NEW DELHI: A case of four healthcare workers having developed severe Covid-19 requiring hospitalisation, weeks after being recovered from the disease with mild symptoms, has been documented in India.
The findings of the study have dashed expectations that the second infection with coronavirus should be milder.
The study was conducted by researchers associated with two hospitals in Mumbai, International Centre for Genetic Engineering and Biotechnology and CSIR-Institute of Genomics and Integrative Biology in Delhi.
So far, while it has almost been established that re-infection with SARS CoV 2 in people is possible, there have been very few instances where the repeat infections have been found to be worse than the first episodes, despite the presence of neutralising antibodies.
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The researchers associated with Kasturba Hospital for Infectious Disease and P D Hinduja Hospital in Mumbai, apart from the two scientific institutions found that for all four HCWs, the second episode was accompanied by worse symptoms, constitutional manifestations, and illness that lasted longer than the first episode.
Also, all required hospitalisation and treatment with one patient undergoing plasma therapy while another was unable to return to routine activities and work for three weeks, said the study which is under peer-review for publication in The Lancet.
All of these patients had the first infection in May and June but they again developed symptoms in July. The researchers established the presence of the virus in the two episodes of infection through the detailed genome sequencing
“While the evidence of people developing severe episodes of re-infection is rare, our work has clearly manifested that doctors and people need to be very careful even after they recover from the disease once,” said Dr. Anurag Agarwal, a scientist with the CSIR-IGIB who is a co-author of the study.
He added that there were three key takeaways from the study- that immunity is not guaranteed despite infection, protection against the virus may be short-lived and bad disease the next time, though rare, is a possibility.
In the paper, the authors have noted that while none of the HCWs developed lower respiratory tract manifestations or breathlessness, this may be explained by their young age.
“Older HCWs may experience more severe respiratory involvement,” they said, adding that as for those who recover from mild Covid-19 have short term immunity, reinfections may become more common in the future.
Incidentally, the paper has come out weeks after two cases of reinfection were reported in the country—both of which were found without any symptoms in the later episodes.
Some independent scientists meanwhile raised concerns saying that since the only laboratory evidence of the first infection in such cases has been a single pharyngeal PCR swab, it could also be a case of contamination rather than an actual case of infection the first time.
“As per my knowledge, reinfections are very few to be true possibilities,” said a senior immunologist who did not want to be named. “This can be clearly resolved if the researchers have DNA samples from the first swab which can then be used to ascertain the patient’s identity,” he said.