As Covid-19 cases rise worldwide, experts are facing the critical question about catching the disease a second time. Research done by a team of scientists from CSIR- IGIB (Institute of Genomics and Integrative Biology) has found reinfection cases in a few parts of the country. The people who tested positive are healthcare workers at the Government Institute of Medical Sciences, Greater Noida.
Their infections were picked up as part of the routine check-up that the hospital conducts on its staff.
IGIB director Dr Arun Agarwal tells The Daily Guardian that more cases of reinfection are expected in the coming days.
Q. What is reinfection?
A. Reinfection is when a person infected by a pathogen (here, SARS- CoV2 virus) clears the infection completely, such that the pathogen is eliminated, but subsequently gets infected again by the same pathogen.
Q. How can one establish reinfection?
A. To establish reinfection, one should clearly show a first infection, a phase of clearance, and a second infection that is clearly different from the first infection. For Covid-19, this is best described as certain infection with RT-PCR positive both times, clear separation from first infection with a negative RT-PCR and/or a positive antibody test, with virus genome sequencing of both the first and second infections being clearly different and unlikely to represent mutation or editing within the host. Also, the clinical picture and technical testing data should be looked at to ensure high confidence in the diagnosis of an infection. This is most certain when the infections are symptomatic with a clinical diagnosis of Covid-19 and less certain when they are asymptomatic.
Q. What does the research done by IGIB say about reinfection?
A. IGIB has worked on suspected reinfection cases sent by clinical partners. IGIB scientists sequence the SARS CoV2 RNA from each episode and look for similarities and differences. We have, by now, seen multiple cases from clinical partners, first from Mumbai and now from Delhi, where the virus is sufficiently different between the first and second episodes to call it a likely reinfection.
Q. Have you seen a mutation of the virus in reinfection cases?
A. By the definition above, we only call it reinfection when the virus is sufficiently different. If the mutations occurred within the host, it would be a reactivation, not reinfection. This is possible in some cases.
Q. Are you doing this research on Covid-19 symptomatic cases too?
A. We are looking for symptomatic cases to see if there are more or less severe symptoms during re0infection. Either is possible at this time but we are hoping for milder cases during reinfection.
