Still, the campaign to vaccinate more Americans cannot let up until children are protected, they said. Half of respondents said at least 80 percent of Americans, including children, would need to be vaccinated before it would be safe to do most activities without precautions. Though children are less likely than adults to develop severe cases of Covid-19, the scientists said their immunity was important because they could be hosts for the virus and a way for it to continue to circulate or develop new variants. “Children cannot be left out of the equation as we reopen,” said Corinne McDaniels-Davidson, the director of the San Diego State University Institute for Public Health. “The ideas that they cannot transmit Covid or are immune from disease are pervasive among the lay public. We need education here.” In assessing when the acute phase of the Covid pandemic could be considered over, they said vaccinations were more relevant than other metrics like new cases, hospitalizations or deaths (because an effective vaccination campaign would lower those rates, they said).