A new study out of Italy’s hardest-hit region early in the pandemic shows that children and young adults developed symptoms at a far lesser rate than older case contacts after exposure to a COVID-19 case. The study was published yesterday in JAMA Network Open.

The findings were based on 5,484 quarantined close contacts of confirmed cases in the Lombardy region. Half of the close contacts (2,824, or 51.5%) tested positive for COVID-19, but most did not develop respiratory symptoms or fever: Only 26.1% (95% CI, 24.1%-28.2%) of infected individuals younger than 60 years developed respiratory symptoms or fever, the authors wrote. Among infected participants older than 60 years, 6.6% (95% CI, 5.1%-8.3%) developed critical disease.

Only 18.1% of case contacts under the age of 20 developed symptoms, compared with 64.6% of case contacts over the age of 80. The authors also found some difference between male and female close contacts.

“No significant differences between SARS-CoV-2–infected female and male patients were found in the risk of developing symptoms, whereas female patients were 52.7% (95% CI, 24.4-70.7) less likely to experience critical disease than male patients,” the authors wrote.