An increasing number of Americans are living in areas with rising COVID-19 cases and hospitalizations, prompting federal and local health officials — including in the country’s two most populous cities — to encourage wearing of masks.
The Centers for Disease Control and Prevention has designated nearly 10 percent of counties in the country as having a “high” COVID-19 community level, triggering its recommendation that residents wear masks indoors in those areas.
A majority of counties in the country remain at “low” and “medium” levels. In those communities, the CDC recommends people wear masks in indoor public transportation settings and if they are at high risk for getting sick.
But in the nation’s two most populous cities — New York City and Los Angeles — local officials are urging residents to wear masks to protect themselves against the virus amid surges in cases and hospitalizations. And in Arizona, every county but one is designated as having a “high” COVID-19 community level.
The CDC encourages all those who live in areas with “high” COVID levels to wear a mask in indoor public spaces.
New York City’s health commissioner on Friday issued an advisory urging people to wear masks in indoor public settings and crowded outdoor settings, warning that COVID-19, the flu, and other respiratory viruses “are seeing unusually high concurrent spikes.”
In Los Angeles, officials are facing the possibility of reinstating an indoor mask mandate in the city should hospitalizations, one of two key metrics that determine mask rules, reach the threshold to trigger such a requirement.
New England has — so far — been spared the CDC’s “high” community level designation. All of Maine and New Hampshire and every county but one in Vermont are considered to have “low” COVID-19 community levels. In Massachusetts, most counties are considered to have “medium” COVID-19 community levels, according to the CDC.
Dr. Shira Doron, an infectious disease physician at Tufts Medical Center, cautioned that the CDC’s data are not completely reflective of the level of COVID-19 circulating in communities, because most COVID-19 cases are now detected by at-home rapid tests, and the CDC’s case rates are based on the results of PCR tests. However, when coupled with wastewater data, which are a leading indicator of COVID-19 surges and are not dependent on results of COVID-19 tests, the numbers indicate a rise in the amount of virus circulating in the US.
“Whether or not it is directly related to Thanksgiving, it appears that starting a few days after Thanksgiving, we entered a period of an upswing in cases and an upswing in hospitalizations,” Doron said, adding that some areas with higher COVID-19 transmission are relatively close to New England, such as New York, but many are in the Southwest and central parts of the country.
While Massachusetts appears to be faring better than other areas of the country, Doron said she expects at least some counties in the state to enter the CDC’s highest COVID level designation soon enough.
A combination of factors are likely fueling the rise of cases and hospitalizations, Doron said. The metrics are escalating at a time when the weather turns colder, and there is evidence that respiratory viruses have a seasonal element.
“It’s probably some combination of perhaps temperature and humidity and it’s probably some bit of behavior and more time indoors,” Doron said. “But it’s not strictly any of those because we see seasonal patterns even in parts of the world that don’t have a lot of changes in weather.”
The other factor is variants. The past few weeks have marked a shift from the prevalence of the Omicron variant BA.5 to BQ.1 and BQ.1.1, Doron said.
“It would not be unexpected that at some threshold, level of prevalence that those two subvariants — which are immune evasive compared to the immunity that has been generated in the population — that that would lead to an increase in cases,” Doron said.
The underlying element to all of these contributing factors is the ebb and flow of immunity “that we’re going to see forever and ever and ever,” Doron said, as people’s protection to viruses circulating increases and then wanes.
“I think what we are seeing now is really what we can expect to see for the rest of time,” Doron said.
Amanda Kaufman can be reached at email@example.com. Follow her on Twitter @amandakauf1.