TONYA MOSLEY, HOST:
Researchers in India have just released the largest study ever looking at transmission patterns of the coronavirus among more than half a million people in that country. The study found that most people never pass on the virus, but others pass it on readily. And as school districts in many parts of the world look to reopen, NPR's Jason Beaubien reports this study found children play a major role in transmission.
JASON BEAUBIEN, BYLINE: India unfortunately has become an ideal place to study the spread of COVID-19. Recently, the country has been reporting nearly 100,000 new cases per day. Testing is widely available. And in the states of Tamil Nadu and Andhra Pradesh, public health workers are aggressively tracking local infections.
RAMANAN LAXMINARAYAN: They are wealthier states. They have better-developed systems. And they also have this entire apparatus that was set up for HIV/AIDS for contact tracing, so they know how to do this.
BEAUBIEN: That's Ramanan Laxminarayan, the director of the Center for Disease Dynamics, Economics and Policy in New Delhi and one of the lead authors of the study. Among the key findings are that 8% of people who get COVID are responsible for 60% of the spread. Sitting next to someone who's positive on a bus or a train for more than six hours puts you at the highest risk of getting infected. And finally, children are playing a significant role in transmission.
LAXMINARAYAN: The proportion of asymptomatics among children was much higher than in other populations. So kids are silent spreaders in the sense that they don't manifest the disease with symptoms. They just happen to get infected as much as anyone else, and then they actively spread it to other people.
BEAUBIEN: And Laxminarayan says kids seem most likely to spread it to other children. Judy Guzman-Cottrill, a pediatric infectious disease professor at Oregon Health and Science University who wasn't involved in this study, says this report is significant because of how large it is.
JUDY GUZMAN-COTTRILL: I think we've learned some really important points here.
BEAUBIEN: Contact tracers didn't just investigate 85,000 primary COVID cases. They actually went out and tested nearly 600,000 contacts of those initial cases to figure out when, where and to whom the virus had spread. Guzman-Cottrill says there's been a lot of questions and not a lot of solid research about how readily it can transmit among children.
GUZMAN-COTTRILL: I've been skeptical since the beginning of the pandemic of the early studies that showed that kids do not spread this virus. It just doesn't make sense from a perspective as a pediatric infectious disease physician, especially a respiratory virus.
BEAUBIEN: According to the Centers for Disease Control and Prevention, nearly a half a million kids in the U.S. have tested positive for the virus so far. CDC data also show that those kids are far less likely to get hospitalized or die than older people. But the sheer number of cases among young people is rising. This week the American Academy of Pediatrics released a study showing that more than 10% of all cases nationwide are in children compared to just 2% being among kids back in April.
Jason Beaubien, NPR News.
(SOUNDBITE OF WOLF ALICE SONG, "TURN TO DUST")
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.