Longitudinal humoral and cell-mediated immune responses in a population-based cohort in Zurich, Switzerland between March and June 2022 - evidence for protection against Omicron SARS-CoV-2 infection by neutralizing antibodies and spike-specific T-cell responses.

OBJECTIVES: The correlate(s) of protection against SARS-CoV-2 remain incompletely defined. Additional information regarding the combinations of antibody and T cell-mediated immunity which can protect against (re)infection is needed. METHODS: We conducted a population-based, longitudinal cohort study including 1044 individuals of varying SARS-CoV-2 vaccination and infection statuses. We assessed spike (S)- and nucleocapsid (N)-immunoglobulin(Ig)G and wildtype, Delta, and Omicron-neutralizing antibody (N-Ab) activity. In a subset of 328 individuals, we evaluated S, membrane (M), and N-specific T cells. Three months later, we reassessed Ab (n = 964) and T cell (n = 141) responses and evaluated factors associated with protection from (re)infection. RESULTS: At the study start, >98% of participants were S-IgG seropositive. N-IgG and M/N-T-cell responses increased over time, indicating viral (re)exposure, despite existing S-IgG. Compared to N-IgG, M/N-T cells were a more sensitive measure of viral exposure. High N-IgG titers, Omicron-N-Ab activity, and S-specific-T-cell responses were all associated with a reduced likelihood of (re)infection over time. CONCLUSION: Population-level SARS-CoV-2 immunity is S-IgG-dominated, but heterogeneous. M/N-T-cell responses can distinguish previous infection from vaccination, and monitoring a combination of N-IgG, Omicron-N-Ab, and S-T-cell responses may help estimate protection against SARS-CoV-2 (re)infection.

Productivity losses due to influenza and influenza-like illness in Switzerland: results of the Swiss Sentinel Surveillance Network in a non-pandemic era.

BACKGROUND: The incidence of influenza and influenza-like illnesses in Switzerland is generally high. Although related direct medical costs can be substantial, especially if hospitalisations occur, several studies suggested that indirect costs due to the loss of productivity may represent an even higher economic burden. The aim of this study was to assess the costs arising from lost productivity due to influenza and influenza-like illnesses in Switzerland. METHODS: Analyses were based on data collected in 2016 and 2017 by the Swiss Sentinel Surveillance Network of the Swiss Federal Office of Public Health (SFOPH). The available information covered details on the physicians collecting the data, patients' characteristics, symptoms, treatments, and inability to work (in terms of physician-recorded workdays lost for own sickness or caregiving). The cost of lost productivity, estimated using the human capital approach, was calculated as the number of workdays lost due to influenza-like illnesses multiplied by the mean salary for one working day. Salary differences across sex, age and region were considered. Extrapolation to the national level was performed by adjusting for the size of the Swiss population, the age and sex distribution, the regional distribution, the number of Sentinel general physician contacts and the specialisation of the physician. RESULTS: At the Swiss national level, the estimated total yearly number of cases of inability to work due to influenza and influenza-like illnesses was 101,287 in 2016 and 86,373 in 2017. In subgroups defined by year, gender, region and age class, numbers of cases per 100,000 inhabitants ranged from 12 to 2396. The total number of workdays lost in Switzerland, considering degree of employment and visit day, were estimated to be 324,118 in 2016 and 278,121 in 2017. The number of workdays lost was generally higher in men (53.7% of the total in 2016 and 55.6% of the total in 2017) than women. The estimated total costs due to inability to work, calculated using a human capital approach and including the caregiving costs, were CHF 115 million in 2016 and CHF 103 million in 2017, equivalent to CHF 1.4 million per 100,000 inhabitants. CONCLUSION: The costs of lost productivity due to influenza and influenza-like illnesses in Switzerland are substantial and may vary considerably between different years, regions and age classes. As the present analyses could not consider all causes of lost productivity (e.g., short-term inability to work not requiring a physician consultation, hospitalisations, early retirement, premature death), the total indirect costs due to influenza or influenza-like illnesses can be expected to be higher than the presented estimates.

Immunogenicity and safety of the tick-borne encephalitis vaccination (2009-2019): A systematic review.

BACKGROUND: Tick-borne encephalitis (TBE) is increasing in Europe. We aimed to evaluate the immunogenicity and safety of TBE-vaccination. METHODS: This systematic review was registered at PROSPERO (#CRD42020155737) and conducted in accordance with PRISMA guidelines. We searched CINAHL, Cochrane, Embase, PubMed, and Scopus using specific terms. Original articles, case reports and research abstracts in English, French, German and Italian were included for screening and extracting (JER; PS). RESULTS: Of a total of 2464 records, 49 original research publications were evaluated for immunogenicity and safety. TBE-vaccines showed adequate immunogenicity, good safety and interchangeability in adults and children with some differences in long-term protection (Seropositivity in 90.6-100% after primary vaccination; 84.9%-99.4% at 5 year follow up). Primary conventional vaccination schedule (days 0, 28, and 300) demonstrated the best immunogenic results (99-100% of seropositivity). Mixed brand primary vaccination presented adequate safety and immunogenicity with some exceptions. After booster follow-ups, accelerated conventional and rapid vaccination schedules were shown to be comparable in terms of immunogenicity and safety. First booster vaccinations five years after primary vaccination were protective in adults aged <50 years, leading to protective antibody levels from at least 5 years up to 10 years after booster vaccination. In older vaccinees, > 50 years, lower protective antibody titers were found. Allergic individuals showed an adequate response and immunosuppressed individuals a diminished response to TBE-vaccination. CONCLUSIONS: The TBE-vaccination is generally safe with rare serious adverse events. Schedules should, if possible, use the same vaccine brand (non-mixed). TBE-vaccines are immunogenic in terms of antibody response but less so when vaccination is started after the age of 50 years. Age at priming is a key factor in the duration of protection.