Some medical experts say one-shot regimen for Pfizer, Moderna COVID-19 vaccines not enough

Following the recent emergency approval by U.S. regulators for a coronavirus vaccine from Johnson & Johnson which contains a single-dose regimen, some medical experts are saying one dose isn’t enough from the other two approved vaccines in the U.S. - Pfizer and Moderna - for full protection against COVID-19. 

"You would be flying blind to just use one dose," said one senior scientist and adviser to President Joe Biden told the Wall Street Journal. "If you’re going to do something else other than follow the studies shown to the FDA, show me that this one-shot effect is durable."

The comment comes as some lawmakers and health officials have urged that the U.S. needs to shift to a single-dose regimen for all coronavirus vaccines.

Acting Health and Human Services Secretary Norris Cochran along with seven physician members of Congress wrote in a March 2 letter urging the department to "consider issuing a revised emergency use authorization as soon as possible" that might lead to single-dose use of the Pfizer and Moderna vaccines."

RELATED: Pfizer says lab test indicates diminished antibody response by its COVID-19 vaccine to South Africa variant

"As you know, vaccine distribution and administration has been met with challenges across the country," according to the letter. "Evaluating all available clinical data now would allow states to more widely administer a single dose of both the Pfizer-BioNTech and Moderna mRNA vaccines until all vulnerable and essential populations are inoculated, and more vaccine doses become available."

Another senior U.S. government doctor told the Wall Street Journal that the durability of two doses will be more effective against the increasingly concerning coronavirus mutations that are continuing to spread throughout the world. 

Some studies have shown that some of these mutations are less impacted by some of the vaccines currently in circulation. 

One laboratory study from Pfizer suggested that the company’s current COVID-19 vaccine may generate a significantly less robust antibody response against the South Africa variant of the coronavirus. 

According to the in vitro study published in the New England Journal of Medicine (NEJM), lab results "indicated a reduction in neutralization," of the virus.

In the Pfizer study on the South Africa variant, researchers analyzed blood from people who had taken the Pfizer coronavirus vaccine and identified a two-thirds reduction in the level of neutralizing COVID-19 antibodies.
This was compared with the most common variant of the virus prevalent in the U.S.
"It is unclear what effect a reduction in neutralization by approximately two-thirds would have on BNT162b2-elicited protection from Covid-19 caused by the B.1.351 lineage of SARS-CoV-2," researchers wrote.

Despite the results of the in vitro lab test, the company said that there is still no clinical evidence from human trials that the South African mutation reduces the overall protection of the vaccine.

J&J’s vaccine protects against the worst effects of COVID-19 after one shot, and it can be stored up to three months at refrigerator temperatures, making it easier to handle than the previous vaccines, which must be frozen.

The FDA advisory panel’s chairman, Arnold Monto told the Wall Street Journal that the two-shot regimen is the best course of action for the Pfizer and Moderna vaccines.

"We’ve got information on a two-dose strategy," Dr. Monto told WSJ. "We need high antibody levels from those doses to deal with the variants."

The two-dose Pfizer and Moderna shots were found to be about 95% effective against symptomatic COVID-19. The numbers from J&J’s study are not that high, but it’s not an apples-to-apples comparison. One dose of the J&J vaccine was 85% protective against the most severe COVID-19. After adding in moderate cases, the total effectiveness dropped to about 66%.

Meanwhile, the U.S. Centers for Disease Control and Prevention said on Monday that fully vaccinated Americans can gather with other vaccinated people indoors without wearing a mask or social distancing.

The recommendations also say that vaccinated people can come together in the same way — in a single household — with people considered at low-risk for severe diseases, such as in the case of vaccinated grandparents visiting healthy children and grandchildren.

The Associated Press contributed to this story.