In one of the first studies to explore how COVID-19 specifically affects older infants, researchers found that the number of infected people in a household was the factor most closely linked with the infant’s likelihood of being infected.

Infants whose mothers test positive for COVID-19 tend to develop less-severe symptoms than their parents, if they become infected with the virus at all.

“The focus on infants early in the pandemic was about possible transmission risks during pregnancy, birth, or through breastfeeding, but there were other questions about the risks in the household to infants and other children when caregivers are sick,” says Melanie Martin, assistant professor of anthropology at the University of Washington and first author of the study in Frontiers in Immunology.

“Infants are in the most contact, and very close contact, with their caregiver than with any other family members. And so we asked, how much are infants at risk, and how do you protect children when they are sick?”

The study analyzed surveys and antibody results (taken from pin-prick blood samples) of 46 pairs of COVID-positive mothers and their infants for two months following maternal infection. Infants were at least 1 month old, and COVID-positive mothers were enrolled in the study within days, sometimes hours, of receiving their positive PCR test results.

The researchers also recruited a comparative group of 11 COVID-negative mothers, who tested negative after exposure or symptoms, and a control group of 26 mothers with no known COVID exposures or symptoms.

In all, about half of the infants of COVID-positive mothers developed symptoms or antibodies indicative of COVID-19 infection. The rates of infection and symptoms in those infants were similar to those of other household children, but lower than for fathers and other household adults.

None of the COVID-negative mothers or their infants tested positive for SARS-CoV-2 antibodies, including one infant who tested PCR positive. While nearly half of the mothers in the control group had antibodies targeting SARS-CoV-2, likely signaling a previous infection they were unaware of, none of their infants did.

Infant age and maternal symptoms were not associated with risk of infection among infants of COVID-positive mothers, but families with greater numbers of infected family members were more likely to have infants who had tested positive.

Read the full article about infants, caregivers, and COVID-19 by Kim Eckart at Futurity.