PastoCovac and PastoCovac Plus as protein subunit COVID-19 vaccines led to great humoral immune responses in BBIP-CorV immunized individuals

Long-term assessment of anti-SARS-CoV-2 antibody levels post-pandemic: Tracking the dynamics after two, three, and four COVID-19 vaccine doses

BACKGROUND

Given the limited available data about to the number of vaccine doses administered over an extended time in Iran, the immune status of vaccinated individuals and any potential disparities in this regard among those who received different numbers of vaccine doses remain unknown. Therefore, this study aimed to assess humoral immunity of individuals who received different doses of the COVID-19 vaccines in Iran.

METHODS

This study was conducted from February, 2022 to December 2023 including 605 vaccinated subjects. The durability of anti-spike, anti-nucleocapsid (NCP), neutralizing antibody, and interferon-γ (IFN-γ) was evaluated at least 6 months after the last vaccination, as well as 60 and 120 days after it, in individuals who received two or three doses of the COVID-19 vaccine. Furthermore, the evaluation of humoral and cellular response was performed before the fourth dose (second booster) as well as 21 and 60 days thereafter.

RESULTS

The 3-dose group showed significantly higher levels of anti-spike, neutralizing antibodies, and IFN-γ compared to the 2-dose group. Both the 2-dose and 3-dose groups experienced a slight decrease in the dynamic of SARS-CoV-2 Abs, though the associated levels remained within a positive range. After receiving the fourth dose of PastoCovac, most participants had significantly high levels of anti-spike, neutralizing antibodies, and IFN-γ, regardless of the type of three-dose regimen they had previously received. The average antibody titer decreased after 60 days from the fourth dose, but remained relatively stable during the follow-up period.

CONCLUSION

This study found that the level of anti-SARS-CoV-2 antibodies and IFN-γ, as well as their durability, were still within a positive range in 2-dose and 3-dose vaccinated groups over the long-term follow-up. Furthermore, PastoCovac vaccine enhanced humoral and cellular immune responses and could be recommended as a booster dose for individuals previously vaccinated with any previously administered COVID-19 vaccine.

Improving Vaccine Response through Probiotics and Micronutrient Supplementation: Evaluating the Role of TLR5 in Adult Female BALB/c Mice

BACKGROUND

The role of probiotics and micronutrients in improving immune system function and response to vaccination has been proven. Hence, this study aimed to investigate the effects of probiotics enriched with micronutrients on the immunogenicity of PastoCovac® vaccine.

METHODS

The probiotic supplement BioBoost® and PastoCovac® vaccine, which contain six expressed Receptor- binding Domains (RBD) and conjugated with tetanus toxin, were administered concurrently. The safety and efficacy were assessed by determining Immunoglobulin G (IgG) antibody titers to RBD and cytokines, mRNA expression of Toll-like Receptors (TLRs) 5, and clinical symptoms.

RESULTS

Results revealed that the administration of the probiotics enriched with micronutrients and vitamins for 14 days before the first vaccine dose, followed by continued supplementation for 14 days after the first dose, and in conjunction with the second vaccine dose, yielded the most significant elevation in Interleukin 4 (IL-4), Tumor Necrosis Factor-alpha (TNF alpha), Interferon-gamma (IFN-gamma), and anti-SARS-CoV-2 RBD IgG levels within the supernatant samples collected from spleen cultures with the highest expression of TLR5 genes in intestinal samples, compared to the control group.

CONCLUSION

Our results indicated that the inclusion of probiotics enriched with micronutrients and vitamins significantly enhanced the immunogenicity of the PastoCovac® vaccine. Based on the recommendation to administer third and fourth vaccine doses, particularly for vulnerable and elderly individuals, the utilization of supplements containing probiotics is expected to favorably influence immune responses.

Maintenance of Long-Term Effective Humoral Immune Response in Patients with COVID-19 with Homologous or Heterologous Booster Vaccines: A Retrospective Study

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and first identified in Wuhan, China, in December 2019, has led to global efforts in vaccination to mitigate rising morbidity and mortality, with vaccines proving crucial in controlling the pandemic. This study evaluated the humoral responses to the inactivated virus vaccine Sinopharm or Koxing Kerlafor, the protein subunit vaccine ZF001, and the adenoviral vector vaccine Convidecia after 18 months of inactivated virus vaccination by heterologous and homologous booster vaccination in patients with previous SARS-CoV-2 infection and healthy individuals. We discovered that patients who had recovered from the infection and then received a third vaccine dose (booster) exhibited durable immunity. Furthermore, the heterologous booster vaccine induced higher neutralizing antibody responses compared with the homologous booster. These findings offer valuable insights into the efficacy of different COVID-19 vaccine strategies following booster immunization.

Analysis of immunological and biochemical parameters after booster dose vaccination using protein-based and inactivated virus vaccine for safety

Introduction

Heterologous vaccines enhance the immune response to new variants and allow flexibility in booster administration when the original vaccine is unavailable. Studies show that heterologous boosters can generate comparable or superior antibody responses compared to homologous boosters. Considering rare side effects is essential in evaluating COVID-19 vaccines, especially those associated with ChAdOx1-S (AstraZeneca) and Ad26.COV2.S (Janssen), including blood clotting and idiopathic thrombocytopenia. Severe side effects, such as myocarditis and pericarditis, may occur after Pfizer or Moderna boosters but are rare.

Methods

This study administered two vaccines: the Sinopharm inactivated virus vaccine and the Razi-CoV-Pars (RCP) booster. Various evaluations included biochemical markers, coagulation factors, autoimmune antibodies, and antibodies against concerning variants.

Results

All 90 participants exhibited a notable rise in antibody levels against the variant of concern (VOC). Participants receiving the Razi-CoV-Pars booster after Sinopharm/BBIBP-CorV showed significantly higher antibody levels (Wuhan ∼ 3.25 times, Delta ∼4 times, Omicron ∼ 14 times) compared to those receiving Sinopharm's homologous vaccine. No significant changes (P: <0.05) were found in LDH, CPK, CK-MB, ANA, and Anti-CCP levels. However, individuals receiving Sinopharm's booster after two doses showed a significant increase (4 cases) in D-Dimer levels.

Conclusion

The Razi-CoV-Pars vaccine demonstrates a favorable safety profile and promising potential as an effective booster against current variants, particularly due to its significant protective titer against Omicron.

Comparative assessment of a COVID-19 vaccine after technology transfer to Iran from critical quality attributes to clinical and immunogenicity aspects

During COVID-19 pandemic, international pharmaceutical companies put effort to build global manufacturing networks for vaccines. Soberana Plus vaccine, a recombinant protein based vaccine (RBD dimer), with the trade name of PastoCovac Plus in Iran, is based on a protein subunit platform in Cuba and completed preclinical and toxicological assessments. This study aimed at presenting the steps of vaccine technology transfer from Cuba to Iran. This study provides the first practical comparability results in Iran to ensure the quality, safety and efficacy of a protein subunit vaccine against COVID-19 after a successful technology transfer from Cuba. PastoCovac Plus was transferred to Iran at the formulation stage. The assessment of the active ingredient pharmaceutical (API) was achieved through physicochemical and clinical data collection and tests to assure if there was any adverse impact on the vaccination results. In order to assess the quality of the vaccine product after technology transfer, we sought different properties including regulatory features, physicochemical quality, vaccine potency and stability as well as its immunogenicity and safety. Following the evaluation of the clinical quality attributes (CQAs) based on the standard protocols, the results showed that the two vaccines are highly similar and comparable, with no considerable effect on safety or efficacy profiles. The CQAs were all in the acceptance limits in terms of safety and efficacy as well as clinical evaluation results. The immunogenicity evaluation also confirmed no significant differences between the vaccines regarding reinfection (P = 0.199) or vaccine breakthrough (P = 0.176). Furthermore, the level of anti-spike and neutralizing antibodies in the both vaccine groups was not significantly different indicating the equality of performance between the two vaccines. According to the results of the quality and clinical assessment of this study, we achieved an acceptable quality attributes and acceptant limits in terms of safety and efficacy of the vaccines pre and post technology transfer.

COVID-19 Vaccination Adverse Events in Children: An Investigation with a Control Group in Tabriz Metropolitan City

The occurrence of adverse events following vaccination with the novel coronavirus disease 2019 (COVID-19) vaccine in children remains somewhat unclear, with only a limited number of population-based studies having been conducted in this age group. The objective of this study is to ascertain the short-term adverse events associated with the Sinopharm and Soberana (Pasto CoVac) vaccination in children between the ages of 5 and 12. This study employs an observational design with a control group. The cluster sampling method was employed to recruit the study samples, with healthcare centers and mass vaccination centers of Tabriz designated as clusters. The ratio of the vaccinated and unvaccinated groups was 2:1, respectively. Information was gathered via telephone interviews with the parents or guardians of the subjects. The data were analyzed using a mixed-effect logistic regression model. In this study, a total of 913 children were investigated, comprising 577 vaccinated and 336 unvaccinated children. The results demonstrated that the most frequent complication among the vaccinated children was injection site pain, occurring in 178 cases (30.8%, 95% CI:( 27%, 35%)) The most frequently reported systemic adverse events among vaccinated and unvaccinated children were fever (9.0% vs. 3.6%, p = 0.003), fatigue (5.5% vs. 0.9%, p = 0.002), and headache (2.9% vs. 0.6%, p = 0.032). No serious adverse events, including myocarditis, multisystem inflammatory syndrome (MIS), or hospitalization, were reported. The odds of experiencing any symptoms in the vaccinated group, adjusted for potential confounding variables, were significantly higher than in the control group (adjusted OR = 4.71, CI 95%: (3.04, 7.26), with a p-value of less than 0.001. The results indicate that the Sinopharm and Soberana (PastoCoVac) vaccines did not have any serious adverse effects. Moreover, it appears that some of the reported adverse events in other studies may be overestimated due to the absence of a control group.

Assessment of COVID-19 Vaccine Impact on Women's Menstrual Health within an 18-Month Follow-Up

Considering menstruation as a crucial factor in females' health and fertility, any factor that could change its cycle is important. This study was conducted from April 2021 to October 2022 on females who got 3 doses of vaccines against SARS-CoV-2 through different platforms. The participants were requested to provide the trained experts with any changes regarding menstrual cycles after each dose of the vaccine up to 6 months after the booster shots. The disturbances related to the vaccines were identified by the adverse events committee to find possible associations with the applied vaccines. Of 308 women who participated until the end of the study, 22 (7.1%) complained about at least one abnormality in their menstrual patterns. The most common disturbance was metrorrhagia as 10 (48%) incidences followed by menorrhagia as 6 events (24.2%). Notably, the identified complaints were persistent in 59% of the patients. In addition, 14 studied cases developed COVID-19 infection after menstrual disorders. In these cases, COVID-19 could also play a role in the persistence of postvaccine menstrual disturbances. COVID-19 vaccination could affect menstrual cycle in women with no remarkable previous medical history. More longitudinal studies are required regarding this issue.

Comparison of Adverse Events and Antibody Responses Among Different COVID-19 Vaccination Schedules

Global investment in developing COVID-19 vaccines has been substantial, but vaccine hesitancy has emerged due to misinformation. Concerns about adverse events, vaccine shortages, dosing confusion, mixing vaccines, and access issues contribute to hesitancy. Initially, the WHO recommended homologous vaccination (same vaccine for both doses), but evolving factors led to consideration of heterologous vaccination (different vaccines). The study compared reactogenicity and antibody response for both viral protein spike (S) and nucleocapsid (N) in 205 participants who received three vaccination regimens: same vaccine for all doses (Pfizer), two initial doses of the same vaccine (CoronaVac or AstraZeneca), and a Pfizer booster. ChAdOx1 and BNT162b2 vaccines were the most reactogenic vaccines, while CoronaVac vaccine was the least. ChAdOx1 and BNT162b2 achieved 100% of S-IgG seropositivity with one dose, while CoronaVac required two doses, emphasizing the importance of the second dose in achieving complete immunization across the population with different vaccine regimes. Pfizer recipients showed the highest S-IgG antibody titers, followed by AstraZeneca recipients, both after the first and second doses. A third vaccine dose was essential to boost the S-IgG antibodies and equalize the antibody levels among the different vaccine schedules. CoronaVac induced N-IgG antibodies, while in the Pfizer and AstraZeneca groups, they were induced by a natural infection, reinforcing the role of N protein as a biomarker of infection.

COVID-19: Post infection implications in different age groups, mechanism, diagnosis, effective prevention, treatment, and recommendations

SARS-CoV-2 is a highly contagious pathogen that predominantly caused the COVID-19 pandemic. The persistent effects of COVID-19 are defined as an inflammatory or host response to the virus that begins four weeks after initial infection and persists for an undetermined length of time. Chronic effects are more harmful than acute ones thus, this review explored the long-term effects of the virus on various human organs, including the pulmonary, cardiovascular, and neurological, reproductive, gastrointestinal, musculoskeletal, endocrine, and lymphoid systems and found that SARS-CoV-2 adversely affects these organs of older adults. Regarding diagnosis, the RT-PCR is a gold standard method of diagnosing COVID-19; however, it requires specialized equipment and personnel for performing assays and a long time for results production. Therefore, to overcome these limitations, artificial intelligence employed in imaging and microfluidics technologies is the most promising in diagnosing COVID-19. Pharmacological and non-pharmacological strategies are the most effective treatment for reducing the persistent impacts of COVID-19 by providing immunity to post-COVID-19 patients by reducing cytokine release syndrome, improving the T cell response, and increasing the circulation of activated natural killer and CD8 T cells in blood and tissues, which ultimately reduces fever, nausea, fatigue, and muscle weakness and pain. Vaccines such as inactivated viral, live attenuated viral, protein subunit, viral vectored, mRNA, DNA, or nanoparticle vaccines significantly reduce the adverse long-term virus effects in post-COVID-19 patients; however, no vaccine was reported to provide lifetime protection against COVID-19; consequently, protective measures such as physical separation, mask use, and hand cleansing are promising strategies. This review provides a comprehensive knowledge of the persistent effects of COVID-19 on people of varying ages, as well as diagnosis, treatment, vaccination, and future preventative measures against the spread of SARS-CoV-2.

Iran's research prioritization: Are we meeting the goals? A study based on clinical trial registry data

The prioritization of research topics in the health domain is a critical step toward channelling efforts and resources into areas that have received less attention. The objective of this study is to evaluate the implementation of research priorities determined at the national level within Iran for the period spanning five years between 2009 and 2013. We extracted the required data from the Iranian Registry of Clinical Trials (IRCT) website. Then we conducted a matching process between the titles of trials registered in the IRCT until December 3rd, 2013, and the list of national health research priorities in the domains of communicable and non-communicable diseases. The latter was compiled and regulated by the Research and Technology Deputy of the Ministry of Health since 2008. Out of the total 5,049 clinical trials registered in IRCT, 92.3% were carried out within the domain of non-communicable diseases, while 6.1% pertained to the field of communicable diseases and the remaining 1.3% in other fields. 56.4% of the clinical trials conducted in the field of communicable diseases and 32.8% of those conducted in the field of non-communicable diseases were consistent with the research priorities determined in these two fields. During the five-year period of the prioritization goal, there was no significant improvement in adherence to the list of priorities compared to the previous five-year period. Furthermore, certain priorities were neglected within both areas during these periods. It is possible to evaluate the effectiveness of research prioritization using the data obtained from the registration centers of clinical trials. Our study has revealed that the list of priorities has not garnered adequate attention from the research community within the country. Hence, remedial measures are imperative to ensure the priorities are given more attention after publication.

Long-term rheumatoid manifestations as a consequence of COVID-19 and/or vaccination: A case report after a 2-year follow-up

COVID-19 is now established as a multi-organ involvement disease with a broad range of manifestations. Identification of post-acute COVID-19 incidence is critical according to increasing number of late symptoms reports. Hereby, we report a case with a past history of COVID-19 who presented different manifestations including osteoarticular and neurological involvement within a long-term follow-up. The organs involvement initiated lately after primary vaccinations (with inactivated vaccine) and lasted few months without any pre-existing medical condition. However, upon the completion of the vaccine schedule and receiving a protein subunit vaccine, PastoCovac Plus, as a booster, the symptoms improved substantially and resolved, though in the reinfection episode partial, reoccurrence was recorded. This presentation can be a challenging issue owing to the fact that the majority of global population are vaccinated and also experience COVID-19 in this era and sometimes differentiation between consequences of the virus as post COVID-19 or the vaccination side effects is difficult.

The impact of ABO blood types on humoral immunity responses and antibody persistency after different COVID-19 vaccine regimens

This study evaluated the possible effects of blood types on coronavirus disease (COVID-19) vaccine immunogenicity and antibody (Ab) persistency. Five different vaccinated groups against COVID-19 were investigated at Pasteur Institute of Iran from April 2021 to December 2022. Anti-Spike IgG and neutralizing Ab rise were tracked on Day 21 as well as the humoral immune persistency assessment 180 after booster shots. Late adverse events up to 6 months after the booster dose were collected. The results showed that blood type A, led to a significantly higher anti-Spike Ab rise in AstraZeneca primed recipients in comparison with Sinopharm primed ones in heterologous regimens (p: 0.019). Furthermore, blood type O was a great co-effector in homologous AstraZeneca recipients regarding neutralizing Ab rise (0.013). In addition, blood type O led to a better anti-Spike Ab persistency in the Sinopharm homologous group whereas type A had the best effect on neutralizing Ab durability in the same vaccine group. What is more, Rh-positive individuals in AstraZeneca + PastoCovac Plus group had a higher rate of anti-Spike Ab rise (p = 0.001). Neutralizing Ab rise was also induced in AstraZeneca homologous and heterologous regimens of Rh-positive individuals significantly higher than Sinopharm primed cases. The present study showed the potential impact of blood types A/O and Rh-positive on a better humoral immune responses and Ab persistency. It is proposed that blood type A and Rh-positive could increase the Ab rise in AstraZeneca vaccinated individuals. Moreover, blood type O might be a better co-effector of anti-Spike Ab persistency in Sinopharm recipients.

Detection of CTLA-4 level and humeral immune response after the second dose of COVID-19 vaccine in certain Iraqi provinces participants

BACKGROUND

Evaluating immune responses following COVID-19 vaccination is paramount to understanding vaccine effectiveness and optimizing public health interventions. This study seeks to elucidate individuals' immune status after administering a second dose of diverse COVID-19 vaccines. By analyzing immune responses through serological markers, we aim to contribute valuable insights into the uniformity of vaccine performance.

METHODS

A total of 80 participants were enrolled in this study, with demographic and COVID-19 infection-related data collected for categorization. Serum samples were acquired within a specified timeframe, and SARS-CoV-2 IgM/IgG rapid tests were conducted. Moreover, CTLA-4 levels were measured through ELISA assays, allowing us to assess the immune responses comprehensively. The participants were divided into eight groups based on various factors, facilitating a multifaceted analysis.

RESULTS

The outcomes of our investigation demonstrated consistent immune responses across the diverse types of COVID-19 vaccines administered in Iraq. Statistical analysis revealed no significant distinctions among the vaccine categories. In contrast, significant differences were observed in CTLA-4 among the control group (non-infected/non-vaccinated, infected/non-vaccinated) and infected/Pfizer, non-infected/Pfizer, and infected/Sinopharm, non-infected/sinopharm (P = 0.001, < 0.001, 0.023, respectively). This suggests that these vaccines exhibit comparable effectiveness in eliciting an immune response among the study participants.

CONCLUSIONS

In conclusion, our study's results underscore the lack of discriminatory variations between different COVID-19 vaccine types utilized in Iraq. The uniform immune responses observed signify the equitable efficacy and performance of these vaccines. Despite minor quantitative discrepancies, these variations do not hold statistical significance, reaffirming the notion that the various vaccines serve a similar purpose in conferring protection against COVID-19.

Lessons from COVID-19 Pandemic: A Successful Policy and Practice by Pasteur Institute of Iran

The present study aims to provide an insight to the comprehensive efforts of Pasteur Institute of Iran (PII) regarding COVID-19 management, research, achievements, and vaccine production, though there are many challenges. The relevant literature review was investigated through national and international database and also reports from the related research departments. Six strategies were taken by PII to manage the pandemic of COVID-19. While this pandemic has been hopefully controlled, SARS-CoV-2 could still be a potential threat. Therefore, COVID-19 data management and updated studies, as well as long-term safety and efficacy of the SARS-CoV-2 vaccines are still on the agenda.

Determination of COVID-19 Late Disorders as Possible Long-COVID and/or Vaccination Consequences

In this era in which the vast majority of the global population have developed COVID-19 infection and/or got vaccinated against it, identification of the late disorders as the vaccines' side effect or long-COVID manifestation seems essential. This study included the vaccinated individuals of 4 different vaccine regimens including inactivated virus-based, subunit protein, and adenovirus-based vaccines in a follow-up schedule 6-month post the booster shot. All the documented vaccine adverse events were thoroughly assessed considering the cases' medical history by Adverse Events Committee of Pasteur Institute of Iran. Totally 329 individuals who got 3 doses of vaccination were followed 6 months after the booster shots among whom 41 (12.4%) cases with the mean age of 40.9 ± 10.48 years had a type of disorder. Gynecological and osteoarticular involvements were the most common recorded disorders of which 73.1% were possibly linked to vaccination outcomes and the rest were affected by both long-COVID-19 and vaccination. Notably, the average time of symptoms persistence was 155 ± 10.4 days. This study has the advantage of long-term follow-up which presents various forms of late events in each episode of COVID-19 infection and vaccination. About 26.8% of people with persistent complications suffered from both long-COVOD/ vaccination in whom the differentiation between the vaccine side effect and long-COVID manifestation was quite challenging. Long-term follow-up studies in large population seems essential to outline the role of long-COVID and vaccination regarding persistent complications.

Convalescent Adaptive Immunity Is Highly Heterogenous after SARS-CoV-2 Infection

The optimal detection strategies for effective convalescent immunity after SARS-CoV-2 infection and vaccination remain unclear. The objective of this study was to characterize convalescent immunity targeting the SARS-CoV-2 spike protein using a multiparametric approach. At the beginning of the pandemic, we recruited 30 unvaccinated convalescent donors who had previously been infected with COVID-19 and 7 unexposed asymptomatic controls. Peripheral blood mononuclear cells (PBMCs) were obtained from leukapheresis cones. The humoral immune response was assessed by measuring serum anti-SARS-CoV-2 spike S1 subunit IgG via semiquantitative ELISA, and T-cell immunity against S1 and S2 subunits were studied via IFN-γ enzyme-linked immunosorbent spot (ELISpot) and flow cytometric (FC) activation-induced marker (AIM) assays and the assessment of cytotoxic CD8+ T-cell function (in the subset of HLA-A2-positive patients). No single immunoassay was sufficient in identifying anti-spike convalescent immunity among all patients. There was no consistent correlation between adaptive humoral and cellular anti-spike responses. Our data indicate that the magnitude of anti-spike convalescent humoral and cellular immunity is highly heterogeneous and highlights the need for using multiple assays to comprehensively measure SARS-CoV-2 convalescent immunity. These observations might have implications for COVID-19 surveillance, and the determination of optimal vaccination strategies for emerging variants. Further studies are needed to determine the optimal assessment of adaptive humoral and cellular immunity following SARS-CoV-2 infection, especially in the context of emerging variants and unclear vaccination schedules.

Immunogenicity and safety of heterologous boost immunization with PastoCovac Plus against COVID-19 in ChAdOx1-S or BBIBP-CorV primed individuals

BACKGROUND

This study aimed at evaluation and comparison of PastoCovac Plus protein-subunit vaccine in parallel with ChAdOx1-S (AstraZeneca) and BBIBP-CorV (Sinopharm) in primarily vaccinated volunteers with two doses of ChAdOx1-S or BBIBP-CorV.

MATERIALS AND METHODS

194 volunteers enrolled the study who were previously primed with 2 doses of ChAdOx1-S or BBIBP-CorV vaccines. They were divided into two heterologous regimens receiving a third dose of PastoCovac Plus, and two parallel homologous groups receiving the third dose of BBIBP-CorV or ChAdOx1-S. Serum samples were obtained just before and 4 weeks after booster dose. Anti-spike IgG and neutralizing antibodies were quantified and the conventional live-virus neutralization titer, (cVNT50) assay was done against Omicron BA.5 variant. Moreover, the adverse events data were recorded after receiving booster doses.

RESULTS

ChAdOx1-S/PastoCovac Plus group reached 73.0 units increase in anti-Spike IgG rise compared to the ChAdOx1-S/ ChAdOx1-S (P: 0.016). No significant difference was observed between the two groups regarding neutralizing antibody rise (P: 0.256), indicating equivalency of both booster types. Adjusting for baseline titers, the BBIBP-CorV/PastoCovac Plus group showed 135.2 units increase (P<0.0001) in anti-Spike IgG, and 3.1 (P: 0.008) unit increase in mean rise of neutralizing antibodies compared to the homologous group. Adjustment for COVID-19 history, age, underlying diseases, and baseline antibody titers increased the odds of anti-Spike IgG fourfold rise both in the ChAdOx1-S (OR: 1.9; P: 0.199) and BBIBP CorV (OR: 37.3; P< 0.0001) heterologous groups compared to their corresponding homologous arms. The odds of neutralizing antibody fourfold rise, after adjustment for the same variables, was 2.4 (P: 0.610) for the ChAdOx1-S heterologous group and 5.4 (P: 0.286) for the BBIBP CorV heterologous groups compared to their corresponding homologous groups. All the booster types had the potency to neutralize BA.5 variant with no significant difference. The highest rate of adverse event incidence was recorded for ChAdOx1-S homologous group.

CONCLUSIONS

PastoCovac Plus booster application in primed individuals with BBIBP-CorV or ChAdOx1-S successfully increased specific antibodies' levels without any serious adverse events. This vaccine could be administrated in the heterologous regimen to effectively boost humoral immune responses.

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.

A Comparative Study of Immunogenicity, Antibody Persistence, and Safety of Three Different COVID-19 Boosters between Individuals with Comorbidities and the Normal Population

Data on immunogenicity, immune response persistency, and safety of COVID-19 boosters in patients with comorbidities are limited. Therefore, we aimed to evaluate three different boosters' immunogenicity and safety in individuals with at least one underlying disease (UD) (obesity, hypertension, and diabetes mellitus) with healthy ones (HC) who were primed with two doses of the BBIBP-CorV vaccine and received a booster shot of the same priming vaccine or protein subunit vaccines, PastoCovac Plus or PastoCovac. One hundred and forty subjects including sixty-three ones with a comorbidity and seventy-seven healthy ones were enrolled. The presence of SARS-CoV-2 antibodies was assessed before the booster injection and 28, 60, 90, and 180 days after it. Moreover, the adverse events (AEs) were recorded on days 7 and 21 postbooster shot for evaluating safety outcomes. Significantly increased titers of antispike, antiRBD, and neutralizing antibodies were observed in both UD and HC groups 28 days after the booster dose. Nevertheless, the titer of antispike IgG and anti-RBD IgG was lower in the UD group compared to the HC group. The long-term assessment regarding persistence of humoral immune responses showed that the induced antibodies were detectable up to 180 days postbooster shots though with a declined titer in both groups with no significant differences (p > 0.05). Furthermore, no significant difference in antibody levels was observed between each UD subgroup and the HC group, except for neutralizing antibodies in the hypertension subgroup. PastoCovac Plus and PastoCovac boosters induced a higher fold rise in antibodies in UD individuals than BBIBP-CorV booster recipients. No serious AEs after the booster injection were recorded. The overall incidence of AEs after the booster injection was higher in the UD group than the HC group among whom the highest systemic rate of AEs was seen in the BBIBP-CorV booster recipients. In conclusion, administration of COVID-19 boosters could similarly induce robust and persistent humoral immune responses in individuals with or without UD primarily vaccinated with two doses of the BBIBP-CorV. Protein-based boosters with higher a higher fold rise in antibodies and lower AEs in individuals with comorbidities might be considered a better choice for these individuals.