10 in Chennai test Covid-19 positive after recovery

CHENNAI: At least 10 patients returned to four government medical college hospitals in the city with Covid-positive reports days or weeks after they were declared cured. But doctors say they have no evidence to show if these are relapses or reinfections. There is no registry of number of such patients in private hospitals.
Infectious disease experts and virologists say the state must do a larger genome study to understand why some people have symptoms of the virus — mild or severe — days after they test negative. In the last two weeks, scientists in the US and Hong Kong said they were able to use sophisticated testing to prove that the virus associated with each instance of their patient’s infection represented genetically different strains. “Readmissions with Covid symptoms can be because of a reinfection or a relapse,” said Omandurar Medical College dean Dr R Jayanthi, where at least two cases of readmission were reported. “We will know the difference only when we isolate the gene and analyse it. If the genes are different, then it is a possible reinfection. The same strain causes a relapse,” she said. International organisations such as WHO said they are studying scientific papers emerging from different countries.
In the city, at least two doctors from the Government Women and Children hospital in Egmore were readmitted days after they tested positive in the last one month. One of them tested positive for dengue in addition to Covid-19. “She had all the symptoms of dengue including body pain. We don’t know if it was a false positive for dengue. But she has been showing signs of Covid-19,” said institute director Dr Vijaya. She is currently under treatment at the Omandurar Medical College Hospital, she said. A CRRI resident, who was posted on hospital duty at the Kilpauk Medical College Hospital, is also in the isolation ward of the hospital. He was first tested in May after he had a “high-risk” exposure. “He was asymptomatic then and tested negative a few days later.On September 1, we tested him again when he had fever, cough and loose stools. He was positive, but has now been asymptomatic for a few days,” said Kilpauk Medical College Hospital dean Dr P Vasanthamani.
Treating doctors say most patients have mild symptoms the second time. In some people, the virus invades the lungs. “But so far, we haven’t seen serious complications or deaths in cases of reinfection as of now,” said Rajiv Gandhi Government General Hospital dean Dr Therani Rajan. The hospital has reported at least five cases of readmission. Recently, a senior police officer tested positive days after he was tested negative. “The infection was very mild. We have been kept in home isolation,” he said.
Some doctors, like Stanley Government Hospital professor of medicine Dr Sridhar, say inaccuracies of the RTPCR negatives should not be ruled out while looking for evidence of a reinfection. “The sensitivity of RTPCR is just 70pc. So there is a good chance that the virus was still harbouring even though it did not show up in the exit test,” he said. But others say possibility of reinfection, though rare, must not be ignored. “If proven, it may indicate that initial exposure to the virus may not result in full immunity for everyone. More importantly, it can provide vital clues for vaccine development,” said senior infectious diseases expert Dr Subramanian Swaminathan. It is increasingly believed now that it is not the innate immune response – the white blood cells fighting the virus – and the system will not give immunity to the virus, he said. “Scientists think the body needs an adaptive immune response. This means, cells that produce targeted antibodies stick to the virus and stop it. It is a cellular response where T cells attack just the cells infected with the virus,” he said.
Meanwhile, King Institute of Preventive Medicine has sent samples to the National Institute of Virology in Pune to study the gene that is circulating in the community. Institute director Dr K Kaveri said samples have been sent so viral isolation can be done in a lab that has the highest bio-safety measures. “We are still awaiting reports,” she said.
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