AsianScientist (Oct. 27, 2020) – In one of the largest and most comprehensive analyses of COVID-19 epidemiology to date, researchers from the Center for Disease Dynamics, Economics & Policy (CDDEP) in India have found that although children are less severely impacted by the disease, they can play a key role in the transmission of SARS-CoV-2. Their findings have been published in Science.
Although we have learnt much about the novel virus SARS-CoV-2 in the last ten months, many key aspects of how the virus behaves and interacts with humans remain unknown. One of the most important unknowns is how the virus is transmitted. To fill this gap, researchers studied disease transmission patterns in 575,071 individuals exposed to 84,965 confirmed cases of COVID-19 from Andhra Pradesh and Tamil Nadu, India.
These two highly populous states are known for their effective primary healthcare delivery models, large healthcare workforce and high public health expenditures per capita. Both states initiated rigorous disease surveillance and contact tracing early in response to the pandemic, including syndromic surveillance and SARS-CoV-2 testing for all individuals seeking care for severe acute respiratory illness or influenza-like illness at healthcare facilities; delineation of five-kilometer ‘containment zones’ surrounding cases for daily house-to-house surveillance to identify individuals with symptoms. They also conducted a daily follow-up of all contacts of laboratory-confirmed or suspect COVID-19 cases, with the aim of testing these individuals 5-14 days after their contact with a primary case to identify onward transmission.
In agreement with previous studies, the researchers found that young children aged 5-17 years old had the lowest case fatality ratios (0.05 percent), and that case fatality ratios increased with age, reaching 16.6 percent in those above 85. However, unlike observations in high-income settings, deaths in India are concentrated at ages 50-64 years.
Interestingly, the study found a high prevalence of infection among children who were contacts of cases around their own age. Furthermore, while 70 percent of infected individuals did not infect any of their contacts, just eight percent of infected individuals accounted for 60 percent of observed new infections. These results are the largest empirical demonstration that superspreaders are driving the transmission of COVID-19.
The study also showed India’s country-wide shutdowns were effective, substantially reducing the reproductive number of the virus.
“This study was made possible by the significant contact tracing effort in Andhra Pradesh and Tamil Nadu, which involved tens of thousands of healthcare workers. The results on disease transmission and mortality have the potential to inform policy to fight COVID-19. The study also speaks to the capacity of research emerging from India to help inform the global response to COVID-19,” said director of CDDEP, Dr. Ramanan Laxminarayan.
The article can be found at: Laxminarayan et al. (2020) Epidemiology and Transmission Dynamics of COVID-19 in Two Indian States.
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Source: Center for Disease Dynamics, Economics & Policy; Photo: uzhursky/Shutterstock.
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