Twelve children who likely contracted Covid-19 at three childcare operations in Utah infected some of their parents and siblings, according to a US study, adding to evidence that very young kids can transmit the disease.
Previous studies had suggested children aged 10 years or older can efficiently transmit Covid-19 in school settings.
The new study by the Centres for Disease Control and Prevention (CDC) published on Friday found that much younger children can also spread the virus, including a case of an 8-month-old who apparently infected both parents.
From the 12 documented cases acquired at the childcare facilities, virus transmission was found among at least 12 of 46 non-facility contacts, such as parents - one of whom required hospitalisation - siblings and an aunt.
Transmission was observed from two of three children with confirmed, asymptomatic Covid-19, researchers found, further evidence that those without symptoms can spread the virus.
From April 1 to July 10, Salt Lake County identified 17 childcare facilities, including daycare centres and day camps, with at least two confirmed Covid-19 cases within a 14-day period. Data in the CDC report involves only outbreaks in three of these.
At two of the facilities, the researchers traced the primary infection to staff members exposed to Covid-19 through a family member. The source of the outbreak at the third facility was not identified, making it possible its cases resulted from an infection that originated elsewhere, researchers said.
CDC noted other limitations to the study that could have impacted the data collected, including changes in contact tracing methodology during the pandemic and testing criteria that initially included only persons with typical Covid-19 symptoms.
Still, researchers said, having Covid-19 testing available and regularly testing contacts of those infected in childcare settings, including those without symptoms, could help prevent family members from becoming infected.
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