Fauci sets the direct record with one or two doses of Pfizer and Moderna vaccines

(CNN) – The United States is steadfast in its strategy of administering two doses of the Moderna and Pfizer / BioNTech Covid-19 vaccines a few weeks apart. Even so, the idea of ​​expanding the supply by dispensing only one dose has not disappeared.

The general surgeon of the Trump administration, Dr. Jerome Adams, said in a tweet on Tuesday that the good protection available with a shot “is better than great protection for some”.

He later clarified with a second tweet that he was not recommending that this be 100% the way to go, but that it was worth “giving states the flexibility to try it out”.

Although 80.5 million doses of vaccine have been administered in the United States and the Johnson & Johnson single dose vaccine is entering the US supply, demand still exceeds the number of vaccines available.

This did not influence vaccine manufacturers, the Food and Drug Administration or the CDC to switch to single doses to cover more people earlier.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN’s Erin Burnett on Wednesday that Adams’ tweets were not responsible for the impact of virus variants, which may decrease the amount of protection vaccines.

“First of all, I love Jerome Adams. He’s really an amazing guy. We worked very well together during the Trump administration, ”said Fauci. “I think he is wrong about that.”

When choosing just one dose, “you are at a very tenuous level. Good enough to offer protection, but if you decrease it by five times, you’re off the protection map. “

MRNA vaccines have been authorized for use in the United States based on clinical trial data showing that two doses of vaccines taken a few weeks apart are about 95% effective in preventing symptomatic infection. Clinical trials for both vaccines show that the second dose gives a boost to protective antibodies.

CDC guidelines continue to recommend two doses of the Pfizer and Moderna vaccines, and experts from the CDC’s Immunization Practices Advisory Committee (ACIP), meeting on Monday, said there was not enough scientific evidence to support a vaccination strategy that would delay a second dose or it would eliminate everything together.

“Five studies have shown that postponing the second dose of mRNA can make some people less protected against SARS-Cov-2 variants,” said Dr. Heather Scobie of the CDC at the ACIP meeting.

Fauci told The Washington Post this week that there are “risks on both sides” of switching to a single dose or taking both. Experts fear that a single dose strategy could lead to more variants of the coronavirus and create more doubts and confusion during the launch of an already complicated vaccine.

“We are telling people [two shots] is what you should do … and then we say, ‘Oops, we changed our minds’? ”Fauci said. “I think it would be a messaging challenge, to say the least.”

This does not mean that there will be no further dosage changes to come.

Worldwide, researchers are investigating 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.

Studying single doses

Some countries are already employing single dose strategies as a way to expand their supply and offer some protection to more people.

Since late December, the UK has not told people to skip the second dose, 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 around three.

In reaction to the change in the vaccination schedule, Pfizer said at the time that it did not test its vaccine in this way.

“The Phase 3 study by Pfizer and BioNTech for the Covid-19 vaccine was designed to assess the safety and efficacy of the vaccine after a 2-dose, 21-day schedule,” said Pfizer. “There is no data to show that protection after the first dose is maintained after 21 days.”

Some research suggests that the Pfizer / BioNTech vaccine provides some protection after a dose.

Researchers at Israel’s largest hospital observed 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 the first injection, rates of symptomatic infection fell by 85%.

However, it is not yet clear how long this protection would last. In addition, the study noted that people who were vaccinated were “younger and healthier” and may not reflect the general population.

There is also research to suggest that one dose may be sufficient 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 already had the coronavirus that could protect against future infections. France has already recommended that people previously infected receive only one dose.