Mary-Lou McCullagh, 83, and her husband Bob, 84, greet Axel Stirton, 2, the little boy who lives across the street April 3, 2020 in Ventura, California. Mary-Lou and Bob are in isolation from the Covid-19 pandemic, trying to ensure that they do not come in contact with the virus.

Most kids infected with the coronavirus develop only mild symptoms and typically recover within two weeks, according to a study published Wednesday in JAMA Pediatrics.

However, it found that some children become seriously ill, including a 13-month-old infant who was admitted to intensive care.

Researchers in Italy analyzed 1,065 Covid-19 patients, mostly in China, under age 19. They analyzed studies published between Dec. 1 and March 3. At least 444 of the patients were younger than age 10, while 553 were ages 10 to 19.

Most children were reported to have mild respiratory symptoms, namely fever, dry cough, and fatigue or were asymptomatic, meaning they produced no symptoms, the researchers said. Many of the children were hospitalized, but most kids with symptoms required only supportive care and didn't need oxygen or assisted ventilation, they said. No children under age 9 died, but one death was reported in the 10-19 age range.

One 13-month-old infant with Covid-19 did develop severe complications, however. The infant developed vomiting, diarrhea, fever and pneumonia, complicated by shock and kidney failure that required intensive care, the researchers said. One study also described a 30-hour-old newborn who developed breathing problems after acquiring the infection from the mother.

"Unlike adults, children do not seem to be at higher risk of severe illness based on age and sex," wrote Riccardo Castagnoli, a Ph.D. candidate at the University of Pavia and a lead author of the analysis. "However, at present, no data are available on the role of comorbidities in the severity of pediatric COVID-19."