On the Medical Watch: Babies fighting COVID-19. Unlike some of the sickest adults, infants show a rare resiliency to the virus. The news came as a surprise even to those on the frontline, and now doctors are documenting the experience so we can all learn from the youngest patients.

At the height of the outbreak, the city stopped. But inside Lurie Children’s Hospital, the work carried on caring for the youngest patients with COVID-19.

“Although the vast majority of cases are in older children and adolescents, we certainly have had many infants that have tested positive for SARS-CoV-2 which is the virus that causes covid-19,” Dr. Leena Mithal, Lurie Children’s infectious diseases specialist, said.

Doctors there have diagnosed more than 600 pediatric patients with the virus. One in six required hospitalization, and of those admitted — one in six required intensive care, typically due to an underlying medical condition. But it’s been the tiniest patients — infants — who have contradicted the typical course of disease found in older children and adults.

“The vast majority of infants had fever for a couple days and had some mild cough but were well without fever at the time of discharge and most infants stayed in the hospital for one to three days so we’re seeing a shorter disease course as well as more mild symptoms,” Mithal said.

Mithal and her colleagues studied 18 of the infants, ages three months and younger, diagnosed with COVD-19 at Lurie between April and May. What set them apart from older pediatric patients? A much higher viral load, yet none of the babies were severely ill and none required intensive care or ventilation. 

“More studies need to be done to understand those viral kinetics are did we just pick up those infants on day one or two of infection and early in their symptoms and thus they had a higher viral load or is there something unique about the immune system in infants that allows them not to have the inflammatory response in the same way as adults and thus get severely ill,” Mithal said.

There were other findings that reflect some of the racial disparities seen among COVID-19 patients.

“Our specific cohort was largely Latinx over 80% and although our ER proportion of Latinx ethnicity has not changed over this timeframe the proportion of young infants with COVID who are of Latinx ethnicity is disproportionately high,” Mithal said.

Mithal says it appears the infants likely acquired the infection from their household contacts. None of the babies in the study tested positive at birth.

“It may be related to factors such as the number of persons living in a household perhaps working outside of the household and then access to primary care and pediatric care,” Mithal said.

The study in infants is a small step to better understanding the spectrum of disease in all ages.

“Infants, children and adolescents, adults, older adults affecting all of these age groups and in each of these age groups there is a risk of having complications and we’re still understanding what those risk factors are,” Mithal said.

The Lurie findings do not reflect early data out of China, which showed a greater risk for severe infection in younger patients.