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

Abstract

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. Supplementary information The online version contains supplementary material available at 10.1007/s11845-022-02997-w.

A Consideration of the Relationship in COVID-19 Infection Status and Previously Reported Anti-SARS-CoV-2 Nucleocapsid (N)

“…In a study of healthcare workers positive for anti-N antibodies, it was reported that anti-N antibodies greatly reduced the risk of re-infection for 6 months. 7 Another study reported that anti-N antibodies in COVID-19 convalescent patients persisted for over a year, with an increased response rate in the first 25-30 weeks, and that they subsequently began to decrease and remained detectable for >15 months. 8 The anti-N antibody situation in Japan suggests that the infection may spread for some time.…”