Duration of SARS-CoV-2 sero-positivity in a large longitudinal sero-surveillance cohort: the COVID-19 Community Research Partnership

Ndungu F. Kinetics of naturally induced binding and neutralising anti-SARS-CoV-2 antibody levels and potencies among SARS-CoV-2 infected Kenyans with diverse grades of COVID-19 severity: an observational study

Background

Given the low levels of coronavirus disease 2019 (COVID-19) vaccine coverage in sub-Saharan Africa (sSA), despite high levels of natural severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) exposures, strategies for extending the breadth and longevity of naturally acquired immunity are warranted. Designing such strategies will require a good understanding of naturally acquired immunity.

Methods

We measured whole-spike immunoglobulin G (IgG) and spike-receptor binding domain (RBD) total immunoglobulins (Igs) on 585 plasma samples collected longitudinally over five successive time points within six months of COVID-19 diagnosis in 309 COVID-19 patients. We measured antibody-neutralising potency against the wild-type (Wuhan) SARS-CoV-2 pseudovirus in a subset of 51 patients over three successive time points. Binding and neutralising antibody levels and potencies were then tested for correlations with COVID-19 severities.

Results

Rates of seroconversion increased from day 0 (day of PCR testing) to day 180 (six months) (63.6% to 100 %) and (69.3 % to 97%) for anti-spike-IgG and anti-spike-RBD binding Igs, respectively. Levels of these binding antibodies peaked at day 28 (p<0.01) and were subsequently maintained for six months without significant decay (p>0.99). Similarly, antibody-neutralising potencies peaked at day 28 (p<0.01) but declined by three-fold, six months after COVID-19 diagnosis (p<0.01). Binding antibody levels were highly correlated with neutralising antibody potencies at all the time points analysed (r>0.60, p<0.01). Levels and potencies of binding and neutralising antibodies increased with disease severity.

Conclusions

Most COVID-19 patients generated SARS-CoV-2 specific binding antibodies that remained stable in the first six months of infection. However, the respective neutralising antibodies decayed three-fold by month-six of COVID-19 diagnosis suggesting that they are short-lived, consistent with what has been observed elsewhere in the world. Thus, regular vaccination boosters are required to sustain the high levels of anti-SARS-CoV-2 naturally acquired neutralising antibody potencies in our population.

COVID-19 seroprevalence cohort survey among health care workers and their household members in Kinshasa, DR Congo, 2020-2022

INTRODUCTION

Serological surveys offer the most direct measurement to define the immunity status for numerous infectious diseases, such as COVID-19, and can provide valuable insights into understanding transmission patterns. This study describes seroprevalence changes over time in the context of the Democratic Republic of Congo, where COVID-19 case presentation was apparently largely oligo- or asymptomatic, and vaccination coverage remained extremely low.

METHODS

A cohort of 635 health care workers (HCW) from 5 health zones of Kinshasa and 670 of their household members was interviewed and sampled in 6 rounds between July 2020 and January 2022. At each round, information on risk exposure and a blood sample were collected. Serology was defined as positive when binding antibodies against SARS-CoV-2 spike and nucleocapsid proteins were simultaneously present.

RESULTS

The SARS-CoV-2 antibody seroprevalence was high at baseline, 17.3% (95% CI 14.4-20.6) and 7.8% (95% CI 5.5-10.8) for HCW and household members, respectively, and fluctuated over time, between 9% and 62.1%. Seropositivity was heterogeneously distributed over the health zones (p < 0.001), ranging from 12.5% (95% CI 6.6-20.8) in N'djili to 33.7% (95% CI 24.6-43.8) in Bandalungwa at baseline for HCW. Seropositivity was associated with increasing rounds adjusted Odds Ratio (aOR) 1.75 (95% CI 1.66-1.85), with increasing age aOR 1.11 (95% CI 1.02-1.20), being a female aOR 1.35 (95% CI 1.10-1.66) and being a HCW aOR 2.38 (95% CI 1.80-3.14). There was no evidence that HCW brought the COVID-19 infection back home, with an aOR of 0.64 (95% CI 0.46-0.91) of seropositivity risk among household members in subsequent surveys. There was seroreversion and seroconversion over time, and HCW had a lower risk of seroreverting than household members (aOR 0.60 (95% CI 0.42-0.86)).

CONCLUSION

SARS-CoV-2 IgG antibody levels were high and dynamic over time in this African setting with low clinical case rates. The absence of association with health profession or general risk behaviors and with HCW positivity in subsequent rounds in HH members, shows the importance of the time-dependent, and not work-related, force of infection. Cohort seroprevalence estimates in a 'new disease' epidemic seem insufficient to guide policy makers for defining control strategies.

SARS-CoV-2 antibody prevalence by industry, workplace characteristics, and workplace infection prevention and control measures, North Carolina, 2021 to 2022

Background

The COVID-19 pandemic has disproportionately affected workers in certain industries and occupations, and the workplace can be a high risk setting for SARS-CoV-2 transmission. In this study, we measured SARS-CoV-2 antibody prevalence and identified work-related risk factors in a population primarily working at industrial livestock operations.

Methods

We used a multiplex salivary SARS-CoV-2 IgG antibody assay to determine infection-induced antibody prevalence among 236 adult (≥18 years) North Carolina residents between February 2021 and August 2022. We used the National Institute for Occupational Safety and Health Industry and Occupation Computerized Coding System (NIOCCS) to classify employed participants' industry and compared infection-induced IgG prevalence by participant industry and with the North Carolina general population. We also combined antibody results with reported SARS-CoV-2 molecular test positivity and vaccination history to identify evidence of prior infection. We used logistic regression to estimate odds ratios of prior infection by potential work-related risk factors, adjusting for industry and date.

Results

Most participants (55%) were infection-induced IgG positive, including 71% of animal slaughtering and processing industry workers, which is 1.5 to 4.3 times higher compared to the North Carolina general population, as well as higher than molecularly-confirmed cases and the only other serology study we identified of animal slaughtering and processing workers. Considering questionnaire results in addition to antibodies, the proportion of participants with evidence of prior infection increased slightly, to 61%, including 75% of animal slaughtering and processing workers. Participants with more than 1000 compared to 10 or fewer coworkers at their jobsite had higher odds of prior infection (adjusted odds ratio [aOR] 4.5, 95% confidence interval [CI] 1.0 to 21.0).

Conclusions

This study contributes evidence of the severe and disproportionate impacts of COVID-19 on animal processing and essential workers and workers in large congregate settings. We also demonstrate the utility of combining non-invasive biomarker and questionnaire data for the study of workplace exposures.

Association of social vulnerability index and masking adherence among children enrolled in COVID-19 community research partnership study

BACKGROUND

Individuals with high social vulnerability index (SVI) have poorer outcomes with COVID-19. Masking reduces transmission of COVID-19 among children, but how SVI plays a role in masking behavior is unknown. We aimed to measure the association of SVI with masking adherence among children during the COVID-19 pandemic.

METHODS

We conducted a multi-site, prospective syndromic surveillance study among children aged 2 - 17 years in the Southeastern United States by daily electronic surveys which solicited symptoms of COVID-19-like illness, infection with or exposure to SARS-CoV-2, masking habits, and any receipt of COVID-19 vaccines. Parents/guardians submitted surveys for their children; adolescents 13 years and older could opt to submit their own surveys. Multivariable and univariate linear models were used to measure the associations of different predictors such as SVI with masking adherence.

RESULTS

One thousand four hundred sixty-one children from 6 states and 55 counties predominately from North and South Carolina were included in the analysis. Most children in the cohort were 5 - 11 years old, non-Hispanic White, from urban counties, and with low-moderate SVI. Overall masking adherence decreased over time, and older children had higher masking adherence throughout the study period compared with younger children. Children who resided in urban counties had greater masking adherence throughout the study period than those who resided in suburban or rural counties. Masking adherence was higher among children with both low and medium SVI than those with high SVI.

CONCLUSIONS

Despite being at risk for more severe outcomes with COVID-19, children with high SVI had lower levels of masking adherence compared to those with low SVI. Our findings highlight opportunities for improved and targeted messaging in these vulnerable communities.

A stronger antibody response in increased disease severity of SARS-CoV-2

BACKGROUND

An assessment of the factors that interfere with serum levels and the persistence of anti-SARs-CoV-2 IgG antibodies is essential in order to estimate the risk of reinfection and to plan vaccination. We analyzed the impact of the severity of coronavirus disease 2019 (COVID-19) and the clinical and biological factors regarding the persistence of SARs-CoV-2 anti-spike protein (IgG-S) antibodies at 12 months.

METHODS

This was an observational, longitudinal study with individuals who had recovered from COVID-19 between August 2020 and June 2021. Peripheral blood samples were collected from volunteers who were hospitalized (SERIOUS COVID-19) and those who required no hospitalization (COVID-19 LIGHT). Samples were grouped according to days after symptom onset: up to 90, between 91 and 180, ≥ 180 days after symptom onset. A semiquantitative test for IgG anti-spike protein S1(IgG-S1) was used.

RESULTS

We analyzed 238 individuals who had recovered from COVID-19, of whom 87 had been hospitalized and 151 had not. They provided 148 and 220 samples, respectively. Among those hospitalized, males (65.5%), volunteers aged over 60 years (41.1%), comorbidities such as arterial hypertension (67.8%) and diabetes mellitus (37.9%) were most frequent. We observed higher median serum IgG-S1 titers among those who had recovered from COVID-19 and had been hospitalized, at all collection time intervals (p < 0.001). We observed a weak correlation of increasing age with humoral IgG-S1 response (Spearman correlation = 0.298). There was a greater probability of IgG-S1 antibody persistence over time among samples from hospitalized individuals compared to samples from non-hospitalized participants (p = 0.001).

CONCLUSION

This study has revealed higher titers and a higher probability of the persistence of IgG-S1 in severe cases after SARs-CoV-2 primary infection in unvaccinated recovered patients. Thus, in this study, the severe clinical presentation of COVID-19 was the main factor influencing serum levels and the persistence of IgG-S1 antibodies in COVID-19.

Broadly Reactive SARS-CoV-2-Specific T-Cell Response and Participation of Memory B and T Cells in Patients with Omicron COVID-19 Infection

January 2022 onward, India witnessed a sudden increase in Omicron COVID-19 infections, having a mild course that prompted us to identify the key host factors/immune molecules modulating disease course/outcomes. The current study evaluated the percentages of lymphocyte subsets by flowcytometry, SARS-CoV-2 specific T-cell immune response by ELISPOT, estimation of plasma cytokine/chemokine levels on a Bio-plex Multiplex Immunoassay System and anti-SARS-CoV-2 IgG levels by enzyme-linked immunosorbent assay in 19 mild Omicron infected patients, 45 mild SARS-CoV-2 (2020) patients and 36 uninfected controls from India. Natural killer cells, B and memory B cells were high in vaccinated and total Omicron-infected patients groups compared to the mild SARS-CoV-2 (2020) patient group, while CD8+ T cells were high in total Omicron-infected patients group compared to the uninfected control group (p < 0.05 each). Omicron-infected patients had T-cell response against SARS-CoV-2 whole virus, S1 proteins (wild type and delta variant) in 10 out of 17 (59%), 10 out of 17 (59%), and 8 out of 17 (47%), respectively. The current study of Omicron-infected patients elucidates broadly reactive antibody, T-cell response, and participation of memory B and T cells induced by vaccination/natural infection. The limited effect of Omicron's mutations on T-cell response is suggestive of protection from severity. Pro-inflammatory IL-6, IFN-γ, chemokines CCL-2, CCL-3, CCL-4, CCL-5, and IL-8 as potential biomarkers of Omicron infection may have future diagnostic importance. The cellular immune response data in Omicron-infected patients with parental Omicron lineage could serve as a starting point to define the readouts of protective immunity against circulating Omicron subvariants.

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.

Analysis of fatality impact and seroprevalence surveys in a community sustaining a SARS-CoV-2 superspreading event

There is an ongoing debate on the COVID-19 infection fatality rate (IFR) and the impact of COVID-19 on overall population mortality. Here, we addressed these issues in a community in Germany with a major superspreader event analyzing deaths over time and auditing death certificates in the community.18 deaths that occurred within the first six months of the pandemic had a positive test for SARS-CoV-2. Six out of 18 deaths had non-COVID-19 related causes of death (COD). Individuals with COVID-19 COD typically died of respiratory failure (75%) and tended to have fewer reported comorbidities (p = 0.029). Duration between first confirmed infection and death was negatively associated with COVID-19 being COD (p = 0.04). Repeated seroprevalence essays in a cross-sectional epidemiological study showed modest increases in seroprevalence over time, and substantial seroreversion (30%). IFR estimates accordingly varied depending on COVID-19 death attribution. Careful ascertainment of COVID-19 deaths is important in understanding the impact of the pandemic.

SARS-CoV-2 transmission in teenagers and young adults in Fútbol Club Barcelona's Multidisciplinary Sports Training Academy

Most studies, aimed at determining the incidence and transmission of SARS-CoV-2 in children and teenagers, have been developed in school settings. Our study conducted surveillance and inferred attack rates focusing on the practice of sports. Prospective and observational study of those attending the sports facilities of Fútbol Club Barcelona (FCB), in Barcelona, Spain, throughout the 2020-2021 season. Participants were young players (from five different sports) and adult workers, who belonged to stable teams (shared routines and were involved in same quarantine rules). Biweekly health questionnaires and SARS-CoV-2 screening were conducted. From the 234 participants included, 70 (30%) both lived and trained in the FCB facilities (Recruitment Pathway 1;RP1) and 164 (70%) lived at their own household and just came to the facilities to train (RP2). During the study, 38 positive cases were identified; none had severe symptoms or needed hospitalization. The overall weekly incidence in the cohorts did not differ compared to the one expected in the community, except for 2 weeks when an outbreak occurred. The attack rate (AR) was three times higher for the participants from RP1, in comparison to those from RP2 (p < 0.01). A Basketball team showed a significant higher AR.  Conclusion: Physical activities in stable teams are not related to an increased risk of transmission of SARS-CoV-2, since there were the same observed cases than expected in the community. The risk is higher in indoor sports (Basketball vs. Football), and in closed cohort living settings (RP1 vs. RP2). The fulfilment of preventive measures is essential. What is Known: • Despite the low numerical impact caused in paediatric hospitalizations during COVID-19 pandemic, the social impact has been maximum. • The transmission potential in children and teenagers is limited, and it had been widely demonstrated in school settings. What is New: • Group physical activities in children and teenagers are not also related to an increased risk of transmission of SARS-CoV-2, when preventive measures, such as washing hands, and screening protocols are applied. • Routine and semi-professional sports activities seem safe environments to promote during this pandemic.

Leveraging Serosurveillance and Postmortem Surveillance to Quantify the Impact of Coronavirus Disease 2019 in Africa

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has had a devastating impact on global health, the magnitude of which appears to differ intercontinentally: For example, reports suggest that 271 900 per million people have been infected in Europe versus 8800 per million people in Africa. While Africa is the second-largest continent by population, its reported COVID-19 cases comprise <3% of global cases. Although social and environmental explanations have been proposed to clarify this discrepancy, systematic underascertainment of infections may be equally responsible.

METHODS

We sought to quantify magnitudes of underascertainment in COVID-19's cumulative incidence in Africa. Using serosurveillance and postmortem surveillance, we constructed multiplicative factors estimating ratios of true infections to reported cases in Africa since March 2020.

RESULTS

Multiplicative factors derived from serology data (subset of 12 nations) suggested a range of COVID-19 reporting rates, from 1 in 2 infections reported in Cape Verde (July 2020) to 1 in 3795 infections reported in Malawi (June 2020). A similar set of multiplicative factors for all nations derived from postmortem data points toward the same conclusion: Reported COVID-19 cases are unrepresentative of true infections, suggesting that a key reason for low case burden in many African nations is significant underdetection and underreporting.

CONCLUSIONS

While estimating the exact burden of COVID-19 is challenging, the multiplicative factors we present furnish incidence estimates reflecting likely-to-worst-case ranges of infection. Our results stress the need for expansive surveillance to allocate resources in areas experiencing discrepancies between reported cases, projected infections, and deaths.

The humoral immune response more than one year after SARS-CoV-2 infection: low detection rate of anti-nucleocapsid antibodies via Euroimmun ELISA

PURPOSE

Antibody assays against SARS-CoV-2 are used in sero-epidemiological studies to estimate the proportion of a population with past infection. IgG antibodies against the spike protein (S-IgG) allow no distinction between infection and vaccination. We evaluated the role of anti-nucleocapsid-IgG (N-IgG) to identify individuals with infection more than one year past infection.

METHODS

S- and N-IgG were determined using the Euroimmun enzyme-linked immunosorbent assay (ELISA) in two groups: a randomly selected sample from the population of Stuttgart, Germany, and individuals with PCR-proven SARS-CoV-2 infection. Participants were five years or older. Demographics and comorbidities were registered from participants above 17 years.

RESULTS

Between June 15, 2021 and July 14, 2021, 454 individuals from the random sample participated, as well as 217 individuals with past SARS-CoV-2 infection. Mean time from positive PCR test result to antibody testing was 458.7 days (standard deviation 14.6 days) in the past infection group. In unvaccinated individuals, the seroconversion rate for S-IgG was 25.5% in the random sample and 75% in the past infection group (P = < 0.001). In vaccinated individuals, the mean signal ratios for S-IgG were higher in individuals with prior infection (6.9 vs 11.2; P = < 0.001). N-IgG were only detectable in 17.1% of participants with past infection. Predictors for detectable N-IgG were older age, male sex, fever, wheezing and in-hospital treatment for COVID-19 and cardiovascular comorbidities.

CONCLUSION

N-IgG is not a reliable marker for SARS-CoV-2 infection after more than one year. In future, other diagnostic tests are needed to identify individuals with past natural infection.

Impact of COVID-19 Vaccination on Seroprevalence of SARS-CoV-2 among the Health Care Workers in a Tertiary Care Centre, South India

Global vaccine development efforts have been accelerated in response to the devastating COVID-19 pandemic. The study aims to determine the seroprevalence of SARS-CoV-2 IgG antibodies among vaccine-naïve healthcare workers and to describe the impact of vaccination roll-out on COVID-19 antibody prevalence among the health care centers in tertiary care centers in South India. Serum samples collected from vaccinated and unvaccinated health care workers between January 2021 and April 2021were subjected to COVID-19 IgG ELISA, and adverse effects after the first and second dose of receiving the Covishield vaccine were recorded. The vaccinated group was followed for a COVID-19 breakthrough infection for a period of 6 months. Among the recruited HCW, 156 and 157 participants were from the vaccinated and unvaccinated group, respectively. The seroprevalence (COVID-19 IgG ELISA) among the vaccinated and unvaccinated Health Care Workers (HCW) was 91.7% and 38.2%, respectively, which is statistically significant. Systemic and local side-effects after Covishield vaccination occur at lower frequencies than reported in phase 3 trials. Since the COVID-19 vaccine rollout has commenced in our tertiary care hospital, seropositivity for COVID-19 IgG has risen dramatically and clearly shows trends in vaccine-induced antibodies among the health care workers.

Feasibility of At-Home Virological and Serological Testing for SARS-CoV-2 in Children

Longitudinal virological and serological surveillance is essential for understanding SARS CoV-2 transmission among children but requires increased test capacity. We assessed the uptake of serial at-home testing in children (2-17 years) via mailed SARS-CoV-2 antibody and molecular tests. Completion rates demonstrated feasibility and sustainability of at-home testing across age groups.

Findings of second multicentric follow-up serosurvey among Health Care Workers in government hospitals

Background

The change in serological status of community may be used as input for guiding the public health policy. Hence, the present study was conducted to determine change in seroprevalence of COVID-19 among healthcare workers (HCWs).

Methods

From the baseline multicentric study sample, a subsample was followed up, and a seroepidemiological study was conducted among them between 6 and 22 weeks after the second dose of the vaccination. Multistage population proportion to size sampling was performed for the selection of subsample of HCWs. The serosurvey was conducted using the enzyme-linked immunosorbent assay-based IgG antibody test (COVID KAVACH).

Results

Follow-up serological testing was done in subsample of 1122 participants of original 3253 participants. The mean age of the participants was 34.6 (8.13) years. A total of 300 (26.7%) participants were females. The seroprevalence was 78.52, (95%CI:76-80.1). Among those who were seronegative at initial test, 708 (77.04%) were seroconverted. Those who were not seroconverted (241 (21.5%)) have longer duration from the second dose of the vaccination (93 (31.4) vs. 56 (38.4); p value < 0.001). The COVID-19 infection was significantly associated with seropositive status and being a medical staff was associated with remaining seronegative on follow-up. The higher age (≥50 years) was found to be significantly associated with seroreversion.

Conclusion

Four in five HCWs had detectable antibodies. Seroepidemiological studies carry vital information to control the public health response in the course of the pandemic. The study can also further help as a platform to study the seroconversion and effect of vaccination among HCWs for newer variants of SARS-CoV-2.

Infection fatality rate of COVID-19 in community-dwelling elderly populations

This mixed design synthesis aimed to estimate the infection fatality rate (IFR) of Coronavirus Disease 2019 (COVID-19) in community-dwelling elderly populations and other age groups from seroprevalence studies. Protocol: https://osf.io/47cgb. Eligible were seroprevalence studies done in 2020 and identified by any of four existing systematic reviews; with ≥ 500 participants aged ≥ 70 years; presenting seroprevalence in elderly people; aimed to generate samples reflecting the general population; and whose location had available data on cumulative COVID-19 deaths in elderly (primary cutoff ≥ 70 years; ≥ 65 or ≥ 60 also eligible). We extracted the most fully adjusted (if unavailable, unadjusted) seroprevalence estimates; age- and residence-stratified cumulative COVID-19 deaths (until 1 week after the seroprevalence sampling midpoint) from official reports; and population statistics, to calculate IFRs adjusted for test performance. Sample size-weighted IFRs were estimated for countries with multiple estimates. Thirteen seroprevalence surveys representing 11 high-income countries were included in the main analysis. Median IFR in community-dwelling elderly and elderly overall was 2.9% (range 1.8–9.7%) and 4.5% (range 2.5–16.7%) without accounting for seroreversion (2.2% and 4.0%, respectively, accounting for 5% monthly seroreversion). Multiple sensitivity analyses yielded similar results. IFR was higher with larger proportions of people > 85 years. The IFR of COVID-19 in community-dwelling elderly is lower than previously reported.

The Impact of SARS-CoV-2 Primary Vaccination in a Cohort of Patients Hospitalized for Acute COVID-19 during Delta Variant Predominance

Vaccine breakthrough SARS-CoV-2 infections necessitating hospitalization have emerged as a relevant problem with longer time interval since vaccination and the predominance of the Delta variant. The aim of this study was to evaluate the association between primary vaccination with four SARS-CoV-2 vaccines authorized for use in the European Union—BNT162b2, ChAdOx-1S, mRNA-1273 or Ad.26.COV2.S—and progression to critically severe disease (mechanical ventilation or death) and duration of hospitalization among adult patients with PCR-confirmed acute COVID-19 hospitalized during the Delta variant predominance (October–November 2021) in Slovenia. Among the 529 enrolled patients hospitalized with COVID-19 (median age, 65 years; 58.2% men), 175 (33.1%) were fully vaccinated at the time of symptom onset. Compared with 345 unvaccinated patients, fully vaccinated patients with breakthrough infections were older, more often immunocompromised, and had higher Charlson comorbidity index scores. After adjusting for sex, age, and comorbidities, fully vaccinated patients had lower odds for progressing to critically severe disease and were discharged from the hospital earlier than unvaccinated patients. Vaccination against SARS-CoV-2 remains an extremely effective intervention to alleviate morbidity and mortality in COVID-19 patients.

Durability of Humoral Immune Responses to SARS-CoV-2 in Citizens of Ariano Irpino (Campania, Italy): A Longitudinal Observational Study With an 11.5-Month Follow-Up

As of November 17, 2021, SARS-CoV-2 (Severe Acute Respiratory Syndrome CoronaVirus 2), the causative agent of COVID-19 (COronaVIrus Disease 19), has infected ~250 million people worldwide, causing around five million deaths. Titers of anti-SARS-CoV-2 neutralizing antibodies were relatively stable for at least 9 months in a population-based study conducted in Wuhan, China, both in symptomatic and in asymptomatic individuals. In the mass screening campaign conducted in the town of Ariano Irpino (Avellino, Italy) in May, 2020, 5.7% (95% CI: 5.3-6-1) of the 13,444 asymptomatic citizens screened were positive for anti-nucleocapsid antibodies against SARS-CoV-2. Among these, 422 citizens were re-tested for anti SARS-CoV-2 antibodies in January, 2021 and/or in April, 2021 and enrolled in this longitudinal observational study. Median (interquartile range) age of the study cohort was 46 years (29–59), with 47 (11.1%) participants of minor age, while 217 (51.4%) participants were females. There was no evidence of re-infection in any of the subjects included. Presence of anti-nuclear antibodies antibodies (Elecysis, Roche) was reported in 95.7 and 93.7% of evaluable participants in January and April, 2021. Multiple logistic regression analysis used to explore associations between age, sex and seroprevalence showed that adults vs. minors had significantly lower odds of having anti-S1 antibodies (Biorad) both in January, 2021 and in April, 2021. Our findings showed that antibodies remained detectable at least 11.5 months after infection in >90% of never symptomatic cases. Further investigation is required to establish duration of immunity against SARS-CoV-2.

Waning of Anti-spike Antibodies in AZD1222 (ChAdOx1) Vaccinated Healthcare Providers: A Prospective Longitudinal Study

Introduction Coronavirus disease 2019 (COVID-19) vaccines are nothing short of a miracle story halting the pandemic across the globe. Nearly half of the global population has received at least one dose. Nevertheless, antibody levels in vaccinated people have shown waning, and breakthrough infections have occurred. Our study aims to measure antibody kinetics following AZD1222 (ChAdOx1) vaccination six months after the second dose and the factors affecting the kinetics. Materials and methods We conducted a prospective longitudinal study monitoring for six months after the second of two AZD1222 (ChAdOx1) vaccine doses in healthcare professionals and healthcare facility employees at Veer Surendra Sai Institute of Medical Sciences and Research (included doctors, nurses, paramedical staff, security and sanitary workers, and students). Two 0.5-mL doses of the vaccine were administered intramuscularly, containing 5 x 1010 viral particles 28 to 30 days between doses. We collected blood samples one month after the first dose (Round 1), one month after the second dose (Round 2), and six months after the second dose (Round 3). We tested for immunoglobulin G (IgG) levels against the receptor-binding domain of the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by chemiluminescence microparticle immunoassay. We conducted a linear mixed model analysis to study the antibody kinetics and influencing factors. Results Our study included 122 participants (mean age, 41.5 years; 66 men, 56 women). The geometric mean IgG titers were 138.01 binding antibody units (BAU)/mL in Round 1, 176.48 BAU/mL in Round 2, and 112.95 BAU/mL in Round 3. Seven participants showed seroreversion, and 11 had breakthrough infections. Eighty-six participants showed a substantial decline in antibody titer from Rounds 2 to 3. Persons aged 45 or older had higher mean titer than people aged younger than 45 years. Overweight and obese (BMI ≥ 25 kg/m2) had a higher mean titer than average or underweight persons. The only significant predictor of IgG titers at six months was SARS-CoV-2 infection on mixed model analysis. Conclusion We found a substantial decline in antibody levels leading to seven cases of seroreversion in healthcare professionals who received the ChAdOx1 vaccine. History of prior COVID-19 was the only significant factor in antibody levels at six months. Seroreversion and breakthrough infection warrant further research into the optimal timing and potential benefits of booster doses of the AZD1222 (ChAdOx1) COVID-19 vaccine.