Suspected SARS-Cov-2 reinfections in health care workers from Assam, India: Are they true reinfections?

Abstract

Frontline healthcare workers (HCWs) are repeatedly exposed to SARS-CoV-2 and chance of exposure to it are invariably high than any other category of population. In this study, we investigated suspected cases of SARS-CoV-2 reinfection among eight HCWs involved in COVID-19 healthcare duty in Dibrugarh, Assam. Diagnosis of SARS-CoV-2 was done by Real Time RT-PCR or Rapid Antigen Detection Test at AMCH, Dibrugarh and ICMR-RMRC, Dibrugarh. Cases who tested positive for SARS-CoV-2 by RT-PCR or RAT for the second time and with symptoms suggestive of COVID-19 were included in this investigation as\nsuspected cases of reinfection. SARS-CoV-2 IgG Ab titre and immune status ratio was estimated using a commercial SARS-CoV-2 Ig Ab detection ELISA kit. All eight cases were asymptomatic in first episode of infection with a CT value above 30 and were non-reactive for SARS-CoV-2 IgG Ab. The second episode was symptomatic and marginally severe in some cases with CT value less than 30 and with positive SARS-CoV-2 Ab titre. Most asymptomatic cases with CT value above 30 failed to elicit immune response during the first episode. This may suggest that SARS-CoV-2 in low amount might be harbored transiently as bystander in droplet particles before being expelled from the nasal cavity which can be detected by the highly sensitive Real Time RT-PCR test. They may be below the infectious dose that is necessary to cause a clinical or a sub-clinical infection and fails to illicit an immune response. It is therefore very important to critically analyze the suspected cases of reinfection to be labelled as true reinfections. In conclusion, not all resurgence of symptoms with positive SARS-Cov-2 result for the second time after recovery are true reinfections and may be labelled as retest positives rather than reinfections. Further, routine surveillance of SARS-Cov-2 Ab testing for HCW is recommended to ascertain their immune status as they are the frontline workers of managing COVID-19 patients and a