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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.

  • “Other countries have already employed the delayed-dose strategy, with varying results.”

    Except you don’t mention a single piece of evidence to suggest that it doesn’t work. The UK has done it and gotten outstanding results despite the total dominance of B.1.1.7 in the country.

    Just look at the evidence. At the peak the UK was seeing 1,250 deaths per day on average. As at 2nd April the 7 day average is now 43 (!) per day and PLUMMETING I.e. 97% reduction in deaths.

    The US is at 875 per day on average as at 2nd April vs a peak of 3,459. I.e. only 74% reduction and NOT falling at anywhere near the rate of the UK.

    This is despite the U.S. having access to the two most efficacious approved vaccines globally.

    The strategy of sticking with 2nd doses only 3-4 weeks out and leaving tens of millions unvaccinated for many months is clearly killing TENS of THOUSANDS of additional people who did not need to die.

    Stephen Hahn may find the approach “concerning” but I’d say that is because he represents an institution that has become so risk adverse it cannot see the forest for the trees in terms of maximising the benefit to the public of vaccine rollouts.

    Anybody with even a modicum of understanding of statistics and exponential growth factors can see that the evidence is OVERWHELMINGLY in favour of accelerating FIRST DOSES NOW to stop many tens of thousands of completely preventable deaths and HUNDREDS and HUNDREDS of thousands of cases of long COVID and other serious impacts to the health of US citizens.

  • The Kaiser Family Foundation has been studying the public’s concerns about COVID-19 vaccination. For those most likely to get vaccinated, one of their largest concerns is that they won’t receive their second dose in 3-4 weeks (“on time”). These individuals may forego vaccination entirely, especially the healthy and young, if they’re uncomfortable with the delay in second dose.

  • If we declared a one month moratorium on second doses and only did first doses for that one month we’d go from about ~100MM w/ their first shot to ~200MM people with their first dose by about the end of that month. At that point I am guessing due to hesitancy the vaccine supply made everyday would outpace the number of people each day willing to get a first shot. We could then go back to giving second shots per the recommended intervals as much as possible.

    On the other hand if we maintain the current interval between shots we should be at the same ~200MM people with first shots in about ~2 months.

    Arguably there’s a benefit to it (~1 month) but it’s very late to change things. I don’t see them doing it at this point.

    Alternatively (per Zeke Emmanuel) if they were just focused on doing something to get to ~150MM people with first dose ASAP they could have a shorter moratorium on second doses of about ~17 days then revert to normal

  • One note about this is this article questions the effectiveness of the vaccine. We have data saying they are effective and then all we have to do is look at Israel. Interesting article that really sums up why a vaccine passport would be impractical and possibly unconstitutional. Not the least of which is it could turn vaccinating people into a political issue. I’m for vaccinating people – just not through force

    Resistance from health experts and business owners could doom ‘vaccine passports’ even before they launch

  • Since more and more Republicans refuse to get vaccinated (about 50% and growing according to a poll over two weeks ago), that means that about 25% of the adult population is refusing to get vaccinated; so about 160 million double doses or 80 million single doses won’t be needed – Missouri is a case in point red state with a huge surplus of vaccine and no one showing up a vaccination sites.

    • That is not entirely true – yes, there are hesitant people but they can be convinced (not all but we don’t need all). I’m Conservative and I strongly believing in getting the vaccine. I actually got it this past weekend. Even if I don’t get really sick by me getting the virus, someone else could. That said, you can’t go by polls for anything. I’ve seen polls that say vaccine hesitancy has dropped dramatically because people see that they are safe and effective from other people getting them. The reason though for the vaccines is to return to normal.

      Why does this have to be such a political issue though? The simple reason rural people are more resistant is because they haven’t had the same experiences as people in cities have. They haven’t necessarily known someone that’s gotten seriously sick or died. We need to persuade people to get the vaccine – not force them like with a vaccine passport.

      Even if you could get through all the logistical issues of setting it up, getting everyone to use them, and all the legal challenges (such as people having freedom of movement), most of the country will likely be vaccinated by then because any vaccine passport would be temporary.

      Also, this isn’t communist China were you have to show papers to move about. It’s just I’m fine with them for international travel, schools requiring children at some point to get vaccinated, and maybe employers but restricting freedom of movement I think is just too far. You could say we do it for terrorists and things like that, but that’s not anywhere near the same as saying you can’t live your life if you’re not vaccinated.

      Further, if you had a vaccine passport – the focus would instantly change from vaccinating people to a debate over the passports which is the last thing we need.

      Resistance from health experts and business owners could doom ‘vaccine passports’ even before they launch

  • Have any of these experts bothered to account in their recommendations for the herd mentality out in the streets?

    My wife and I went to a very uncrowded beach (where we still wore our masks around people social distance by the length of a football field) about an hour from our home this morning (and less than an hour north of our medical shrines in Boston). Twixt home and beach, we passed strip mall after strip mall filled with cars. Restaurant parking lots full, with signs proclaiming “INDOOR DINING”. Shoppers carrying bags in and out of stores. Ah, but they all wore masks, so it was OK, right?

    But don’t take my anecdotal word for it. Check this out from BMJ:

    I can’t imagine anything more irresponsible at this point than to tell people it’s OK to delay the second vaccine without saying that doing requires adherence to the guidelines they’ve been ignoring since Thanksgiving.

    Any you wonder why they don’t listen to you? Seriously?

    • I may be failing to understand your Comment, but it seems to me you are not being very logical.
      If you have a disease which is being spread rapidly – I think you would want the maximum number of people made immune. I have 100 vaccine doses – I can give them out to 100 people, and in two weeks I have 80 immune people. OR, I can give them out to 50 people – and in two weeks have 40 immune people =and in 3 or 4 more weeks – have 45 immune people. Not 45 more – 45 total – 5 or 6 weeks later I have 45 vs. 80 – and we are not even counting the fact I got the my 80 people immune in two weeks, whereas under the other protocol I got only got my 45 after the more than twice as long.
      Consider this – I want to look at days of vulnerability to infection – because when people catch a virus, they catch it on a day they were NOT immune.

      Compare the current Pfizer BioNTech protocols with the suggested “One dose now, 2nd dose 4 months later” protocol.

      We will have 100 people, and 100 doses of vaccine, in each protocol. We do know now when the people who do not get vaccine under current protocol will be able to get a dose = we wil assume they will have to wait 5 weeks, but it could be longer

      Current protocol –

      50 people are given their first dose. They are fully vulnerable for two weeks. Another 50 are given no vaccine for at least 5 weeks, could be longer.
      50 people with no vaccine x 5 weeks each = 250 person weeks of vulnerability]

    • Under proposed new protocol, I have 100 people I vaccinate with one dose – and I have 20 people who are vulnerable for 5 weeks = 100 person weeks of vulnerability.
      Note, this assumes the 2nd dose is given to all non-vaccinated people immediately after the 5 weeks ends- so everyone is full vaccinated – but the new protocol anticipates there will not be enough vaccine for months to give everyone the 2nd shot – so, suppose everyone waits another month?
      The current protocol group have 55 unprotected people x 4 weeks – another 220 person weeks of vulnerability – the new protocol group have the same 20 unprotected people for another 4 week= 80 person weeks of vulnerability.
      I am not a virologist and this may be an oversimplification, but unless immunity plummets for those given one dose compared to those given two, it seems the new protocol is a lot more likely to stop the epidemic.

  • Clinical trials tell us what is effective. We should not substitute the opinions of non-scientists for clinical trial results. We should administer the vaccines using the schedules and doses that were tested in the clinical trials. Otherwise, we are just using wishful thinking.

    • Please do not be offended but I think your Comment is wrong multiple ways.
      1. “Clinical Trials tell us what is effective” = the figure of 80% efficacy two weeks after one shot came from clinical trial data. At least the proponents of the protocol change say so, if they are wrong that, is a debate over the meaning of results, not a matter of ignoring clinical trial data.
      2. “We should not substitute the opinions of non-scientists for clinical trial data” – the politicians pushing for the change are not scientists – some are MDs – but a LOT of scientists believe in it and have advocated for it.
      3. “We should administer the vaccines using the schedules and doses that were testing in the clinical trials. Otherwise, we are just using wishful thinking” – well, NO, there is a LOT of data to support the change – I am not saying it is right, but it certainly is not just “wishful thinking” that is very dismissive of a lot of very smart people.

    • Randomised clinical trials are just one form of data.

      The REAL WORLD MASSIVE OBSERVATIONAL STUDY in the UK is frankly FAR better evidence of the effectiveness of this strategy than a 30,000 person RCT could ever be (30+ MILLION people dosed 12 weeks apart for BOTH Pfizer and Astrazeneca).

      Infection and death rates have plummeted WAY faster than the US (let alone the debacle that is the EU) and there is no signs that the elderly are not protected.

  • Lev, one of the better pieces I have read on STAT. Nicely done, in that you properly present both sides of the argument.

    I am not a huge fan of Zeke, who I think has a disturbing eugenicist streak, but his is a plausible argument. However, going to one dose approach may prolong lockdown requirements because our mentally challenged politicians may think, “Hey it can still spread, even with one dose so hide people hide!!!” That would be counterproductive.

    And for heavens sake, can we get rid of the slippery and useless phrase “spiking cases?’ What the heck is a “spike?” What percentage over what time period constitutes a “spike?” It’s a useless word.

    Anyway, by the time they get to a decision, we may have reached herd immunity or very close to it.

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