'Need to be on a higher alert': Babies and toddlers more likely than teens to transmit coronavirus, study says

As school and state officials debate mask and vaccine mandates, parents of children returning to in-person learning worry their kids are more likely to bring the coronavirus back home with them.

While parents pay extra attention to their school-age children, health experts said, they shouldn’t let their guard down at home around toddlers and babies. A study published Monday in JAMA Pediatrics suggests they’re more likely than teens to transmit the virus to other members of the household. 

Researchers from Public Health Ontario, a Canadian public health agency, looked at 6,280 households with sick children from June to December 2020, grouping them into four age categories: 0 to 3, 4 to 8, 9 to 13 and 14 to 17.

Though teens were more likely than babies and toddlers to get infected with COVID-19, making up 38% of cases compared with 12%, a statistical model showed those 0 to 3 years old were more likely than their older counterparts to transmit the virus. 

“Earlier on, we thought little children weren’t big vectors of the disease,” said Dr. Patricia Emmanuel, professor and chair of pediatrics for University of South Florida Health Morsani College of Medicine, who is unaffiliated with the study. “But this study shows and reinforces that they can.”

This doesn’t necessarily mean babies and toddlers are more infectious than teens and young children, health experts said. They may be more likely to transmit the virus to parents and other caregivers because they’re often in close contact.

“Those (age) groups tend to require more care and physical interaction and are not adherent to hygiene practices and masking,” said John Brownstein, an epidemiologist  and chief innovation officer at Boston Children’s Hospital. 

Overall, more than 27% of households in the study experienced secondary transmission in which a sick child infected other family members or caregivers. Health experts said children are more likely to transmit to household members because of the highly contagious delta variant.

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Cases and hospitalizations among children are on the rise, and the delta variant makes up about 90% of new infections among kids, according to experts. Just days into the new school year, thousands of children and staff are under quarantine in school districts after being exposed to COVID-19.

“We’re seeing the most amount of kids with COVID since the beginning of the pandemic and the most amount hospitalized,” Brownstein said. “That may be related to the amount of transmission in the community and the major surge of delta among unvaccinated populations. So that’s a real concern for the pediatric population.”

Health experts said vaccination is the best way to protect parents from getting sick if their child brings home the virus. It also decreases the risk of bringing home the virus to unvaccinated children.

“Being vaccinated is clearly the biggest tool in both directions,” Brownstein said. “Vaccinated parents create a better cocoon for kids to prevent illness.”

Children 12 and older are eligible to receive the Pfizer-BioNTech vaccine, and those 16 and older can get Moderna's. Health experts said younger children who aren't eligible can protect themselves and prevent transmission by wearing masks and practicing good hand hygiene.

They recognize the same rules may not apply to babies and toddlers.

“This study sort of does indicate that it’s not a one size fits all when it comes to kids,” Brownstein said. “There are important nuances based on both biological differences but also behavioral. We have to be thoughtful in terms of various age groups and ways in which we might intervene in terms of transmission.”

Emmanuel urges parents and caregivers to wear masks while caring for babies and toddlers with suspected or confirmed COVID-19 to prevent further transmission in the household. She recommends washing their hands after every feeding, diaper change or contact with bodily fluids.

Brownstein suggested limiting contact with other members of the household.

“With the delta variant, we all need to be on a higher alert for symptoms and be more cautious overall,” Emmanuel said.

Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT. 

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.