President Biden on Tuesday announced he's moving up the deadline for states to make all American adults eligible for Covid-19 vaccines by two weeks from May 1 to April 19.

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Biden sets new target for all adults to be eligible for Covid-19 vaccine

Last month during his first primetime address, Biden said his administration would direct state, local, and tribal governments to make all American adults eligible for Covid-19 vaccines by May 1. However, Biden on Tuesday moved up that deadline to April 19.

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A White House official said Biden updated his deadline because states have been ramping up their vaccination programs faster than expected after seeing increases in vaccine shipments. Biden last week said at least 90% of American adults would be eligible for Covid-19 vaccines by April 19.

Biden's revised deadline comes as America's vaccination campaign has gained momentum. White House officials on Monday said the United States is administering an average of 3.1 million doses per day over a seven-day period—up from an average of less than 1 million in January.

According to CDC data, the federal government has shipped 219.2 million vaccine doses to states, territories, and federal agencies since last year. White House press secretary Jen Psaki during her daily briefing on Tuesday said states will receive more than 28 million doses of Covid-19 vaccines this week.

According to the New York Times, many states already have expanded their vaccine eligibility because of a recent increase in vaccine supply. For example, Maryland Gov. Larry Hogan (R) on Monday said all state residents ages 16 and older would be eligible for a Covid-19 vaccine at the state's mass vaccination sites starting Tuesday and at any vaccination site in the state beginning April 19.

Experts say demand may soon outpace supply

However, some experts have said the demand for vaccines may soon outpace America's supply as vaccine eligibility expands throughout the United States.

Jason Schwartz, assistant professor of health policy at Yale University and a member of the Connecticut vaccine advisory committee, said, "Expanding to open eligibility will lead to that initial rush of eligible individuals who have been champing at the bit to get the vaccines, navigating the system, signing on the minute they're eligible."

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Similarly, Robert Wachter, professor and chair of the University of California-San Francisco Department of Medicine, said he expects scheduling a vaccine appointment as eligibility expands will be comparable to scoring Elvis tickets in the 1950s.

Prashant Yadav, a senior fellow at the Center for Global Development, said, "The bigger challenge still is how to manage the deluge of potential (vaccine recipients) who will become eligible on April 19 with a patchwork of appointment-scheduling systems across states, counties, and vaccination providers—systems which don't necessarily talk to each other." Yadav said he expects Americans may become frustrated when they log on to book an appointment and find only a limited number of slots available.

The situation will likely evolve by May, however. Schwartz, Wachter, and other experts have said they expect vaccine supply will eventually overtake the country's demand—with the total vaccine production from Pfizer/BioNTech, Moderna, and Johnson & Johnson reaching nearly 4 million doses a day.

"Very quickly, really in a matter of weeks after each state moves to open eligibility, we're going to shift to a very different phase in the vaccine rollout where we will have plenty of doses available," Schwartz said.

Kelly Moore, an adjunct associate professor of health policy at Vanderbilt University and deputy director of the Immunization Action Coalition, said she expects America's vaccine campaign to become more effective as vaccine supply increases and eligibility restrictions are lifted. 

"It's going to be far more efficient to deliver vaccine doses once immunizers can vaccinate anyone who comes along without screening for priority group," she said. "Prioritization was always meant to be limited to a brief time when vaccine supplies were scarce. While these efforts can help get early vaccine doses to those who need it most, it also slows down the process of vaccinating the population. Now that supply is not scarce, we need to open up and vaccinate at full throttle everywhere."

Once the country's vaccine supply exceeds demand, experts said the focus of America's vaccination campaign will shift to reaching vaccine-hesitant populations (Treisman, NPR, 4/6; Superville/Jaffe, Associated Press, 4/6; Pietsch et al., New York Times, 4/6; Weixel, The Hill, 4/5; Sullivan, The Hill, 4/6; Ortiz, USA Today, 4/6; Holcombe, CNN, 4/7).