The top US health body has issued new guidelines on the reopening of schools, clearly weighting its recommendations in favor of having students return to their classrooms in fall.
The updated advice from the Centers for Disease Control and Prevention (CDC) was posted Thursday night, and came a few weeks after the agency was asked to change course by President Donald Trump.
"We owe it to our nation's children to take personal responsibility to do everything we can to lower the levels of COVID-19, so they can go back to school safely," CDC chief Robert Redfield said Friday.
With the virus still rampant in many parts of the country, a number of cities including Houston and Los Angeles have already announced that schools will reopen virtually.
Others like New York, where the epidemic has receded, are opting for a hybrid model.
The CDC's earlier guidelines had emphasized extreme caution, but the agency was asked by Trump earlier this month to revisit the topic.
The new advice reads: "Schools are an important part of the infrastructure of communities and play a critical role in supporting the whole child, not just their academic achievement."
Although it says schools must take into consideration local virus transmission rates, the CDC offers no precise guidance on what the cut-off threshold should be.
Asked by a reporter how he would define a hotspot that should not yet reopen its schools, Redfield said: "Right now we're looking where the percent positivity rate within the community is greater than five percent."
"Positivity" refers to the rate of positive tests, and the World Health Organization (WHO) considers a rate of above five percent to indicate rampant community spread.
Officials will be looking at data on the county level, but as a barometer, only 17 states plus the US capital currently fulfill this requirement on a statewide basis.
Redfield however stressed it was "just guidance to consider to be more cautious."
The scientific community's position on schools has been evolving in light of new evidence.
The risk of children becoming seriously ill from COVID-19 is low, while pediatricians emphasize the beneficial role schools play in children's social development and mental health.
According to the CDC, prolonged school closures could worsen achievement gaps across income levels and racial and ethnic groups.
A study of 800,000 students by researchers at Brown and Harvard Universities looking at how an online math program called Zearn was used found that student progress decreased throughout late April, particularly in low-income areas.
Officials also have said that identifying cases of child abuse is easier when students are present in their classrooms.
The US capital Washington saw a 62 percent decrease in child abuse reporting calls compared to last year, but severe cases of child abuse were nevertheless spotted in emergency rooms.
The CDC concluded: "The best available evidence from countries that have opened schools indicates that COVID-19 poses low risks to school-aged children, at least in areas with low community transmission, and suggests that children are unlikely to be major drivers of the spread of the virus."
