The Longitudinal Analysis on the Anti-SARS-CoV-2 Antibodies among Healthcare Workers in Poland—Before and after BNT126b2 mRNA COVID-19 Vaccination

Abstract

One of the groups most vulnerable to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is healthcare workers (HCWs) who have direct contact with suspected and confirmed coronavirus diseases 2019 (COVID-19) patients. Therefore, this study aimed to (i) conduct a longitudinal analysis of the seroprevalence of SARS-CoV-2 infection among HCWs working in two healthcare units (HCUs) in Poland and (ii) identify anti-SARS-CoV-2 IgG antibody (Ab) response factors following infection and anti-COVID-19 vaccination. The overall seroprevalence increased from 0% at baseline in September 2020 to 37.8% in December 2020. It reached 100% in February 2021 after BNT126b2 (Pfizer New York, NY, USA/BioNTech Mainz, Germany) full vaccination and declined to 94.3% in September 2021. We observed significant differences in seroprevalence between the tested high- and low-risk infection HCUs, with the highest seropositivity among the midwives and nurses at the Gynecology and Obstetrics Ward, who usually have contact with non-infectious patients and may not have the proper training, practice and personal protective equipment to deal with pandemic infections, such as SARS-CoV-2. We also found that anti-SARS-CoV-2 Ab levels after coronavirus infection were correlated with disease outcomes. The lowest Ab levels were found among HCWs with asymptomatic coronavirus infections, and the highest were found among HCWs with severe COVID-19. Similarly, antibody response after vaccination depended on previous SARS-CoV-2 infection and its course: the highest anti-SARS-CoV-2 Ab levels were found in vaccinated HCWs after severe COVID-19. Finally, we observed an approximately 90–95% decrease in anti-SARS-CoV-2 Ab levels within seven months after vaccination. Our findings show that HCWs have the highest risk of SARS-CoV-2 infection, and due to antibody depletion, extra protective measures should be undertaken. In addition, in the context of the emergence of new pathogens with pandemic potential, our results highlight the necessity for better infectious disease training and regular updates for the low infection risk HCUs, where the HCWs have only occasional contact with infectious patients.

Differences in BNT126b2 and ChAdOx1 Homologous Vaccination Antibody Response among Teachers in Poznan, Poland

“…However, due to their medical background, the lecturers involved in our study were also involved in fighting the pandemic, e.g., in molecular diagnostics of SARS-CoV-2 infection. Our previous study showed that HCWs are at the highest risk of SARS-CoV-2 infection and are characterised by the highest seroprevalence among the occupational groups [ 45 ]. Further, other authors have demonstrated the clinical work environment as a key SARS-CoV-2 infection risk factor [ 46 , 47 ] but have also highlighted that local COVID-19 foci and household contacts may affect seropositivity rates [ 47 , 48 ].…”

Anti-SARS-CoV-2 Antibodies Level and COVID-19 Vaccine Boosters among Healthcare Workers with the Highest SARS-CoV-2 Infection Risk—Follow Up Study

“…Post-vaccination antibodies were found in 68 of the 69 analysed HCWs, and the prevalence of anti-SARS-CoV-2 S antibodies increased from 84.50% in September 2021 [12] to 98.56% in November 2022. Among these HCWs, there was one individual with a complete depletion of anti-SARS-CoV-2 S antibodies.…”

“…Seven individuals had developed anti-SARS-CoV-2 NCP antibodies without declaring COVID-19 in their history. The prevalence of anti-SARS-CoV-2 NCP antibodies increased from 5.71% in September 2021 [12] to 39.1% in November 2022.…”

“…The study group included 69 HCWs (Table 1), of whom the vast majority took part in our previous study on the anti-SARS-CoV-2 antibody level [12]. Most participants were women (84.06%) and were aged 41.44 ± 13.71 years.…”

“…In our previous study [12], we assessed anti-SARS-CoV-2 S Ab levels after completion of a mandatory COVID-19 primary vaccination series among HCWs in February 2021. Within seven months of vaccination we observed that the Ab level decreased by approximately 90-95%; however, none of the HCWs contracted COVID-19.…”