun ELISA for the determination of anti-N IgM, the Abbott Architect™ SARS-CoV-2 IgG test for the detection of anti-RBD IgG, and an in-house kit for the assay of anti-N IgG and anti-N IgA. IgM and IgA antibodies were assessed 2-5, 9-12, 17-20 and 32-37 days after symptom onset. IgG antibodies were also assessed 60, 90, 120 and 360 days after symptom onset. One-third of patients developed IgM (32%), while two-thirds developed IgA (61%). One month of symptom onset, most patients developed IgG, with 97% and 93% positivity for anti-RBD IgG and anti-N IgG, respectively. The anti-RBD IgG positivity rate remained high up to one year of follow-up. However, the anti-N IgG positivity rate decreased over time, with only 41% of patients testing positive after one year's follow-up. IgG levels were significantly higher in older people (over 50 years) than in other study participants. We also found that patients who had received two doses of ChAdOx1 nCoV-19 vaccine prior to infection had a lower IgM response than unvaccinated patients. This difference was statistically significant two weeks after the onset of symptoms. We present the first study in Africa to measure the kinetics of antibody response (IgA, IgM and IgG) to SARS-CoV-2 over one year. Most participants remained seropositive for anti-RBD IgG after one year but showed a significant decline in antibody titers.

Neutralizing antibody levels associated with injectable and aerosolized Ad5-nCoV boosters and BA.2 infection

BACKGROUND

Several COVID-19 vaccines are in widespread use in China. Few data exist on comparative immunogenicity of different COVID-19 vaccines given as booster doses. We aimed to assess neutralizing antibody levels raised by injectable and inhaled aerosolized recombinant adenovirus type 5 (Ad5)-vectored COVID-19 vaccine as a heterologous booster after an inactivated COVID-19 vaccine two-dose primary series.

METHODS

Using an open-label prospective cohort design, we recruited 136 individuals who had received inactivated vaccine primary series followed by either injectable or inhaled Ad5-vectored vaccine and measured neutralizing antibody titers against ancestral SARS-CoV-2 virus and Omicron BA.1 and BA.5 variants. We also measured neutralizing antibody levels in convalescent sera from 39 patients who recovered from Omicron BA.2 infection.

RESULTS

Six months after primary series vaccination, neutralizing immunity against ancestral SARS-CoV-2 was low and neutralizing immunity against Omicron (B.1.1.529) was lower. Boosting with Ad5-vectored vaccines induced a high immune response against ancestral SARS-CoV-2. Neutralizing responses against Omicron BA.5 were ≥ 80% lower than against ancestral SARS-CoV-2 in sera from prime-boost subjects and in convalescent sera from survivors of Omicron BA.2 infection. Inhaled aerosolized Ad5-vectored vaccine was associated with greater neutralizing titers than injectable Ad5-vectored vaccine against ancestral and Omicron SARS-CoV-2 variants.

CONCLUSIONS

These findings support the current strategy of heterologous boosting with injectable or inhaled Ad5-vectored SARS-CoV-2 vaccination of individuals primed with inactivated COVID-19 vaccine.

Safety and Immunogenicity of Homologous and Heterologous Adenoviral-Vectored and mRNA COVID-19 Vaccine Regimens in Radiotherapy Patients

Diminished immune response after vaccination occurs in cancer patients. This observational study evaluated the immune response and safety profile after COVID-19 vaccination in radiotherapy patients. The study comprised 53 cancer patients undergoing radiotherapy and voluntarily received the COVID-19 vaccine. The two regimens were homologous ChAdOx1-S recombinant (AstraZeneca, AZ), "AZ-AZ" and heterologous "AZ-mRNA". The seroconversion rate and anti-RBD immunoglobulin geometric mean titers (GMT) were assessed and compared with healthy controls. Adverse effects were assessed using a questionnaire. The seroconversion rate was 52.4% 1 month after the first dose with GMT 4.3 U/mL (95%CI 1.4-13). Following the second dose, the AZ-AZ group achieved 95% seroconversion rate with GMT = 188.4 U/mL (95%CI 67.1-529), which was significantly lower than the healthy cohort, GMT = 945 U/mL (95%CI 708-1261). Cancer patients in AZ-mRNA group achieved a 100% seroconversion rate with a high GMT = 1400.8 U/mL (95%CI 429.5-4566), which was significantly lower than the healthy cohort, GMT = 5169.9 U/mL (95%CI 3582.2-7461.5). Most adverse effects were mild. Our findings suggest that radiotherapy patients had fair immunogenicity after the first dose, but achieved a high seroconversion rate after the second dose with manageable adverse effects. However, their immunologic response was lower than in healthy individuals, indicating that other preventive strategies are needed.

Intranasal delivery of an adenovirus-vector vaccine co-expressing a modified spike protein and a genetic adjuvant confers lasting mucosal immunity against SARS-CoV-2

The ongoing COVID-19 pandemic caused by SARS-CoV-2 infection has threatened global health. Since the first case of infection was reported in December 2019, SARS-CoV-2 has rapidly spread worldwide and caused millions of deaths. As vaccination is the best way to protect the host from invading pathogens, several vaccines have been developed to prevent the infection of SARS-CoV-2, saving numerous lives thus far. However, SARS-CoV-2 constantly changes its antigens, resulting in escape from vaccine-induced protection, and the longevity of immunity induced by vaccines remains an issue. Additionally, traditional intramuscular COVID-19 vaccines are insufficient at evoking mucosal-specific immune responses. Because the respiratory tract is the primary route of SARS-CoV-2 entry, the need for mucosal vaccines is strong. Using an adenoviral (Ad) vector platform, we generated Ad5-S.Mod, a recombinant COVID-19 vaccine that encodes modified-spike (S) antigen and the genetic adjuvant human CXCL9. Intranasal delivery of Ad5-S.Mod elicited superior airway humoral and T-cell responses over traditional intramuscular vaccines and protected mice from lethal SARS-CoV-2 infection. cDC1 cells were required for the generation of antigen-specific CD8⁺ T-cell responses and CD8⁺ tissue-resident memory T-cell development in intranasal Ad5-S.Mod vaccinated mice. Furthermore, we confirmed the efficacy of the intranasal Ad5-S.Mod vaccine in terms of transcriptional changes and identified lung macrophages as a key supporter of maintenance of lung-resident memory T and B cells. Our study demonstrates Ad5-S.Mod has the potential to confer protective immunity against SARS-CoV-2 and that lung macrophages support the maintenance of vaccine-induced tissue-resident memory lymphocytes.

Impact of timing and combination of different BNT162b2 and ChAdOx1-S COVID-19 basic and booster vaccinations on humoral immunogenicity and reactogenicity in adults

In this single-center observational study with 1,206 participants, we prospectively evaluated SARS-CoV-2-antibodies (anti-S RBD) and vaccine-related adverse drug reactions (ADR) after basic and booster immunization with BNT162b2- and ChAdOx1-S-vaccines in four vaccination protocols: Homologous BNT162b2-schedule with second vaccination at either three or six weeks, homologous ChAdOx1-S-vaccination or heterologous ChAdOx1-S/BNT162b2-schedule, each at 12 weeks. All participants received a BNT162b2 booster. Blood samples for anti-S RBD analysis were obtained multiple times over a period of four weeks to six months after basic vaccination, immediately before, and up to three months after booster vaccination. After basic vaccination, the homologous ChAdOx1-S-group showed the lowest anti-S RBD levels over six months, while the heterologous BNT162b2-ChAdOx1-S-group demonstrated the highest anti-S levels, but failed to reach level of significance compared with the homologous BNT162b2-groups. Antibody levels were higher after an extended vaccination interval with BNT162b2. A BNT162b2 booster increased anti-S-levels 11- to 91-fold in all groups, with the homologous ChAdOx1-S-cohort demonstrated the highest increase in antibody levels. No severe or serious ADR were observed. The findings suggest that a heterologous vaccination schedule or prolonged vaccination interval induces robust humoral immunogenicity with good tolerability. Extending the time to boost-immunization is key to both improving antibody induction and reducing ADR rate.

Transmission and Risk Factors of COVID-19 among Health Care Workers

Coronavirus disease 2019 (COVID-19) poses a significant occupational risk factor to health care workers (HCWs). As in previous events, this occupational risk amplifies and compounds the adverse impact of the pandemic. We conducted a narrative review summarizing risk factors associated with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) transmission in HCWs. We searched for original observational studies (including case-control, cross-sectional, prospective and retrospective cohorts) using PubMed, Scopus, and Google Scholar. A total of 22 articles were reviewed, including eligible English articles published between April 2020 and May 2022. Job category, work environment, personal protective equipment (PPE) noncompliance, lack of PPE awareness and training, unvaccinated status, and competing community and household exposures were identified as risk factors for SARS-CoV-2 transmission among HCWs. Effective measures to protect HCWs from SARS-CoV-2 need to account for the identified occupational risk factors. Identifying and understanding COVID-19 risk factors among HCWs must be considered a public health priority for policy makers to mitigate occupational and community transmission in current and future epidemics.