Incidence of SARS-CoV-2 re-infection in anti-nucleocapsid IgG-positive healthcare workers: a prospective cohort study.

BACKGROUND : Since the pandemic of SARS-CoV-2 began, our understanding of the pathogenesis and immune responses to this virus has continued to evolve. It has been shown that this infection produces natural detectable immune responses in many cases. However, the duration and durability of immunity and its effect on the severity of the illness are still under investigation. Moreover, the protective effects of antibodies against new SARS-CoV-2 variants still remain unclear. OBJECTIVES: To assess the incidence and associated demographic features of SARS-CoV-2 infection in anti-nucleocapsid IgG-positive and anti-nucleocapsid IgG-negative healthcare workers. MATERIAL AND METHODS: This prospective longitudinal cohort study was conducted in Peshawar Medical College group of hospitals of Prime Foundation. Anti-nucleocapsid IgG sero-positive and anti-nucleocapsid IgG sero-negative healthcare workers were followed for a period of 6 months (from 1 Aug 2020 to 31 Jan 2021), and the incidence of SARS-CoV-2 was confirmed by RT-PCR. RESULTS: A total number of 555 cohorts were followed for a period of 6 months; of them 365 (65.7%) were anti-nucleocapsid-negative (group A) and 190 (34.3%) were anti-nucleocapsid-positive (group B) healthcare workers. The mean age of the study cohort was 33.85 ± 9.80 (anti-N (-), 34.2 ± 10.58; anti-N ( +), 33.5 ± 9.50). The median antibody level in anti-nucleocapsid-positive HCWs was 15.95 (IQR: 5.24-53.4). Male gender was the majority in both groups (group A, 246 (67%), group B, 143 (48%)) with statistically significant difference (P < 0.05). Majority of the HCWs were blood group B in both groups (34% each). None of the 190 anti-nucleocapsid-positive HCWs developed subsequent SARS-CoV-2 re-infection, while 17% (n = 65) HCWs developed infection in anti-nucleocapsid-negative group during the 6-month follow-up period. CONCLUSION: In conclusion, none of the anti-nucleocapsid-positive HCWs developed SARS-CoV-2 re-infection in this study, and the presence of IgG anti-nucleocapsid antibodies substantially reduce the risk of re-infection for a period of 6 months.

Identifying higher risk subgroups of health care workers for priority vaccination against COVID-19.

Background: Health care workers (HCWs) are exposed to high risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection due to close contact with infected patients in hospital. The objective of this study was to estimate the seroprevalence and to identify the exposure risk of various subgroups among HCWs to prioritize them for early vaccination. Methods: This was a multicentre cross-sectional study conducted between 15 and 29 June 2020. A total of 987 HCWs were recruited randomly from two major tertiary-care hospitals of Peshawar city, Pakistan. The HCWs included doctors, nurses, paramedics and hospital support staff. The US Food and Drug Administration (FDA)-approved kit was used for the detection of SARS-CoV-2 antibodies. Results: Overall, 310 (31.4%) HCWs were seropositive for SARS-CoV-2 antibodies (95% confidence interval, CI: 28.5-34.4). Seroprevalence was higher in males (33.5%) and in age group 51-60 years (40.9%). Seropositivity increased with increasing age from 8.3% in age group ⩽20 to 40.9% in 51-60 years of age group (p < 0.05). The highest seroprevalence was identified in paramedical staff (42·5%, 95% CI: 36.6-48.6) followed by nursing staff (38·8%, 95% CI: 32.1-45.7). In logistic regression, being a male HCW led to higher risk of seropositivity (odds ratio, OR: 1.50, 95% CI: 1·06-2.13. p < 0.05) compared with female staff members. The odds of seropositivity was higher in nurses (OR: 3·47, 95% CI: 1.99-6.05. p < 0.01), paramedical staff (OR: 3·19, 95% CI: 1.93-5.28. p < 0.01) and hospital support staff (OR: 2·47, 95% CI: 1.29-4.7. p < 0.01) compared with consultants. Conclusion: Overall, our results concluded that nursing and paramedical staff are at higher risk and should be vaccinated on priority.