Comprehensive contact tracing study shows children are the biggest contributors to the spread of COVID-19

The largest study related to contact tracing of individuals infected by the COVID-19 suggests that children are a key factor in spreading the virus. The study was jointly done by researchers from Princeton University, Johns Hopkins Bloomberg School of Public Health, the University of California as well as researchers from Government Medical College Andhra Pradesh, India.

In their study, the researchers analyzed 84,965 individuals who contracted the novel coronavirus in the states of Tamil Nadu and Andhra Pradesh in India. Their contacts were traced and 575,071 individuals who came into contact with the aforementioned corona positive patients were included in the study.

The studies show that among 575,071 individuals exposed to the 84,965 confirmed cases, infection probabilities ranged from 4.7 to 10.7% for low-risk and high-risk contact types, respectively. Same-age contacts were associated with the greatest infection risk. Case fatality ratios spanned 0.05% at ages of 5 to 17 years to 16.6% at ages of 85 years or more.

In particular, children and young adults were found to have been the biggest contributors to the spread of the virus. Even though the contact of children was limited due to the closure of schools etc. it was seen that their contact-to-transmission ratio was way higher than adults.

The study also found that 71% of infected individuals did not infect any of their contacts while a mere 8% of infected individuals accounted for 60% of new infections suggesting that superspreading was very common for COVID-19.

Ramanan Laxminarayan, the lead researcher, said, “Our study presents the largest empirical demonstration of superspreading that we are aware of in any infectious disease. Superspreading events are the rule rather than the exception when one is looking at the spread of COVID-19, both in India and likely in all affected places.”

The overall probability of catching coronavirus ranged from 4.7% for low-risk contacts up to 10.7% for high-risk contacts and people had a greater chance of catching the coronavirus from someone their own age.

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