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COVID-19: CDDEP study indicates children are 'silent' spreaders, pass on virus to 18% close contacts

It's eight months since India reported the first coronavirus infection, and the country's case load is now second in the world, after the US. A major study of the disease in two states -- Tamil Nadu and Andhra Pradesh -- by US-based Centre for Disease Dynamics, Economics and Policy (CDDEP) along with the two state governments shows some unique patterns of transmission.
The study was conducted in August and it covered over 5.75 lakh individuals who were exposed to nearly 85,000 confirmed cases of COVID-19. This is the largest study of the disease conducted anywhere in the world.
The most striking revelation of the study is the role played by super-spreaders. Around 71 percent of those infected did not transmit the virus to anyone else. However, just 8 percent of those infected accounted for 60 percent of all new infections.
So where is the transmission happening? Hospitals and the community in general account for a miniscule amount of COVID infections. Less than 10 percent of transmission happens within the household and more than 79 percent of the transmission happened during conveyance - be it sharing a public bus or other modes of transport.
Children are least likely to die because of the infection. Those under 17 years of age have a mortality rate of 0.05 percent. However, children are "silent" spreaders and they pass on the virus to 18 percent of close contacts, this finding is crucial as India has decided to open schools and colleges with parental consent from October 15.
India's case fatality rate has been less than 2 percent and is one of the lowest in the world. But an age-wise break-up of the deaths shows that more young people are dying in India compared to other countries. The case fatality rate between age 40 to 70 is the highest in India.
About 35 percent of the deaths in India are between age 50 to 64. In the United States, the same age group accounts for only for about 15 percent of the deaths. On the other hand, more than 58 percent of the deaths in the US are above 75 years of age.
In India just under 18 percent of those dead are above the age of 75. To discuss the findings of the study, Shereen Bhan spoke to Dr Shahid Jameel Virologist, Ramanan Laxminarayan of Center for Disease Dynamics, Economics & Policy (CDDEP) and B Chandra Mohan Principal Secretary of Tamil Nadu government.