Amid COVID surge, experts look for ways to stretch vaccine supplies: The case for postponing the second shot

Andrew Romano
·West Coast Correspondent
·8 min read

America's COVID-19 vaccine rollout is going a lot slower than expected — so slow, in fact, that leading scientists are starting to debate whether authorities should take the drastic step of stretching available supplies to twice as many people by delaying the second of two doses or cutting each dose in half.

Their fear is that America’s vaccine distribution system is too sluggish to keep up with — let alone halt — a raging pandemic increasingly driven by new, more transmissible variants.

So far only 4.6 million Americans have gotten vaccinated, according to the Centers for Disease Control and Prevention, far short of the goal federal officials set to give at least 20 million people their first shot before the end of December, and nowhere near the 100 million doses in 2020 initially promised by the Trump Administration.

If vaccinations were to continue at the current pace, according to an NBC News analysis, it would take almost 10 years to inoculate enough Americans to get the pandemic under control.

With more than 2,500 Americans succumbing to COVID-19 daily — and no end in sight — the U.S. can’t afford to wait until 2022, let alone 2031. And so as coronavirus cases show signs of surging (yet again) after weeks of holiday gatherings, experts inside and outside the government are beginning to consider the idea of divvying up doses differently to get more shots into more arms as fast as our cumbersome infrastructure will allow.

It’s a complex, controversial issue, and there may be significant drawbacks. But in theory, at least, the logic of rethinking the authorized dosage regimen has a certain appeal.

The approach that has gotten the most attention is to delay administering second doses until supply catches up. In their clinical trials, Pfizer and Moderna tested two 100-microgram doses spaced three weeks (Pfizer) or four weeks (Moderna) apart. Both found that regimen to be safe and about 95 percent effective in preventing disease.

Yet both companies also reported that by the time participants showed up for their second shot, their first shot was already providing them with a high level of immunity. In Moderna’s case, the first (or “primer”) shot appeared to be 92.1 percent efficacious in preventing COVID-19 after two weeks, well before volunteers received their “booster” injection on Day 28. Pfizer’s results suggested similar protection — higher than 80 percent — after 10 to 12 days.

Neither the Pfizer nor the Moderna trial was designed to study the effectiveness of a single dose, so it’s unclear how long this immune protection would last, or at what level. But in real life, booster shots are often administered months or years after the initial primer; a three- or four-week interval isn’t set in stone.

So should America continue to act like it is? The federal government said Monday that it had delivered more than 15.4 million doses of the Pfizer and Moderna vaccines to states. But that’s only about half the federal stockpile; right now, Washington is holding the other half in reserve to ensure that there are enough booster shots to go around in 21 to 28 days.

The question then becomes whether it makes more sense to use a stockpile of roughly 30 million shots to produce 95 percent protection in 15 million Americans over the next month — or use that same stockpile to produce something like 85 percent protection in twice as many people in half the time.

The United Kingdom, Denmark and several Canadian provinces have already decided to delay second doses (to 12 weeks in the U.K. and six weeks in Denmark). Belgium, Germany and Ireland are mulling a similar shakeup.

Meanwhile, more and more top U.S. scientists are saying that what might be preferable in a perfect world — like strictly adhering to the initial vaccination schedule — could be counterproductive in the depths of spiraling pandemic, particularly when a new variant of the virus that’s 50 percent more transmissible is already spreading.

“Given the enhanced transmission variants on the rise, we need a modified strategy,” leading Yale immunologist Akiko Iwasaki tweeted Friday. “Unfortunately, the vaccine roll-out is much slower than we had expected. This means that even the vulnerable have to wait for months to get their 2 shot vaccines.”

Iwasaki went on to note that “a mutant virus with 50% ⬆ in transmission kills a lot more people than a mutant with 50% ⬆ in lethality”; viruses spread exponentially, and a small percentage of a very big number can easily be much bigger than a big percentage of a small number.

A healthcare worker with the Florida Department of Health in Broward prepares to administer a COVID-19 vaccine at a drive-thru vaccination site at Vista View Park on January 04, 2021 in Davie, Florida. (Joe Raedle/Getty Images)
A healthcare worker with the Florida Department of Health in Broward prepares to administer a COVID-19 vaccine at a drive-thru vaccination site at Vista View Park on January 04, 2021 in Davie, Florida. (Joe Raedle/Getty Images)

And so while “I am still a proponent of 2 dose vaccine,” Iwasaki concluded, the situation in the U.S. is so dire that “we can delay the 2nd dose until more vaccines become available,” adding that a “booster after a few months might be okay.”

Writing Sunday in the Washington Post, Robert M. Wachter, chair of the department of medicine at the University of California at San Francisco, and Ashish K. Jha, dean of the Brown University School of Public Health, agreed.

“Until recently, we supported the strict vaccine regimen, requiring two doses within a month,” they explained. But “between 50,000 and 100,000 Americans will die of covid-19 this month alone. Giving 100 million people — particularly those at high risk — a single shot that is 80 to 90 percent effective will save far more lives than giving 50 million people two shots that are 95 percent effective. It’s what we should do.”

Meanwhile, President-elect Joe Biden’s team thinks the idea is worth exploring. “The data from Pfizer — the amount of protection you got from a single dose — was pretty impressive,” Dr. Zeke Emanuel, a member of Biden’s COVID-19 advisory board, told Yahoo News. “It is something that has to be considered: how to stretch this absolutely scarce resource.”

Other experts remain skeptical. Some say that it would be irresponsible to delay a second dose until studies explicitly prove that protection from the first dose lasts longer than 28 days. Some worry that it would be unethical to tell those who already accepted their first shot — with the promise of a second to follow at three to four weeks — that they have to wait. Some fear that delaying an immunity-boosting second dose might give the virus more opportunity to multiply and mutate in partly protected people. And some believe that changing course based on untested extrapolations from limited data would further undermine fragile public trust in these already contentious vaccines.

For the record, Dr. Anthony Fauci, America’s top infectious disease expert, is not a fan of following in the U.K.’s footsteps and altering the dosage schedule. “I would not be in favor of that,” Dr. Fauci told CNN Friday. “We’re going to keep doing what we’re doing.”

But postponing the second shot might not be the only way to stretch America’s vaccine supply. Authorities are also considering halving the volume of vaccine in each dose, effectively doubling the amount of available doses. On Sunday, Moncef Slaoui, the head of America’s Operation Warp Speed vaccine effort, told CBS that participants in Moderna’s clinical trials between the ages of 18 and 55 who received two half-doses of 50 micrograms each produced an “identical immune response” to those who received two full 100-microgram doses.

“Injecting half the volume” into adults under 55 might constitute “a more responsible approach that will be based on facts and data to immunize more people,” Slaoui said. The U.S. Food and Drug Administration and Moderna are now “in discussions” about implementing and “accelerating” this regimen on a more widespread scale, he added.

It remains to be seen what will become of those discussions. It also remains to be seen whether vaccine distribution itself will accelerate in the new year — a necessary part of getting more people inoculated, however the doses are sized or scheduled.

Setting aside the federal stockpile of second doses, only about 30 percent of the first doses delivered to the states have actually been injected into living, breathing Americans. That means more than 10 million unused doses are just sitting there, waiting to be used — the result, experts say, of the Trump Administration’s decision to pass responsibility for vaccine distribution onto individual state health departments stretched thin by the pandemic, with little in the way of federal coordination or support. The new COVID-19 relief bill includes an additional $7 billion for state vaccination efforts, which should help, and the incoming Biden Administration has pledged to take a more hands-on approach.

Dr. Melisha Cumberland is given the the second dose of the Pfizer/BioNTech vaccine twenty-one days after receiving the first shot from RN Valerie Massaro of Hartford HealthCare, at the Hartford Convention Center in Hartford, Connecticut on January 4, 2021.(Joseph Prezioso/AFP via Getty Images)
Dr. Melisha Cumberland is given the the second dose of the Pfizer/BioNTech vaccine twenty-one days after receiving the first shot from RN Valerie Massaro of Hartford HealthCare, at the Hartford Convention Center in Hartford, Connecticut on January 4, 2021.(Joseph Prezioso/AFP via Getty Images)

But so far America has only vaccinated 1.38 percent of its population. Israel, in contrast, has vaccinated more than 14 percent. If the U.S. rollout continues to falter while cases, hospitalizations and deaths continue to soar — and scarier variants become dominant — impatient Americans may demand that leaders start to think outside the box.

“We seemingly gain a LOT from delaying (for some) the second shot by a short interval (perhaps just a few weeks),” Yale health-policy expert Howard Forman tweeted Saturday. “The risk to ‘reserving’ vast numbers of doses while rampant spread occurs seems HIGHER than the alternative. Let's put logic & science ahead of dogma.”

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