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Trajectories of SARS-CoV-2 IgG antibodies and ACE2r-blocking (neutralizing activity) as measured by a virus-free assay, from March 2022 to June/July 2022. NuC, nucleocapsid; IgG, immunglobulin G. Seropositivity is defined based on the presence of anti-spike IgG antibodies according to the threshold of SenASTrIS test positivity with median fluorescence intensity (MFI) 6. Neutralization capacity based on virus-free assay with cut-off value of 50. Participants of Corona Immunitas from Ticino and Zurich, Switzerland (n ¼ 1702)
Source publication
Background
Seroprevalence and the proportion of people with neutralizing activity (functional immunity) against SARS-CoV-2 variants were high in early 2022. In this prospective, population- based, multi-region cohort study, we assessed the development of functional and hybrid immunity (induced by vaccination and infection) in the general population...
Citations
... A recent systematic review indicated that prevalence estimates based solely on standardized instruments are about double as high as prevalence estimates based on standardized diagnostic interviews [18]. We will take this challenge into account in different ways: First, we will provide prevalence estimates and 95% credible intervals using a Bayesian logistic regression model adjusted for age-group and cluster of oblasts taking sensitivity and specificity of the instruments, as described above, and their uncertainty into account [33,34]. ...
... This sample size provides 95% confidence intervals of ±6%-7% when analysing the results separately for women and men, age groups and cluster of oblasts. Sample size calculations were performed using the Scalex SP calculator [34]. ...
Objectives
To conduct mental health surveillance in adults in Ukraine and Ukrainian refugees (Canton of Zurich, Switzerland) as an actionable scientific foundation for public mental health and mental healthcare.
Methods
Mental Health Assessment of the Population (MAP) is a research program including prospective, population-based, digital cohort studies focused on mental health monitoring. The study aims to include 17,400 people from the general population of Ukraine, 1,220 Ukrainians with refugee status S residing in the canton of Zurich, and 1,740 people from the Zurich general population. The primary endpoints are prevalence and incidence of symptoms of: posttraumatic stress disorder (measured by PCL-5), depression (PHQ-9), anxiety (GAD-7), and alcohol use disorder (AUDIT). Secondary endpoints include participants’ health-related quality of life (EQ-5D-5L and EQ-VAS), experiences of somatic distress syndrome (PHQ-15), social isolation, social integration, and mental wellbeing (SWEMWBS).
Results
Baseline assessment starts in March 2024 with follow-ups occurring every 3 months for at least 2 years.
Conclusion
MAP will generate reliable, comparable, and high-quality epidemiological data to inform public mental health and healthcare policies in the Ukrainian population.
ISRCTN Registry
https://www.isrctn.com/ISRCTN17240415 .
... Corona Immunitas is a nation-wide Swiss research program of cross-sectional and longitudinal SARS-CoV-2 seroprevalence studies that investigated the spread and impact of infection with SARS-Cov-2 in Switzerland over six phases (https://www.corona-immunitas.ch/en/). [22][23][24][25][26] To ensure comparability, a standardized protocol (ISRCTN18181860) 27 including the same baseline questionnaire and serological testing was administered in the Swiss general population and in several subpopulations. 28 For this study, we used data from Corona Immunitas phase 2 of the canton of Zurich, for which randomly selected individuals from the general population were recruited using age strati ed sampling (20-64 years, ≥65 years) and invited to participate. ...
Background:
The social distancing measures associated with the COVID-19 pandemic had far reaching effects on sexual behavior worldwide. However, it remains unclear whether sexual contact with non-steady partners was a contributor to the spread of SARS-CoV-2. The aim of this study was to (i) assess whether the SARS-CoV-2 seropositivity after the first pandemic wave among people using HIV Pre-Exposure Prophylaxis (PrEP) in Zurich, Switzerland differed from that of a demographic matched population level comparison group, (ii) describe risk factors for SARS-CoV-2 seropositivity in this population, and (iii) determine whether sexual contact with non-steady partners was associated with SARS-CoV-2 seropositivity.
Methods:
The study was conducted between July 2020 and October 2020 as a nested cross-sectional study within two ongoing cohort studies, SwissPrEPared (all eligible PrEP users in Switzerland ≥18 years old) and Corona Immunitas (a series of cross-sectional and longitudinal studies measuring the SARS-CoV-2 seroprevalence across Switzerland, beginning in April 2020). All SwissPrEPared participants were recruited from Checkpoint Zurich (the main PrEP clinic in Zurich). Data were collected on participants’ SARS-CoV-2 antibody status, social characteristics and behavioral data after the first wave of the corona pandemic in Switzerland, and seroprevalence was compared with a propensity score-matched sample from the general Zurich population.
Results:
Of the 218 participants enrolled, 8.7% (n=19, 95% CI: 5.5-13.5%) were seropositive for SARS-CoV-2 during the first pandemic wave, higher than that of the general male population in Zurich aged 20-65 (5.5%, 95% CI: 3.8–8.2%). Participants on average reduced their social outings, but the seronegative were more socially active before, during, and after the first lockdown period. In a logistic model, increasing mean sexual partner count was not associated with seropositivity (OR: 0.9, 95% CI: 0.8, 1.0), but increasing number of trips abroad was associated with higher seropositivity (p=0.06, OR: 1.14, 95% CI: 1.0, 1.3). The estimated risk ratio for seropositivity for the participants compared to the general Zurich population after propensity score matching was 1.5 (95% CI: 0.53, 4.0). 94% of participants reported later receiving a COVID-19 vaccination.
Discussion:
Our study suggests that COVID-19 seropositivity was slightly elevated among people taking PrEP in Zurich during the first wave of the pandemic, but that socializing and sexual activity were less important than other factors in contributing to risk.
... In accordance with national guidelines and scientific evidence, a previous infection that occurred at least 90 days prior to the current one was considered a new positive and was ranked within the immunization groups as equivalent to a single dose of vaccination. Therefore, the presence of a previous infection along with one or two doses of vaccine constitutes the completion of the primary series or booster vaccination [14][15][16]. ...
Objective: To investigate the effectiveness of SARS-CoV2 vaccination in preventing ordinary or intensive care unit (ICU) admissions and deaths among cases registered during a variant transitional pandemic phase in the geographically and culturally unique territory of the Province of Bolzano (South Tyrol), an Italian region with low vaccination coverage.
Methods: We collected data from 93,643 patients registered as positive for SARS-CoV-2 by health authorities during the winter of 2021–22. The data were analyzed retrospectively using descriptive statistics and multiple logistic regression.
Results: 925 patients were hospitalized (0.99%), 89 (0.10%) were in intensive care, and 194 (0.21%) died. Vaccinated patients had a significantly lower risk of being hospitalized: adjusted Odds Ratio (aOR): 0.39; 95% CI: 0.33–0.46, ICU admission: aOR: 0.16; 95% CI: 0.09–0.29 and death: aOR: 0.41; 95% CI: 0.29–0.58. Similar risk reductions were also observed in booster-vaccinated patients, independent of sex, age, and predominant variant. Furthermore, the median length of stay (LoS) in the ICU was significantly longer for unvaccinated individuals compared to vaccinated subjects (9 vs. 6 days; p < 0.003).
Conclusion: Primary series vaccination and ongoing campaign booster doses were effective in preventing all severe disease-related outcomes and in reducing ICU Length of Stay, even during a transitional pandemic phase and in a unique territorial context.
... This observation was consistent across age groups. Most studies [35][36][37][38][39][40] found that individuals with hybrid immunity had the highest anti-spike IgG titres and neutralising responses followed by vaccinated and then infected individuals, but most of these studies focussed on adults. A study by Zaballa et al. 7 , found that neutralising activity, especially for Omicron BA.1 and even more so for subsequent subvariants (Omicron BA.2, BA.2.12.1, BA.4/BA.5), ...
Understanding the development of humoral immune responses of children and adolescents to SARS-CoV-2 is essential for designing effective public health measures. Here we examine the changes of humoral immune response in school-aged children and adolescents during the COVID-19 pandemic (June 2020 to July 2022), with a specific interest in the Omicron variant (beginning of 2022). In our study “Ciao Corona”, we assess in each of the five testing rounds between 1874 and 2500 children and adolescents from 55 schools in the canton of Zurich with a particular focus on a longitudinal cohort (n=751). By July 2022, 96.9% (95% credible interval 95.3–98.1%) of children and adolescents have SARS-CoV-2 anti-spike IgG (S-IgG) antibodies. Those with hybrid immunity or vaccination have higher S-IgG titres and stronger neutralising responses against Wildtype, Delta and Omicron BA.1 variants compared to those infected but unvaccinated. S-IgG persist over 18 months in 93% of children and adolescents. During the study period one adolescent was hospitalised for less than 24 hours possibly related to an acute SARS-CoV-2 infection. These findings show that the Omicron wave and the rollout of vaccines boosted S-IgG titres and neutralising capacity. Trial registration number: NCT04448717. https://clinicaltrials.gov/ct2/show/NCT04448717.
... Other studies have reported results that are in line with ORCHESTRA. For example, in one cohort study conducted in Switzerland after the emergence of Omicron [26], individuals with natural immunity had 15 times lower antibody titers than vaccinated people, and less than half of them showed neutralization activity. In another cohort study enrolling HCWs [27], triple vaccination and double vaccination with prior or subsequent infection showed the highest neutralization response. ...
ORCHESTRA (“Connecting European Cohorts to Increase Common and Effective Response To SARS-CoV-2 Pandemic”) is an EU-funded project which aims to help rapidly advance the knowledge related to the prevention of the SARS-CoV-2 infection and the management of COVID-19 and its long-term sequelae. Here, we describe the early results of this project, focusing on the strengths of multiple, international, historical and prospective cohort studies and highlighting those results which are of potential relevance for vaccination strategies, such as the necessity of a vaccine booster dose after a primary vaccination course in hematologic cancer patients and in solid organ transplant recipients to elicit a higher antibody titer, and the protective effect of vaccination on severe COVID-19 clinical manifestation and on the emergence of post-COVID-19 conditions. Valuable data regarding epidemiological variations, risk factors of SARS-CoV-2 infection and its sequelae, and vaccination efficacy in different subpopulations can support further defining public health vaccination policies.
We investigate the impact of differential vaccine effectiveness, waning immunity, and natural cross-immunity on the capacity for vaccine-induced strain replacement in two-strain models of infectious disease spread. We focus specifically on the case where the first strain is more transmissible but the second strain is more immune-resistant. We consider two cases on vaccine-induced immunity: (1) a monovalent model where the second strain has immune escape with respect to vaccination; and (2) a bivalent model where the vaccine remains equally effective against both strains. Our analysis reaffirms the capacity for vaccine-induced strain replacement under a variety of circumstances; surprisingly, however, we find that which strain is preferred depends sensitively on the degree of differential vaccine effectiveness. In general, the monovalent model favors the more immune-resistant strain at high vaccination levels while the bivalent model favors the more transmissible strain at high vaccination levels. To further investigate this phenomenon, we parametrize the bifurcation space between the monovalent and bivalent model.
The literature associating the spread of SARS-CoV-2 with the healthcare-related, geographical, and demographic characteristics of the territory is inconclusive and contrasting. We studied these relationships during winter 2021/2022 in South Tyrol, a multicultural Italian alpine province, performing an ecological study based on the 20 districts of the area. Data about incidence, hospitalization, and death between November 2021 and February 2022 were collected and associated to territorial variables via bivariate analyses and multivariate regressions. Both exposure variables and outcomes varied widely among districts. Incidence was found to be mainly predicted by vaccination coverage (negative correlation). Mortality and ICU admission rates partially followed this distribution, while the case fatality rate was inversely correlated to average salary, and hospital admission rates increased where hospitals capacity was higher, and from the southern to the northern border of the province. These findings, besides confirming the efficacy of vaccination in preventing both new and severe SARS-CoV-2 cases, highlight that several geographical and socio-demographic variables can be related to disease epidemiology. Remote areas with wage gaps and lower access to care suffered most from the pandemic. Our findings, therefore, underly the existence of health inequity issues that need to be targeted by implementing specifically tailored public health interventions.
Background
The social distancing measures associated with the COVID-19 pandemic had far reaching effects on sexual behavior worldwide. However, it remains unclear whether sexual contact with non-steady partners was a contributor to the spread of SARS-CoV-2. The aim of this study was to (i) describe risk factors for SARS-CoV-2 seropositivity after the first pandemic wave among people using HIV Pre-Exposure Prophylaxis (PrEP) in Zurich, Switzerland, including sexual contact with non-steady partners, and (ii) assess whether the SARS-CoV-2 seropositivity among PrEP users in this time period differed from that of a demographic matched population level comparison group.
Methods
The study was conducted between July 2020 and October 2020 as a nested cross-sectional study within two ongoing cohort studies, SwissPrEPared (all eligible PrEP users in Switzerland ≥ 18 years old) and Corona Immunitas (a series of cross-sectional and longitudinal studies measuring the SARS-CoV-2 seroprevalence across Switzerland, beginning in April 2020). All SwissPrEPared participants were recruited from Checkpoint Zurich (the main PrEP clinic in Zurich) and were men having sex with men or transgender women. Data were collected on participants’ SARS-CoV-2 antibody status, social characteristics and behavioral data after the first wave of the pandemic in Switzerland, and seroprevalence was compared with a propensity score-matched sample from the general Zurich population.
Results
Of the 218 participants enrolled, 8.7% (n = 19, 95% CI: 5.5–13.5%) were seropositive for SARS-CoV-2 during the first pandemic wave, higher than that of the general male population in Zurich aged 20–65 (5.5%, 95% CI: 3.8–8.2%). Participants on average reduced their social outings, but the seronegative were more socially active before, during, and after the first lockdown period. In a logistic model, increasing mean sexual partner count was not associated with seropositivity (OR: 1.02, 95% CI: 0.95, 1.07). The estimated risk ratio for seropositivity for the participants compared to the general Zurich population after propensity score matching was 1.46 (95% CI: 0.53, 3.99).
Conclusions
Our study suggests that SARS-CoV-2 seropositivity was slightly elevated among people taking PrEP in Zurich during the first wave of the pandemic, but that socializing and sexual activity were less important than other factors in contributing to risk.
In Canada’s federated healthcare system, 13 provincial and territorial jurisdictions have independent responsibility to collect data to inform health policies. During the COVID-19 pandemic (2020–2023), national and regional sero-surveys mostly drew upon existing infrastructure to quickly test specimens and collect data but required cross-jurisdiction coordination and communication.
There were 4 national and 7 regional general population SARS-CoV-2 sero-surveys. Survey methodologies varied by participant selection approaches, assay choices, and reporting structures. We analyzed Canadian pandemic sero-surveillance initiatives to identify key learnings to inform future pandemic planning.
Over a million samples were tested for SARS-CoV-2 antibodies from 2020 to 2023 but siloed in 11 distinct datasets. Most national sero-surveys had insufficient sample size to estimate regional prevalence; differences in methodology hampered cross-regional comparisons of regional sero-surveys. Only four sero-surveys included questionnaires. Sero-surveys were not directly comparable due to different assays, sampling methodologies, and time-frames. Linkage to health records occurred in three provinces only. Dried blood spots permitted sample collection in remote populations and during stay-at-home orders.
To provide timely, high-quality information for public health decision-making, routine sero-surveillance systems must be adaptable, flexible, and scalable. National capability planning should include consortiums for assay design and validation, defined mechanisms to improve test capacity, base documents for data linkage and material transfer across jurisdictions, and mechanisms for real-time communication of data. Lessons learned will inform incorporation of a robust sero-survey program into routine surveillance with strategic sampling and capacity to adapt and scale rapidly as a part of a comprehensive national pandemic response plan.
