SARS-CoV-2 Seroprevalence among Health Care Workers-A Voluntary Screening Study in a Regional Medical Center in Southern Germany

[SARS-CoV-2 Exposure and Seroprevalence of SARS-CoV-2 Antibodies among Medical Students in the First Phase of the Pandemic 2020-2021]

BACKGROUND

Due to their clinical training and secondary activities in the hospital, medical students are exposed to contact with SARS-CoV-2 infected people more often than the general population. We determined the seroprevalence of SARS-CoV-2 antibodies in medical students in clinical training at different times during the pandemic and asked participants about possible SARS-CoV-2 exposures in both medical and private settings.

METHODS

From May 2020 to June 2021, medical students each in their 3rd year of training at the University Hospital Würzburg participated in the cross-sectional survey. All SARS-CoV-2 unvaccinated students were offered a determination of their SARS-CoV-2 serostatus. The blood samples were tested by an immunoassay (Elecsys, Roche) for IgG/IgM/IgA antibodies against the SARS-CoV-2 N antigen. Demographic data, SARS-CoV-2 disease and vaccination status, as well as possible SARS-CoV-2 exposures were collected using a questionnaire.

RESULTS

Overall, 383 (86.1%) of 445 students took part in the cross-sectional survey (65% female; median age 22 years; IQR 21-24). Serostatus was determined in 223 (58.2% of 383) SARS-CoV-2 unvaccinated participants. In the period between the beginning of the pandemic in Germany (February 2020) and the time of the survey, 332 (86.7% of 383) students stated that they worked in the medical field, mainly in the context of clinical traineeships (76.8%) or secondary activities with patient contact (48.8%); 129 (33.7%) reported previous contact with a COVID-19 patient, of which 78.3% of contacts took place at a medical facility. Antibodies against SARS-CoV-2 were detected in 8 (3.6%) of the 223 unvaccinated participants tested, and in 3 infected persons an association between infection and contact in the course of medical activity seemed likely.

CONCLUSION

Despite frequent patient contact and the associated increased risk of infection, medical students in their 3rd year of training did not show an increased seroprevalence compared to the general population and showed a lower or similar seroprevalence rate than medical students in other European countries in the first 18 months of the pandemic. This indicates sufficient protection of medical students at the beginning of clinical training through the hygiene and infection protection measures implemented at that time during medical activities.

Seroprevalence of SARS-CoV-2 Antibodies in Employees of Three Hospitals of a Secondary Care Hospital Network in Germany and an Associated Fire Brigade: Results of a Repeated Cross-Sectional Surveillance Study Over 1 Year

Healthcare workers (HCWs) are playing a vital role in the current SARS-CoV-2 pandemic. This study investigated how infection spreads within three local hospitals and an associated fire brigade in Germany by testing employees for the presence of SARS-CoV-2 IgG antibodies over one year. The three observational periods corresponded to the initial three pandemic waves: first wave: June-September 2020, second wave: October 2020-January 2021, and third wave: February-June 2021. We analysed 3285 serum samples of 1842 employees, which represents 65.7% of all employees. Altogether, 13.2% employees were seropositive: 194/1411 HCWs (13.7%) and 49/431 non-HCWs (11.4%) with a clear increase of seroprevalence from the first (1.1%) to the second (13.2%) and third (29.3%) pandemic wave. HCWs presumably had an additional occupational risk for infection in the second and third wave due to an increase of infection pressure with more COVID-19 patients treated, showing possible weak points in the recommended infection prevention strategy.

Longitudinal SARS-CoV-2 seroepidemiological investigation among healthcare workers at a tertiary care hospital in Germany

Background

SARS-CoV-2 cases in Germany increased in early March 2020. By April 2020, cases among health care workers (HCW) were detected across departments at a tertiary care hospital in Berlin, prompting a longitudinal investigation to assess HCW SARS-CoV-2 serostatus with an improved testing strategy and associated risk factors.

Methods

In May/June and December 2020, HCWs voluntarily provided blood for serology and nasopharyngeal/oropharyngeal (NP/OP) samples for real-time polymerase chain reaction (PCR) and completed a questionnaire. A four-tiered SARS-CoV-2 serological testing strategy including two different enzyme-linked immunosorbent assays (ELISA) and biological neutralization test (NT) was used. ELISA-NT correlation was assessed using Pearson’s correlation coefficient. Sociodemographic and occupational factors associated with seropositivity were assessed with multivariate logistic regression.

Results

In May/June, 18/1477 (1.2%) HCWs were SARS-CoV-2 seropositive, followed by 56/1223 (4.6%) in December. Among those tested in both, all seropositive in May/June remained seropositive by ELISA and positive by NT after 6 months. ELISA ratios correlated well with NT titres in May/June (R = 0.79) but less so in December (R = 0.41). Those seropositive reporting a past SARS-CoV-2 positive PCR result increased from 44.4% in May/June to 85.7% in December. HCWs with higher occupational risk (based on profession and working site), nurses, males, and those self-reporting COVID-19-like symptoms had significantly higher odds of seropositivity.

Conclusions

This investigation provides insight into the burden of HCW infection in this local outbreak context and the antibody dynamics over time with an improved robust testing strategy. It also highlights the continued need for effective infection control measures particularly among HCWs with higher occupational risk.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07057-3.

Seroprevalence of SARS-CoV-2 and Risk Assessment Among Healthcare Workers at a Dedicated Tertiary Care COVID-19 Hospital in Delhi, India: A Cohort Study

Background

Healthcare workers (HCWs) have a substantially higher risk of Covid-19 infection but there is a paucity of information on the risk factors of disease transmission in high-burden real-world settings.

The study objective was to determine the seroprevalence of SARS-CoV-2 among healthcare workers in a high-burden Covid-19 setting and to estimate the incidence and identify the risk factors of infection.

Methods

This was a prospective observational cohort study amongst doctors and nurses working at a dedicated Covid-19 tertiary care government hospital in Delhi, India. A baseline blood sample (2-3ml) was collected from all the participants to test for the presence of total SARS-CoV-2 antibodies. The HCWs that were seronegative (non-reactive) at baseline were followed-up for ≥21≤28 days with the collection of a second blood sample to assess for the incidence of SARS-CoV-2 infection.

Results

A total of 321 (51.3%, 95% C.I 47.4, 55.3) HCWs were detected with SARS-CoV-2 antibodies on baseline examination. The seroprevalence, when adjusted for assay characteristics, was 54.5% (95% C.I 50.3, 58.6). On bivariate analysis, SARS-CoV-2 antibody positivity lacked statistically significant association with either age, sex, occupation, cumulative duty duration, and smoking status. The incidence of seroconversion in the baseline seronegative cohort on follow-up after 21-28 days was observed in 35 (14.9%) HCWs (n=245). Furthermore, the self-reported adherence to infection prevention and control measures did not show a statistically significant association with antibody positivity in the HCWs, neither at baseline nor on follow-up.

Conclusions 

The high risk of SARS-CoV-2 transmission in HCWs may be substantially reduced by adherence to Infection Prevention Control (IPC) and protective measures. 

Assessment of SARS-CoV-2 Infection among Healthcare Workers of a German COVID-19 Treatment Center

To date, more than 160 million people have been infected with COVID-19 worldwide. In the present study, we investigated the history of SARS-CoV-2 infection among 3067 healthcare workers (HCW) in a German COVID-19 treatment center during the early phase of the pandemic (July 2020) based on the seroprevalence of SARS-CoV-2 antibodies and self-reported previous PCR results. The results demonstrate a low prevalence of SARS-CoV-2 infection (n = 107 [3.5%]) with no increased risk for employees with a high level of patient exposure in general or working in COVID-19-confined areas in particular. This suggests that the local hygiene standards implemented in our hospital during the first wave of COVID-19 pandemic were effective in preventing patient-to-HCW transmission. No evidence for highly mobile staff serving as a vector for SARS-CoV-2 transmission could be found. In addition, impairment of smell and/or taste was strongly associated with SARS-CoV-2 history.