(CNN) – The United States remains steadfast in its strategy of administering two doses of the Modern and Pfizer / BioNTech Covid-19 vaccines a few weeks apart. However, the idea of expanding the offer by dispensing only one dose has not faded.
Trump administration general surgeon Dr. Jerome Adams said in a tweeted on Tuesdayand that the good protection available with a single shot “is better than great protection for a few.”
He later clarified with a second tweet that he did not recommend that it be 100% of the way forward, but that it was worth “giving the states the flexibility to try it.”
Although 80.5 million doses of vaccine have been administered in the United States and the Johnson & Johnson single-dose vaccine is on offer in the United States, demand still far exceeds the number of vaccines available.
This has not influenced vaccine manufacturers, the U.S. Food and Drug Administration or the CDC toward the single dose to cover more people sooner.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN’s Erin Burnett on Wednesday that Adams’ tweets did not take into account the impact of virus variants, which they can decrease the amount of protection against vaccines.
“First of all, I love Jerome Adams. He’s really a fantastic guy. We worked so well together during the Trump administration, “Fauci said.” I think that’s wrong with that. “
With just one dose, “you have a very low level. Good enough to protect, but if you reduce it by five, you stay on the protection letter. “
MRNA vaccines were authorized for use in the United States based on clinical trial data showing that two doses of vaccines taken a few weeks apart are approximately 95% effective in preventing symptomatic infection. Clinical trials for both vaccines show that the second dose gives a great boost to protective antibodies.
CDC guidelines continue to advise two doses of Pfizer and Moderna vaccines, and experts at the meeting of the CDC’s Advisory Committee on Immunization Practices (ACIP) said there is not enough scientific evidence to support a strategy for vaccination that would delay a second dose or eliminate it all together.
“Five studies have shown that postponing the second dose of mRNA may leave some people less protected from SARS-Cov-2 variants,” CDC Dr. Heather Scobie told the ACIP meeting.
Fauci told the Washington Post this week that there are “risks on both sides” of switching to a single dose or staying with both. Experts worry that a single-dose strategy could lead to more coronavirus variants and generate more doubts and confusion during an already complicated vaccine deployment.
“It simply came to our notice then [two shots] is that what you have to do … and then we say, “Wow, we’ve changed our minds”? “I think that would be a messaging challenge, at least.”
That’s not to say there won’t be any more dosage changes to come.
Worldwide, researchers are studying the effectiveness of single doses of mRNA vaccines. Meanwhile, the J&J vaccine, currently authorized as a single-dose vaccine, is also being tested in two doses to see if it will provide more protection.
Study simple doses
Some countries already use single-dose strategies as a way to expand supply and offer some protection to more people.
Since late December, the UK has not told people to skip the second shot, but has delayed the second doses of the Pfizer / BioNTech vaccine to prioritize the first doses. The delay meant that the interval between doses could be extended up to 12 weeks instead of about three.
In reaction to the change in vaccine schedule, Pfizer said then that it did not test its vaccine in this way.
“The Pfizer and BioNTech phase 3 study for the Covid-19 vaccine was designed to evaluate the safety and efficacy of the vaccine following a 21-day, separate dose schedule,” Pfizer said. “There is no data to show that protection after the first dose is maintained after 21 days.”
There has been some research to suggest that the Pfizer / BioNTech vaccine provides some protection after a dose.
Researchers at Israel’s largest hospital examined what happened after 7,000 employees were vaccinated with the first dose of the Pfizer / BioNTech vaccine. From the second to the fourth week after getting the first shot, symptomatic infection rates dropped by 85%.
However, it is not yet clear how long this protection would last. In addition, the study noted that vaccinated people were “younger and healthier” and may not reflect the wider population.
There is also some research suggesting that one dose may be enough for people with a previous infection. Two articles published last week in The Lancet found that just one dose of the Pfizer / BioNTech coronavirus vaccine can induce a strong enough immune response in people who have already had the coronavirus that could protect them from future infections. France has already recommended that people with infection previously receive only one dose.
And in a letter sent to the New England Journal of Medicine in February, Canadian researchers reviewed the documents Pfizer / BioNTech submitted for emergency use authorization last year and concluded that a single dose is still effective at least 90%.
“With such a protective first dose, the benefits of a scarce supply of vaccine could be maximized by deferring the second dose until at least one dose is offered to all members of the priority group,” they added.
But, they noted that it is still unclear how long the protection lasts with just one dose.
The-CNN-Wire
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