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WASHINGTON — As Covid-19 cases spike and coronavirus variants continue to spread, the Biden administration is facing renewed calls to delay second vaccine doses and blanket more of the U.S. population with an initial shot.

Advocates of a strategy focused on first doses include Democratic and Republican senators, Trump administration surgeon general Jerome Adams, and at least four physicians or epidemiologists who advised President Biden on pandemic response issues prior to his inauguration, including the prominent surgeon and author Atul Gawande.


Despite the new advocacy, and its own warnings of “impending doom,” the Biden administration has given no indication it will budge. But the shift in opinion underscores the growing alarm at a possible fourth wave of U.S. Covid-19 cases — and frustration with the federal government’s lack of flexibility.

“We need to get 50 million more people vaccinated as fast as we can,” said Zeke Emanuel, the physician who served as a key Obama administration health adviser and sat on President Biden’s pandemic advisory board during the transition. “We could get there in the next two and a half or three weeks if we focus on giving everyone one dose. I think we’re missing another opportunity.”

Gawande wrote this week that the Biden administration should delay second vaccine doses until 12 weeks following the first dose, as opposed to the current three- or four-week interval. Two other members, Emanuel and Michael Osterholm, have argued for delaying second doses since February. A fourth, Céline Gounder, recently announced she was reconsidering her stance after months of vocally opposing the strategy.


The latest push comes as U.S. case rates have begun to tick upward, and as some states, including Michigan, have begun to experience a surge in hospitalizations reminiscent of July 2020 and January 2021. The U.S. has reported roughly 60,000 new cases per day for the last week, far below the country’s January peak but similar to last summer’s surge.

The Biden administration has stayed the course despite new evidence suggesting that even a single dose of the vaccines manufactured by Moderna or the Pfizer-BioNTech partnership is highly effective at reducing Covid-19 infections. Risk of infection, according to a recent study, falls by 80% two weeks after an initial shot. The figure increases to 90% two weeks after a second dose.

A growing number of public health experts have used the new data to argue that the strategy is clear-cut. In the short term, they contend, giving twice as many people 80% protection against the virus would do dramatically more to stop the spread than giving the current number 90% protection.

Other countries have already employed the delayed-dose strategy, with varying results. It has been highly successful in the United Kingdom, which has deployed the tactic with Pfizer-BioNTech’s and AstraZeneca’s vaccines, extending the interval between doses there to 12 weeks. Already, 47% of citizens have received at least one dose. Though only 7% of the population is fully vaccinated, daily case rates there have plummeted from roughly 55,000 in January to barely 5,000 today. In the U.S., by contrast, 31% of the population has received at least one shot and 18% are fully vaccinated.

“Britain is the best argument for a delayed second dose strategy,” Emanuel said. “They seem to have done it pretty successfully. Even with the B.117 variant …. their numbers are pretty remarkable.”

The vast majority of U.S. vaccinations to date have used two-dose vaccines, despite the February authorization of Johnson & Johnson’s single-dose immunization.

Last month, Canada, too, mandated a four-month gap between first and second doses of the Pfizer-BioNTech and Moderna vaccines, a move that has led to anger and frustration especially from the country’s seniors. Preliminary research, which has not yet been peer-reviewed, has shown the approach may be less effective for older people, whose immune response to the vaccines is typically weaker than in younger people.

Members of Congress who have advocated for the change include two Democratic senators, Chris Van Hollen (Md.) and Martin Heinrich (N.M), as well as a number of staunchly conservative Republican physicians, like Sen. Roger Marshall (Kan.) and Rep. Andy Harris (Md.).

“As a threat rises from new disease variants, we write to request your consideration of a new strategy to maximize the population receiving the COVID-19 vaccine in the near term,” Van Hollen and Heinrich wrote last month in a letter to Jeff Zients, the White House pandemic coordinator. “We encourage you to explore deploying existing second doses as first doses and rely on growing real-time inventory to cover future follow-on booster shots.”

In a separate letter, Republicans lawmakers urged the Biden administration to issue a new emergency authorization allowing health officials to give only a single dose of vaccines developed by Moderna and a Pfizer-BioNTech partnership “until all vulnerable and essential populations are inoculated, and more vaccine doses become available.”

Their calls, however, largely fell on deaf ears, particularly in February and early March, when U.S. case rates were sharply down from their peak of roughly 250,000 in January.

The shift would likely require a nod of approval from the Food and Drug Administration, which warned against deviating from the three- and four-week intervals in January, prior to Biden’s inauguration. In a statement, the agency’s former commissioner, Stephen Hahn, said he found proposals for delayed dosing strategies “concerning,” and that the agency continues to “strongly recommend that health care providers follow the FDA-authorized dosing schedule.”

Tony Fauci, the country’s chief infectious diseases researcher, has argued that there isn’t solid evidence to back a delayed-dose strategy. Even if an initial first dose gives good protection against Covid-19, he said at a recent White House briefing, it’s unclear how long that protection would last.

Beyond posing an unnecessary risk to individuals’ immunity, Fauci has also warned that pivoting midway through the vaccine rollout could send the message that there’s no need to return for a second shot, whether it’s three or 12 weeks after their first.

Fauci has also warned that delaying second doses could help foster the growth of “escape” variants, or strains of the SARS-CoV-2 virus that are more likely to evade existing vaccines’ protectiveness.

A paper published this week in Nature, however, argued the opposite: There is little evidence that so-called “dose-sparing” strategies help to select for escape variants. The math, its authors note, is simple.

“[If] individuals who receive half as much vaccine (one versus two doses, or half the quantity of antigen per dose) achieve more than half the protection from clinical infection of those given a full regimen, then spreading the vaccine among more individuals will produce greater reductions in the number of clinical infections,” they wrote.

  • Quoting the Nature article that “the math is simple” without scrutiny or challenge is problematic. The proposal is to removing protection from a higher-risk population to give it to a lower-risk population. So deaths and hospitalizations could easily increase if you did that, given that hospitalizations and deaths rise geometrically with age and comorbidities. Also, the “math” assumes that the demographic groups spreading the virus most vigorously will rush right in to get vaccinated along with everyone else. I’m not so sure about that. So the math looks complicated to me, with an answer that could tilt toward sticking with the current “second dose on time” practice.

  • This may be a bit too speculative and maybe flat out misinformed, but what if Dr. Fauci is against this because he has a personal fear, going beyond a purely logical analysis, of creating a “superbug” ?
    Dr. Fauci advocated for Gain of Function research, some of which was carried out at the Wuhan Institute of Virology. Some people believe this made a virus which was not dangerous to humans into a superbug. Does Dr. Fauci feel concerned this may have been what happened? Is that why he is so scared of creating hosts to grow more pathogenic variants?
    I do not know. I do find it kind of odd that a man who took on other scientists to lobby hard for Gain of Function research, when others thought it was too dangerous, is now against a seemingly mild deviation from protocol, even though it seems to be working very well in the UK. He was not very risk adverse before, but now seems to be scared by the mere possibility of a problem, completely unproven, and, rationally, no matter what we do, the virus has billions of people to infect outside the US, for the next year or so.
    I think we have to consider the possibility he has some fear he helped create this pandemic, and his emotions about that are distorting his thinking.

    • I take what is currently being “advised” by Dr Fauci and the CDC with a big grain of salt. Too many pronouncements then walk backs tell me they are either lacking in knowledge or influenced by politics or market share. Remember it was Fauci and the CDC who said the public does not need a mask, now they recommend 2. Personally I think it is time for Dr Fauci to retire. No one individual should dominate any of our health research institutions as long as he has. I too question where some of his decisions come from, whether it’s due to inside info on Gain of Function research or his own gains. Heading up NIAID is a pretty powerful position where one can influence where grant money goes. I don’t believe mass vaccination is the way out of this pandemic. Having a range of therapeutic that enable us to treat the virus so it does not make people sick or critically ill should have been our top priority. Why are we only just now seeing Pfizer and Merck clinical trials of protease inhibitors to treat CV19? The timing after the vaccine roll out makes no sense unless you look at it through a monetary lens. If Fauci was doing his job free of conflict or personal bias he might have pushed therapeutics harder before EUA vaccines. Fauci has had many missteps over the past year. The fact that people refer to him as America’s top doc says a lot more about us than him.

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