In the U.S., only about 31.6 percent of eligible people were fully vaccinated as of Monday morning, and that number varies a lot from place to place — 23.8 percent of Alabamians were fully vaccinated compared with 40.2 percent of Mainers, and you can assume counties and cities show this same kind of variation. That leaves a lot of people who can still contract COVID-19, and I wondered whether young kids could end up being a conduit that keeps COVID-19 moving through the population even as vaccination rates rise.

As with many aspects of COVID-19, this question doesn’t yet have absolute, unequivocal answers. When I asked Yair Goldberg, a professor at the Technion-Israel Institute of Technology who is studying how COVID-19 spreads in that country, he said that his team wasn’t yet ready to talk about the data they’re collecting. Even a year in, we’re still learning as we go.

But other researchers told me that evidence suggests grade-school kids are not a major driver of COVID-19’s spread in communities — at least, that is, so long as they’re following mitigation strategies like wearing a mask.

For example, even after many school districts had been open for a while last fall and case numbers were rising to a surge, a study modeling the spread of COVID-19 in the U.S. found that children age 9 and under were responsible for only about 5 percent of the transmissions happening at the time. And those results line up with what researchers are seeing in other countries. Kids in the U.K. can and do get infected and spread COVID-19, said Rosalind Eggo, a professor and infectious disease modeler at the London School of Hygiene and Tropical Medicine. But so far, she said, cases among kids aren’t rising before cases in adults, a sign that would indicate they were the ones driving infection.

The fact that kids don’t seem to be a leading source of COVID-19 transmission is a bright spot in this whole sad, sorry year.

 Young children do transmit the virus, and variants like the more-transmissible B.1.1.7 lineage increase how likely kids are to spread COVID-19. It’s also important to note that those low rates of children transmitting COVID-19 are very dependent on behavioral modifications — in particular, wearing masks indoors. A brand-new study out on Thursday found that risk-reduction strategies like teachers wearing masks, kids wearing masks, checking symptoms daily and canceling extracurricular activities like sports made the difference between in-person schooling that spread COVID-19 from kids through their families and in-person schooling that didn’t significantly increase the spread of COVID-19.

All this means that vaccinated parents should not go around treating their unvaccinated children as extensions of themselves, said Dr. William Raszka, a pediatric infectious disease specialist at the University of Vermont Medical Center. There will be situations where two vaccinated adults can safely hang out mask-free but their unvaccinated kids can’t.

Read the full article about unvaccinated children by Maggie Koerth Baker at FiveThirtyEight.