Centers for Disease Control and Prevention advisers will meet Tuesday to discuss who should get coronavirus vaccines first.

One population they may consider prioritizing: Americans who are obese - a major risk factor for severe covid-19 that some experts say has gone underrecognized.

"Obesity was ignored for the longest time and overweight was completely ignored," said Barry Popkin, an obesity researcher at the University of North Carolina at Chapel Hill. Now the CDC is talking about both, he said.

The agency has already laid out four groups that should be considered for priority: health-care personnel, workers in essential and critical industries, older adults, and people with certain underlying medical conditions - including "severe obesity." But it's unclear to what extent the CDC's Advisory Committee on Immunization Practices will prioritize this group.

There's been much discussion about how underlying medical conditions such as hypertension and Type 2 diabetes are associated with higher risk of dying from the coronavirus. But these conditions are most frequently found in people who are obese - making it difficult to discern whether the medical conditions or the obesity were the biggest factors at play.

The evidence, Popkin argues, points to extra weight as a bigger risk factor than any individual comorbidity. That's because people who are overweight or obese have more body fat - which is more hospitable than other tissue to the coronavirus - and they suffer from reduced lung capacity.

"Being an individual with obesity independently increases the risk of influenza morbidity and mortality, most likely through impairments in innate and adaptive immune responses," according to a paper Popkin wrote over the summer, which analyzed 75 studies on the connection between covid-19 and body mass index.

Popkin and colleagues found that people with obesity were 113 percent more likely to be hospitalized, 74 percent more likely to be admitted to intensive care units and 48 percent more likely to die of covid-19.

The connection helps explain some of covid-19's impact on Black and Hispanic Americans, who have died at disproportionate rates from the disease and are also more likely than White Americans to be obese.

Great Britain is prioritizing its most obese population for vaccination. Its public health agency posted guidance last week saying that morbidly obese people - defined as those with a body mass index over 40 - should be prioritized for vaccines ahead of those younger than 65. This "at-risk" group also includes people with asthma, kidney disease and weakened immune systems.

But the prioritization doesn't extend to obese people who don't meet this threshold - despite the research showing they may still be at much higher risk for hospitalization, intubation and death from covid-19.

About 28 percent of British people are considered obese. Rates are even higher in the United States, where a record 42 percent of Americans now meet the obesity threshold.

The sense of urgency to get a vaccine approved and distributed is only intensifying.

The CDC's Advisory Committee on Immunization Practices announced on Friday that it is holding an emergency meeting Tuesday, presumably due to the speed at which several drugmakers are moving to get their coronavirus vaccines approved by the Food and Drug Administration. A separate panel of advisers to the FDA will meet next week to consider a request from Pfizer for emergency approval, and Moderna has announced it will file a request for emergency use of its vaccine.

As record numbers of Americans test positive for the virus, health providers are bracing themselves for a post-Thanksgiving bump in cases that experts are calling a surge on top of a surge.

"What we expect, unfortunately . . . we might see a surge superimposed on the surge we're already in," Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said Sunday on CNN.

"The holiday, which is typically one of the busiest travel periods of the year, fell at a particularly dire time in the pandemic," The Washington Post Sarah Kaplan reported. "Some 4 million Americans have been diagnosed with the coronavirus in November - twice the previous record, which was set last month. More than 2,000 people are dying every day. Despite that, over a million people passed through U.S. airports the day before Thanksgiving - the highest number of travelers seen since the start of the outbreak."

The weekend brought some bleak indicators. Hospitalizations in the United States exceeded 90,000 people for the first time on Thanksgiving Day. And experts warn it will only get worse in two or three weeks, when infections contracted during holiday travel turn into serious cases of covid-19.

"I fully expect on a national level we will see those trends continue of new highs in case counts and hospitalizations and deaths," Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security, told Kaplan.

The Washington Post's Alexandra Ellerbeck contributed to this report.