For calling it a reinfection a person with Covid-19 must have two positive tests at an interval of at least 102 days with one interim negative test said the ICMR study.
It further stated that a confirmation of the re-infection will require a whole-genome sequencing.
According to the study SARS-CoV-2 re-infection: development of an epidemiological definition from India; which has been published by Cambridge in the Epidemiology and Infection journal showed that an investigation was concluded with the objective to develop an epidemiological case definition of possible SARS CoV-2 re-infection and assess its magnitude in India.
While it is still a rare phenomenon to have coronavirus re-infection but the Indian scientists have developed an easy-to-use epidemiological definition of re-infection for establishing surveillance systems.
The scientists highlighted, SARS-CoV-2 re-infection is a concern and there is a need to define it. Therefore, according to a telephonic survey working epidemiological case definition for re-infection was developed and its magnitude was explored through archive-based.
Cambridge @Epidemio_Infect publishes ICMR study on definition of SARS-CoV-2 re-infection. Research article is accessible at https://t.co/hfjOSdNRL2@MoHFW_INDIA @drharshvardhan @AshwiniKChoubey @PIB_India pic.twitter.com/cdBiVPXfbe
— ICMR (@ICMRDELHI) March 31, 2021
The epidemiological case definition for SARS-CoV-2 reinfection was developed from a literature review of data on viral kinetics.
Re-infection with SARS CoV-2 was defined as two positive tests at an interval of at least 102 days with one interim negative test.
Thirty-eight of the 58 eligible patients could be contacted, with twelve (31.6 pc) being healthcare workers, according to the archive-based telephonic survey. Most of the participants had a higher Ct value during their first episode and were asymptomatic.
To conclude, a working epidemiological case definition of SARS CoV-2 re-infection is important to strengthen surveillance.
The current investigation contributes to this goal and records reinfection in 4.5 percent of SARS CoV-2 infected individuals in India, sated the study.
Taking available evidence into consideration, re-infection with SARS CoV-2 in our study was defined as any individual who tested positive for SARS-CoV-2 on two separate occasions by either molecular tests or rapid antigen test at an interval of at least 102 days with one negative molecular test in between,” the study further stated.
While SARSCoV-2 re-infection is still a rare phenomenon, there is a need for an epidemiological definition of re-infection for establishing surveillance systems and this study contributes to such goal,” it said.
However, some of the respondents had a symptomatic second episode as opposed to the first one according to the study. Hence, the rate and duration of hospitalisation were not compared as during the initial phase of the pandemic in India all cases were being hospitalized for at least 14 days, irrespective of symptom severity.
It is not logistically feasible to store the samples of millions of positive cases for future sequencing to identify an important phenomenon like SARS CoV-2 re-infection,” the study said.
Currently, there is no agreement regarding the working definition of re-infection, based only on epidemiological features; a resource-intensive method like whole genome sequencing being the only confirmation.
But the US Centers for Disease Control and Prevention (CDC) has considered the duration of 90 days between two positive SARS-CoV-2 RNA along with genomic evidence of re-infection as an investigative criterion to understand the phenomenon of reinfection.
Both CDC and European CDC suggested the use of genomic evidence for confirmation of reinfection, However, an epidemiological working definition will be more pragmatic and helpful to assess the magnitude of re-infection in most population and resource-constrained settings.