Period. 29 September - 5 October 2020
  • A new paper in Science provides early results from the world’s largest contact tracing study examining COVID-19 transmission dynamics in dense, low resource areas. The research team from Princeton sampled 575,071 residents from two Indian provinces (Tamil Nadu and Andhra Pradesh) that were exposed to 84,965 confirmed cases of COVID-19. Among the most notable study findings was the role of ‘superspreading’ events by a small proportion of those infected. For example, 71% of individuals with confirmed cases of COVID-19 did not infect close contacts, while only 8% of infected individuals accounted for 60% of new infections. The authors also present the first large-scale evidence that India’s country-wide shutdown contributed to a substantial reduction in transmission by reducing the opportunity for ‘superspreader’ events. Based on a sampling of over half a million residents, the study estimates the chance that an individual (regardless of age) would pass the virus to a stranger or family member was remarkably low at 2.6% and 9%, respectively. The research team furthermore demonstrate how children and young adults constituted a third of all cases, with the former an especially effective vector of transmission in resource limited settings.

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