India’s massive COVID surge puzzles scientists, initial antibody data may have been too narrow.

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Thu, 2021-04-22 02:05 — mike kraft

India’s massive COVID surge puzzles scientists The virus is spreading faster than ever before in India despite previous high infection rates in megacities, which should have conferred some protection. Smriti Mallapaty Nature

The pandemic is sweeping through India at a pace that has staggered scientists. Daily case numbers have exploded since early March: the government reported 273,810 new infections nationally on 18 April. High numbers in India have also helped drive global cases to a daily high of 854,855 in the past week, almost breaking a record set in January.

Just months earlier, antibody data had suggested that many people in cities such as Delhi and Chennai had already been infected, leading some researchers to conclude that the worst of the pandemic was over in the country.

Researchers in India are now trying to pinpoint what is behind the unprecedented surge, which could be due to an unfortunate confluence of factors, including the emergence of particularly infectious variants, a rise in unrestricted social interactions, and low vaccine coverage. Untangling the causes could be helpful to governments trying to suppress or prevent similar surges around the world.

... India’s daily totals are now some of the highest ever recorded for any country, and are not far off a peak of 300,000 cases seen in the United States on 2 January.

COVID-19 case numbers started to drop in India last September, after a high of around 100,000 daily infections. But they began to rise again in March and the current peak is more than double the previous one. ...

One explanation might be that the first wave primarily hit the urban poor. Antibody studies may not have been representative of the entire population and potentially overestimated exposure in other groups, he says.

The antibody data did not reflect the uneven spread of the virus, agrees Gagandeep Kang, a virologist at the Christian Medical College in Vellore, India. “The virus may be getting into populations that were previously able to protect themselves,” she says. That could include wealthier urban communities, in which people isolated during the first wave but had started mingling by the second. ...

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