COVID-19 Seroprevalence Research Articles

The value of using COVID-19 antibody tests as a potential approach to prioritize vaccination delivery.

The highly contagious novel COVID-19 virus has demonstrated a great challenge for healthcare workers (HCWs) worldwide. One of these challenges is the availability of vaccines in some countries or societies, especially in the early stages of the pandemic. This study aims to determine the level of natural immunity against COVID-19 infection among HCWs exposed to COVID-19 at the early stages of the pandemic and build a model to determine the groups that can benefit more from the scarce vaccination resources. This study took place between January and March 2021, after the first waves of the COVID-19 pandemic, before spreading the variants of concern, such as the UK variant (Alpha B.1.1.7), and before starting the vaccine campaigns. This cross-sectional study collected serum samples from 251 vulnerable HCWs. The samples were tested for IgG antibodies against COVID-19 using commercial kits. The demographics and clinical characteristics of the participants were recorded using face-to-face interviews. COVID-19 IgG antibodies were detected in more than 40% of HCWs before vaccination. Those HCWs should have less priority than those without COVID-19 IgG. The seroprevalence of COVID-19 was higher in male HCWs and among nurses. There was no association between the participants' immunity and smoking status or different blood groups. Most HCWs reported being infected with the virus during the first wave, mainly at the end of 2020. A limited number of HCWs reported infections between January 2021 and March 2021. All HCWs eventually received the COVID-19 vaccine, ignoring being previously infected. The reported results emphasize the value of using immunity tests to prioritize the groups that may benefit the most from the limited vaccines, especially in developing countries with scarce resources where those with COVID-19 IgG antibodies should have less priority for the COVID-19 vaccine. The present results indicate that up to 40% of the delivered vaccines to HCWs who had COVID-19 antibodies could be prioritized more wisely in future pandemics.

Desenlaces materno-perinatales en unapoblación de gestantes con infección porCOVID-19 en un hospital de Lima, Perú

Introduction: COVID-19 has impacted obstetric field, affecting pregnant women with risks such as preterm birth, preeclampsia, and perinatal complications. Objective: To describe the characteristics of a population of pregnant women with COVID-19 infection, the characteristics of their newborns, and perinatal outcomes at National Hospital Edgardo Rebagliati between March and June 2020, Lima, Peru. Materials and methods: Observational cross-sectional study, from March to June 2020. All pregnant women who arrived at the obstetricemergency and were hospitalized at the Rebagliati Hospital were included and underwent an immunochromatography test for IgM/IgG to determine the seroprevalence of COVID-19 and/ or PCR. Obstetric and perinatal variables were collected in a data sheet on admission to the emergency room and hospitalization. Results: Rapid test for SARS-CoV-2 was performed in 108 pregnant women hospitalized for delivery, 106 singleton pregnancies (98%) and 2 twins(2%). The average age was 31 years, with 1% of adolescents and 33% over 35 years; 46% ofdeliveries were vaginal, 18,5% of them preterm; 37% of the pregnant women were symptomatic and 7,4% were admitted to the intensive care unit. 91,8% of the newborns weighed between 2500 and 3999g, 51% were female, 93,5 % had Apgar greater than 7 at one minute and 100% with negative swabbing in newborns within the first 24 to 72 hours. Conclusion: Most of the pregnant women were asymptomatic and 3 out of 100 pregnant women had respiratorycomplications. The prevalence of cesarean section was low in relation to other publications, 2 of the newborns had positive swabs with possible horizontal transmission.

VIVALDI Cohort Profile: Using linked, routinely collected data and longitudinal blood sampling to characterise COVID-19 infections, vaccinations, and related outcomes in care home staff and residents in England.

VIVALDI (ISRCTN14447421) is a government-funded longitudinal open observational cohort study of staff and residents in care homes for older people in England. The study aimed to describe epidemiology (including seroprevalence) and immune responses to COVID-19 in a subset of care homes, in the context of extremely high mortality in this setting, in the first 12-18 months of the pandemic. Data linkage to routine health data was undertaken for all staff and residents and a subset of individuals who consented to sequential blood sampling to investigate SARS-CoV-2 immunity. This paper aims to describe the samples stored within the VIVALDI biobank and associated linked data, available for use by researchers. Over 70,000 individuals from 346 care homes were included in the data linkage cohort (1 st March 2020-31 st March 2023). 4971 samples from 2264 individuals (1415 staff, 827 residents) collected between 29 th October 2020 and 10 th March 2023 are stored. Amongst these samples, there was a maximum of seven per participant however, 217 (26.2%) residents and 551 (38.9%) staff participated in one round only. Key study findings include high COVID-19 seroprevalence among surviving residents, exceeding rates in community-dwelling peers. COVID-19 vaccinations generated robust immune responses in staff and residents which waned, supporting the need for booster vaccination, particularly in response to new variants. Prior infection significantly improved vaccine-induced immune responses, however protection from infection declined following Omicron variant emergence. This is a unique cohort of pre- and post-infection samples linked to data on COVID-19 infections, vaccinations, and outcomes. The cohort spans host immune response evolution to infection and vaccination in this rarely sampled population of frail older care home residents who are especially vulnerable to infection and severe outcomes. These samples can be used to investigate biological mechanisms behind disparate infection responses in older people and make a valuable contribution to research into ageing.

Assessment of COVID-19 Knowledge, Vaccination Rates and Seroprevalence among Female Sex Workers in Burkina Faso, 2022

Assessment of COVID-19 Knowledge, Vaccination Rates and Seroprevalence among Female Sex Workers in Burkina Faso, 2022

COVID-19 seroprevalence estimation and forecasting in the USA from ensemble machine learning models using a stacking strategy

The COVID-19 pandemic exposed the importance of research on the spread of epidemic diseases. In this paper, we apply Artificial Intelligence and statistics techniques to build prediction models to estimate the SARS-CoV-2 seroprevalence in the United States, using multiple estimates of COVID-19 prevalence and other explanatory variables. We propose the use of stacking techniques based on multiple model building techniques (Linear and Beta Regression, Genetic Programming and Neural Networks) to obtain Predictive Ensemble Models. There has been extensive research on this field, but there has not been in-depth research on the application of stacking methods to estimate and forecast seroprevalence in the USA specifically. This paper provides a novel comparison of the behaviour and performance of different building techniques for stacking ensemble models and presents which methods are better for different scenarios. We find that Genetic Programming and Neural Networks are the best models with trained data within single states, and when multiple states are considered Genetic Programming is still better than the Regression models, but Neural Networks fail to estimate the seroprevalence accurately. Another novelty of our work is the use of cross-state validation to evaluate the models with new data, as well as temporal forecasting. Depending on how the data is processed, Linear Regression performs very well with cross-state validation and temporal forecasting, and Genetic Programming is very accurate with the former while Neural Networks work better with the latter.

Seroprevalence and risk factors for SARS-CoV-2 infection in middle-sized cities of Burkina Faso: A descriptive cross-sectional study.

Since March 2020, COVID-19 has evolved from a localized outbreak to a global pandemic. We assessed the seroprevalence of COVID-19 in three towns in the Centre Sud region of Burkina Faso. A population-based cross-sectional survey was conducted in three middle-sized cities in Burkina Faso's Centre Sud region, from June to July 2021. Subjects aged 16 or over at the time of the survey were considered for this seroprevalence study. The Biosynex COVID-19 BSS rapid test was used to detect immunoglobulin G (IgG) and immunoglobulin M (IgM) against SARS-CoV-2. A standardized questionnaire was also administered to collect additional information. A total of 2449 eligible participants (age ≥ 16 years) were identified. Serological tests for COVID-19 were performed in 2155 individuals, of which 2143 valid tests were retained and analyzed. Out of the entire sample, 246 positive tests were observed, corresponding to a prevalence of 11.48%. Prevalence was 9.35% (58 cases) in Kombissiri, 12.86% (80 cases) in Manga and 11.99% (108 cases) in Pô. By gender, 13.37% of women (164 cases) tested positive, and 8.95% of men (82 cases). Women accounted for 66.67% of all positive test subjects. The results from the multivariate analysis show a significantly higher seroprevalence in women (p = 0.007), people over 55 years old (p = 0.004), overweight people (p = 0.026) and those with drinking water sources at home (p = 0.013). The results of this study show that the COVID-19 virus also circulates in the population of middle-sized cities in Burkina Faso, far more than officially reported by the information service of the government of Burkina Faso, given the lack of systematic testing in the general population in the country. The study also highlighted the greater vulnerability of women, older and overweight individuals to the epidemic. The preventive measures put in place to fight the pandemic must take these different factors into account.

Sociodemographic influences on private and professional contact behaviour during the COVID-19 pandemic in Germany: cross-sectional analysis based on a Regional Blood Donor Cohort

ObjectiveThe COVID-19 pandemic has had significant health and socioeconomic impacts worldwide. Extensive measures, including contact restrictions, were implemented to control the spread of the virus. This study aims to examine the factors that influenced private and professional contact behaviour during the COVID-19 pandemic.ResultsWe used baseline data (January–April 2021) from the SeMaCo study (Serologische Untersuchungen bei Blutspendern des Großraums Magdeburg auf Antikörper gegen SARS-CoV-2), a longitudinal, regional cohort study assessing COVID-19 seroprevalence in blood donors from Magdeburg and surrounding areas in Germany. In the blood donor cohort (n = 2,195), there was a general reduction in private contacts (by 78.9%) and professional contacts (by 54.4%) after March 18, 2020. Individuals with higher education reduced both private (by 84.1%) and professional (by 70.1%) contacts more than those with lower education levels (private contacts 59.5%; professional contacts 37%). Younger age groups (18–30 years) reduced private contacts more frequently (by 85.4%) than older individuals (61–83 years, by 68.6%) and demonstrated a higher likelihood of private contact reduction compared to older age groups (51–60 years: odds ratio (OR) 0.45 [95% [CI] 0.32–0.65]; 61–83 years: OR 0.33 [95% [CI] 0.22–0.48]).

Pandemic burden in low-income settings and impact of limited and delayed interventions: A granular modelling analysis of COVID-19 in Kabwe, Zambia

ObjectivesPandemic response in low-income countries (LICs) or settings often suffers from scarce epidemic surveillance and constrained mitigation capacity. The drivers of pandemic burden in such settings, and the impact of limited and delayed interventions remain poorly understood. MethodsWe analysed COVID-19 seroprevalence and all-cause excess deaths data from the peri-urban district of Kabwe, Zambia between March 2020 and September 2021 with a novel mathematical model. Data encompassed three consecutive waves caused by the wild-type, Beta and Delta variants. ResultsAcross all three waves, we estimated a high cumulative attack rate, with 78% (95% credible interval [CrI] 71-85) of the population infected, and a high all-cause excess mortality, at 402 (95% CrI 277-473) deaths per 100,000 people. Ambitiously improving health care to a capacity similar to that in high-income settings could have averted up to 46% (95% CrI 41-53) of accrued excess deaths, if implemented from June 2020 onward. An early and accelerated vaccination rollout could have achieved the highest reductions in deaths. Had vaccination started as in some high-income settings in December 2020 and with the same daily capacity (doses per 100 population), up to 68% (95% CrI 64-71) of accrued excess deaths could have been averted. Slower rollouts would have still averted 62% (95% CrI 58-68), 54% (95% CrI 49-61) or 26% (95% CrI 20-38) of excess deaths if matching the average vaccination capacity of upper-middle-, lower-middle- or LICs, respectively. ConclusionsRobust quantitative analyses of pandemic data are of pressing need to inform future global pandemic preparedness commitments.

Evolución de la seroprevalencia de COVID-19 en bancos de sangre durante la pandemia en la región Lima, Perú

Introduction. Peru was one of the countries most affected by the COVID-19 pandemic, with more than 220,000 deaths recorded due to SARS-CoV-2 infection. Given the constant mutations of the virus and registered variants, it is important to carry out research that reflects the evolution of the humoral immune state. Objective. Measure the seroprevalence of COVID-19 during the pandemic in the department of Lima in the period between April 1, 2020 and June 30, 2022, in donor samples from 6 hospital blood banks public of Lima, Peru. Methods. A descriptive, transversal, observational and retrospective study was carried out evaluating the presence of IgM/IgG antibodies against SARS-CoV-2 using lateral flow chromatographic immunoassay in samples from healthy and asymptomatic donors from blood banks of 6 health facilities in the department of Lima. Results. A progressive increase in the seroprevalence of IgG and total reactivity of IgM/ IgG antibodies against SARS-CoV-2 will be observed as follows: 22,6% - 32,7% during 2020; 53,9% - 58,1% during 2021; 88,9% - 93,3% during the first half of 2022. Conclusions. The reactivity and presence of anti- SARS-CoV-2 antibodies progressively increase during the COVID-19 pandemic from 11,2% to 98,4% in the samples evaluated, possibly with the impact of the pandemic waves and the active vaccination campaign against COVID-19.

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

IntroductionSerological 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.MethodsA 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.ResultsThe 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)).ConclusionSARS-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.

The seroprevalence of COVID-19 among people living with HIV in Morocco

The association of COVID-19 and HIV infection would seem deadly in terms of prognosis and the possibilities of viral clearance given the immunodeficiency. However, a lower seroprevalence has been reported in some studies compared to that found in the non-HIV population. The objective of this study is to determine the seroprevalence of COVID-19 among people living with HIV (PLHIV) in Morocco. This is a prospective study carried out in the infectious diseases department of the Ibn Rochd University Hospital in Casablanca. We included PLHIV who consulted the Infectious Diseases Day-Hospital service between January 18, 2021 and March 10, 2021. After informed consent, patients completed a survey and had blood drawn for SARS-CoV-2 antibody testing. The determination of IgG antibodies against SARS-CoV-2 in blood was carried out using chemiluminescence microparticle immunoassay technology. We included 418 PLHIV in the study, most patients were male (50.24%), the average age was 40 years, 90.2% of patients were on antiretroviral treatment, 56.7% had a viral load &lt;20 copies/ml, and 47.37% had a CD4 count greater than 500 cells/μL. The IgG test was positive in 53 patients, representing a seroprevalence of 12.68%. None of the patients had clinical signs. Seroprevalence was higher in female patients (58.49%), aged between 30 and 40 years (41.51%), in patients with a negative viral load (64.15%) and a CD4 count greater than 500 cells/mm3 (49.6%). Our study showed that the seroprevalence of COVID-19 was higher among PLHIV compared to people without HIV infection. All the patients had asymptomatic forms which pushes us to evoke a theory, to demonstrate, of the action of antiretrovirals against SARS-CoV-2.

Comparing frequency of booster vaccination to prevent severe COVID-19 by risk group in the United States

There is a public health need to understand how different frequencies of COVID-19 booster vaccines may mitigate the risk of severe COVID-19, while accounting for waning of protection and differential risk by age and immune status. By analyzing United States COVID-19 surveillance and seroprevalence data in a microsimulation model, here we show that more frequent COVID-19 booster vaccination (every 6–12 months) in older age groups and the immunocompromised population would effectively reduce the burden of severe COVID-19, while frequent boosters in the younger population may only provide modest benefit against severe disease. In persons 75+ years, the model estimated that annual boosters would reduce absolute annual risk of severe COVID-19 by 199 (uncertainty interval: 183–232) cases per 100,000 persons, compared to a one-time booster vaccination. In contrast, for persons 18–49 years, the model estimated that annual boosters would reduce this risk by 14 (10–19) cases per 100,000 persons. Those with prior infection had lower benefit of more frequent boosting, and immunocompromised persons had larger benefit. Scenarios with emerging variants with immune evasion increased the benefit of more frequent variant-targeted boosters. This study underscores the benefit of considering key risk factors to inform frequency of COVID-19 booster vaccines in public health guidance and ensuring at least annual boosters in high-risk populations.

Missing data and missed infections: investigating racial and ethnic disparities in SARS-CoV-2 testing and infection rates in Holyoke, Massachusetts.

Routinely collected testing data have been a vital resource for public health response during the COVID-19 pandemic and have revealed the extent to which Black and Hispanic persons have borne a disproportionate burden of SARS-CoV-2 infections and hospitalizations in the United States. However, missing race and ethnicity data and missed infections due to testing disparities limit the interpretation of testing data and obscure the true toll of the pandemic. We investigated potential bias arising from these 2 types of missing data through a case study carried out in Holyoke, Massachusetts, during the prevaccination phase of the pandemic. First, we estimated SARS-CoV-2 testing and case rates by race and ethnicity, imputing missing data using a joint modeling approach. We then investigated disparities in SARS-CoV-2 reported case rates and missed infections by comparing case rate estimates with estimates derived from a COVID-19 seroprevalence survey. Compared with the non-Hispanic White population, we found that the Hispanic population had similar testing rates (476 tested per 1000 vs 480 per 1000) but twice the case rate (8.1% vs 3.7%). We found evidence of inequitable testing, with a higher rate of missed infections in the Hispanic population than in the non-Hispanic White population (79 infections missed per 1000 vs 60 missed per 1000).

Investigating the Antibody Imprinting Hypothesis among Canadian Paramedics after SARS-CoV-2 Omicron Variant Circulation.

Recent research has highlighted the Omicron variant's capacity to evade immune protection conferred by wild-type (WT) mRNA vaccines. Despite this observation, the potential involvement of antigenic sin phenomena remains unclear. Our hypothesis posited that a greater number of prior WT vaccine doses might lead to reduced anti-Omicron neutralization Abs following Omicron infection. To investigate this, we analyzed blood samples from human participants in the COVID-19 Occupational Risk, Seroprevalence, and Immunity among Paramedics (CORSIP) study who had received at least one WT mRNA vaccine before contracting Omicron. The exposure variable was the number of WT mRNA vaccines administered, and the outcome was the angiotensin-converting enzyme 2 (ACE-2) percent inhibition specific to the BA.4/BA.5 Omicron Ag. Contrary to expectations, our findings revealed that more WT-based vaccines were associated with an enhanced Omicron-specific immune response.

Association of lifestyle and flourishing during the COVID-19 pandemic in Japan.

COVID-19 have changed our lifestyle and little is known how our lifestyle associated with flourishing during COVID-19. This study examined the association between lifestyle, including sleep time, drinking, and smoking, and flourishing during the COVID-19 pandemic in Japan. We used the population-based study, Utsunomiya COVID-19 seROprevalence Neighborhood Association (U-CORONA) survey conducted in November 2021 to examine the association between lifestyle such as sleeping time, drinking and smoking, and flourishing (n = 473). Flourishing was assessed with the flourishing index, a 10-item multidimensional scale with five domains. Multivariate linear regression analysis was performed adjusted for sex, age, income, and education. We found that the flourishing index was significantly lower in the group that slept less than 6 h than in the group that slept 6-8 h (coef = -0.49, SE = 0.17, p < 0.01). We also found that drinking once to several times/week showed higher flourishing than those who almost never drink (coef = 0.57, SE = 0.19, p < 0.01). Smoking was not associated with flourishing. Sleep duration and drinking habit, but not smoking, may be important for flourishing during the COVID-19 pandemic.

Effects of rurality and distance to care on perinatal outcomes over a 1-year period during the COVID-19 pandemic.

Our aim was to investigate the roles of rurality and distance to care on adverse perinatal outcomes and COVID-19 seroprevalence at the time of delivery over a 1-year period. Data were collected from the electronic medical record on all pregnant patients who delivered at a single, large, Midwest academic medical center over 1 year. Rurality was classified using standard Rural-Urban Commuting Area codes. Geographic Information System tools were used to map outcomes. Data were analyzed with univariate and multivariate models, controlling for Body Mass Index (BMI), insurance status, and parity. A total of 2,497 patients delivered during the study period; 20% of patients were rural (n = 499), 18.6% were micropolitan (n = 466), and 61.4% were metropolitan (n = 1,532). 10.4% of patients (n = 259) were COVID-19 seropositive. Rural patients did not experience higher rates of any measured adverse outcomes than metropolitan patients; micropolitan patients had increased odds of preterm labor (OR = 1.41, P = .022) and pre-eclampsia (OR = 1.78, P<.001). Patients living 30+ miles away from the medical center had increased odds of preterm labor (OR = 1.94, P<.001), pre-eclampsia (OR = 1.73, P = .002), and infant admission to the neonatal intensive care unit (OR = 2.12, P<.001), as well as lower gestational age at delivery (β = -9.2 days, P<.001) and birth weight (β = -206 grams, P<.001). Distance to care, rather than rurality, was the key predictor of multiple adverse perinatal outcomes in this cohort of deliveries over a 1-year period. Our study suggests that rurality should not be used as a standalone indicator of access to care without further knowledge of the specific barriers affecting a given population.

Effect of Vaccination on Seroprevalence of COVID-19 among Blood donors - A cross-sectional Analytic Study from South India.

India achieved impressive strides by providing 1.7billion doses of the COVID-19 vaccine to more than 940million people, attaining 100% first dose coverage and 80% overall immunization coverage as of February 9, 2022. Compared to unvaccinated individuals, vaccinated people have considerably decreased risks of infection, serious illness, hospitalization, and death. With the help of this study, we determined the prevalence of COVID-19 IgG antibodies with respect to vaccination. The cross-sectional analytical study was conducted from July 2021 to April 2022 on 809 healthy donors. All donor samples were screened for COVID-19 IgG antibodies against S1 protein using IgG ELISA kits (Qualisa COVID-19 IgG kits, Tulip, Goa, India). Data regarding COVID-19 infection history, vaccination status, type of vaccine, and the number of doses were obtained. All data were entered in Microsoft Excel and analyzed using SPSS version 21. Out of 809 blood donors, a total of 650 participants were vaccinated, among which 89.5% had COVID-19 IgG antibodies and 10.5% had no antibodies. Out of the 159 who had not taken vaccination, 52.8% of the participants had COVID-19 IgG antibodies, and 47.2% of the donors had no COVID-19 IgG antibodies. A total of 617 participants have taken the Covishield vaccine, of which 90.2% had COVID-19 IgG antibodies. A total of 32 donors have taken Covaxin, of which 78.1% had COVID-19 IgG antibodies. The above study has shown that COVID-19 vaccination enhances covid antibody formation, and multiple doses of vaccine ensure longevity of these antibodies.

Riding high: seroprevalence of SARS-CoV-2 after 4 pandemic waves in Manitoba, Canada, April 2020–February 2022

BackgroundCanada is emerging from the largest SARS-CoV-2 Omicron wave to date, with over 3.3 million confirmed cases. Unfortunately, PCR confirmed cases illuminate only a small portion of infections in the community and underestimate true disease burden. Population based seroprevalence studies, which measure antibody levels against a virus can more accurately estimate infection rates in the community and identify geographical and epidemiological trends to inform public health responses.MethodsThe Manitoba COVID-19 Seroprevalence (MCS) study is a population-based cross-sectional study to assess the prevalence of SARS-CoV-2 antibodies across the province. Residual convenience specimens (n = 14,901) were tested for anti-SARS-CoV-2 nucleocapsid and spike IgG antibodies from April 1, 2020 to February 31, 2022. We estimated the monthly and cumulative prevalence using an exponential decay model, accounting for population demographics, sensitivity/specificity, and antibody waning. This approach generated estimates of natural infection as well as total antibody including vaccine-induced immunity within the community.FindingsAfter four waves of the pandemic, 60.1% (95%CI-56.6–63.7) of Manitobans have generated SARS-CoV-2 antibodies due to natural exposure independent of vaccination. Geographical analysis indicates a large portion of provincial prevalence stems from increased transmission in the Northern (92.3%) and Southern (71.8%) regional health authorities. Despite the high mortality rates reported by Manitoba, infection fatality ratios (IFR) peaked at 0.67% and declined to 0.20% following the Omicron wave, indicating parity with other national and international jurisdictions. Manitoba has achieved 93.4% (95%CI- 91.5–95.1) total antibody when including vaccination.InterpretationOur data shows that more than 3 in 5 Manitobans have been infected by SARS-CoV-2 after four waves of the pandemic. This study also identifies key geographical and age specific prevalence rates that have contributed greatly to the overall severity of the pandemic in Manitoba and will inform jurisdictions considering reduction of public health measures.

Prevalence of SARS-CoV-2 infection among USblood donors by industry, May-December 2021.

Work is a social determinant of health that is often overlooked. There are major work-related differences in the risk of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) infection and death, but there have been few analyses of infection rates across industry groups. To date, only one national assessment of SARS-CoV-2 infection prevalence by industry based on self-report has been completed. No study has looked at seroprevalence of COVID-19 by industry. During May-December 2021, blood donors with SARS-CoV-2 antinucleocapsid testing were sent an electronic survey about their work. Free-text industry responses were classified using the North American Industry Classification System. We estimated seroprevalence and 95% confidence intervals (CIs) of SARS-CoV-2 infection by industry. Of 57,726 donors, 7040 (12%, 95% CI: 11.9%-12.5%) had prior SARS-CoV-2 infection. Seroprevalence was highest among Accommodation & Food Services (19.3%, 95% CI: 17.1%-21.6%), Mining, Quarrying, and Oil and Gas Extraction (19.2%, 95% CI: 12.8%-27.8%), Healthcare & Social Assistance (15.6%, 95% CI: 14.9%-16.4%), and Construction (14.7%, 95% CI: 13.1%-16.3%). Seroprevalence was lowest among Management of Companies & Enterprises (6.5%, 95% CI: 3.5%-11.5%), Professional Scientific & Technical Services (8.4%, 95% CI: 7.7%-9.0%), and Information (9.9%, 95% CI: 8.5%-11.5%). While workers in all industries had serologic evidence of SARS-CoV-2 infection, certain sectors were disproportionately impacted. Disease surveillance systems should routinely collect work characteristics so public health and industry leaders can address health disparities using sector-specific policies.

VIVALDI Cohort Profile: Using linked, routinely collected data and longitudinal blood sampling to characterise COVID-19 infections, vaccinations, and related outcomes in care home staff and residents in England

VIVALDI (ISRCTN14447421) is a government-funded longitudinal open observational cohort study of staff and residents in care homes for older people in England. The study aimed to describe epidemiology (including seroprevalence) and immune responses to COVID-19 in a subset of care homes, in the context of extremely high mortality in this setting, in the first 12-18 months of the pandemic. Data linkage to routine health data was undertaken for all staff and residents and a subset of individuals who consented to sequential blood sampling to investigate SARS-CoV-2 immunity. This paper aims to describe the samples stored within the study biobank, available for use by researchers. Over 70,000 individuals from 346 care homes were included in the data linkage cohort (1st March 2020–31st March 2023). 4975 samples from 2268 individuals (1419 staff, 827 residents) collected between 29th October 2020 and 10th March 2023 are stored. Amongst these samples, there was a maximum of seven per participant however, 217 (26.2%) residents and 555 (39.1%) staff participated in one round only. Key study findings include high COVID-19 seroprevalence among surviving residents, exceeding rates in community-dwelling peers. COVID-19 vaccinations generated robust immune responses in staff and residents which waned, supporting the need for booster vaccination, particularly in response to new variants. Prior infection significantly improved vaccine-induced immune responses, however protection from infection declined following Omicron variant emergence. This is a unique cohort of pre- and post-infection samples linked to data on COVID-19 infections, vaccinations, and outcomes. The cohort spans host immune response evolution to infection and vaccination in this rarely sampled population of frail older care home residents who are especially vulnerable to infection and severe outcomes. These samples can be used to investigate biological mechanisms behind disparate infection responses in older people and make a valuable contribution to research into ageing.