Amid a rise in COVID-19 cases across the U.S., hospitalizations among fully vaccinated people are also increasing, raising questions about waning vaccine immunity and whether booster doses will eventually be required to be considered fully vaccinated.
"What we're starting to see now is an uptick in hospitalizations among people who've been vaccinated but not boosted," said Anthony Fauci, MD, director of the National Institute for Allergy and Infectious Disease. "It's a significant proportion, but not the majority by any means," he told NBC News Nov. 17.
More than 31.4 million people — about 16 percent of the country's fully vaccinated population — had received a booster shot as of Nov. 17, according to the CDC.
Earlier this month, CDC director Rochelle Walensky, MD, said the agency had no plans to change its definition of fully vaccinated.
"The definition of 'fully vaccinated' is one dose of the Johnson & Johnson vaccine and two doses of the either Pfizer vaccine or the Moderna vaccine, and we're not examining changing that definition anytime at this point," Dr. Walensky said during a Nov. 3 White House COVID-19 briefing.
However, New Mexico Gov. Michelle Grisham said in her state, where at least 29 percent of confirmed cases over the last four weeks were among vaccinated people, that could change.
"We know vaccinations are the most effective tool to both blunting the spread of the virus and to protecting yourself and our families," Ms. Grisham said during a Nov. 17 virtual news conference, The Hill reports. "So we are analyzing what we can do to create those incentives — and potentially mandates — for making sure that people are fully vaccinated, which means three vaccines."
Real-world studies from Israel indicate boosters lower people's chance of breakthrough COVID-19 infection and severe illness. Data showed a third dose of Pfizer's vaccine in people ages 60 and older reduced the risk of infection by 86 percent and the risk of severe disease by 92 percent.
For Pfizer and Moderna recipients, people in the following groups are eligible for boosters at least six months after their last dose, according to the CDC: 65 years or older, adults in long-term care facilities, adults with underlying medical conditions, and adults who work or live in high-risk settings. For Johnson & Johnson recipients, all adults were eligible for a booster at least two months after their initial dose.
In addition to New Mexico, several other cities and states including Colorado, California and New York City have expanded booster eligibility to all adults in recent weeks.
Both Moderna and Pfizer have asked the FDA to approve boosters for all adults. As of the morning of Nov. 18, the FDA had not yet made a decision on either of the drugmakers' requests.