Can one get re-infected with Coronavirus after recovering from it once? To understand the cases of re-infection SARS-CoV2, the Indian Council of Medical Research (ICMR) recently constituted a team of scientists to identify the most possible cases of reinfection of Coronavirus. The scientists examined 1,300 cases of reinfection in the country who had got infected with the virus twice, back to back. The ICMR scientists undertook the study in the wake of uncertainty around the world about the chances of re-infection with Coronavirus. Scientists around the world are trying to understand how long does the immunity against Coronavirus last once the patient has recovered from the disease. Definite answers around the question of Coronavirus re-infection could also help in formulating a better strategy against the pandemic, The Indian Express reported.
What are the findings of the study?
The ICMR study found that out of the 1,300 cases of reinfection in the country, only 58 of them could be truly classified as cases of reinfection. The scientists found that in these 58 cases, the reinfection had taken place after 102 days the patients had recovered from the virus for the first time. The study also found that these patients also tested negative in-between during the 102 days.
According to the study which also got published in the Epidemiology & Infection journal, the scientists found that the actual cases of reinfection of Coronavirus were very less as in most of the patients the scientists found “persistent viral shedding” which means that low levels of Coronavirus continued to exist in their bodies after recovering from the disease for up to three months. The scientists found that the levels of virus were so low that it was neither sufficient to make the patient feel sick or lead to spread of the disease to others. However, even the low levels of virus can get traced in the Coronavirus testing and the report may turn out to be positive for the second time.
How can reinfection of Coronavirus be confirmed?
As per the ICMR study, the only conclusive way to confirm actual re-infection could be done with the help of genome analysis of the virus sample. Since the virus mutates continuously, the genome samples in case of re-infection would also show some differences. Genome sampling may be a conclusive way of finding whether the patient has got re-infected with the virus but it cannot be undertaken in every case as it is a very complex process that takes both intense efforts and time. For most of the cases of re-infection, there is no genome sample available from the first instance of infection.
In the first confirmed case of Coronavirus reinfection which was traced in Hong-Kong in August last year, the scientists had been lucky as they had sent the genome samples of the 33-year-old patient even when he first got infected with the virus. When the same patient contracted the virus again, the genome samples from the first and second instance could be compared.
Did the ICMR study also rely on Genome sequencing?
No, genome sequencing was not studied by the ICMR scientists due to a lack of genome samples data. The scientists instead relied on analysing those patients who had reported getting re-infected with the virus for the second time after a gap of more than 102 days. The figure of 102 days was agreed to after the Centers for Disease Control, US, said that viral persistent shedding of Coronavirus in small levels can continue among the recovered patients till 90 days.
As an additional safeguard, the scientists only considered those cases as actual re-infection in which the patient had tested for Coronavirus during the 102 days period and tested negative at least once during the period
Takeaways from the study
Until genome sequencing is studied, the 58 cases zeroed in by the ICMR could still not be 100% classified as re-infection. However, the scientists from the ICMR concluded that permanent immunity among people who have got infected with the virus cannot be assumed. The scientists also said that since genome sampling cannot be identified in all cases of Covid-19 re-infection, scientists would have to arrive at a consensus to find alternative methods to trace likely cases of reinfection.