is preparing to seek approval in the United States
for a third dose of its COVID-19 vaccine, saying Thursday that another shot within the next 12 months could significantly boost immunity and possibly help ward off the latest worisome coronavirus
According to research
from multiple countries, the Pfizer shot and other widely used COVID-19 vaccines
provide strong protection against the highly contagious delta variant
, which is rapidly spreading around the world and is now responsible for the majority of new infections in the United States.
Most vaccines require two doses to develop high levels of virus-fighting antibodies against all versions of the coronavirus, not just the delta variant, and most of the world is still desperate for those first protective doses as the pandemic
However, because antibodies naturally wane over time, research is being conducted to determine whether and when boosters are required.
Dr. Mikael Dolsten of Pfizer told The Associated Press
on Thursday that preliminary data from the company's booster study indicate that people
's antibody levels increase five- to tenfold after a third dose, compared to their second dose months earlier.
Pfizer intends to apply to the Food and Drug Administration
for emergency approval of a third dose in August, he says.
Dolsten cited data from the United Kingdom
indicating that the Pfizer vaccine “neutralizes the delta variant very well.” The assumption, he said, is that when antibodies drop low enough, the delta virus can cause a mild infection before the immune system kicks in.
However, FDA approval would only be the first step; it would not automatically mean that Americans would be offered boosters, cautioned Dr. William Schaffner, a vaccine expert at Vanderbilt University
Medical Center. Instead, public health
officials would have to decide whether they are truly necessary, especially given that millions of people lack protection.
“The vaccines were designed to keep us out of the hospital
,” he said, and they continue to do so despite the more contagious delta variant. Giving another dose would be “a huge effort while we are currently striving to get people the first dose,” he added.
Currently, only about 48% of the U.S. population is fully vaccinated — and some parts of the country have far lower immunization rates, where the delta variant is on the rise. Dr. Rochelle Walensky
, director of the Centers for Disease Control and Prevention
, said on Thursday that this is leading to “two truths” — highly immunized swaths of America are returning to normal, while hospitalizations are increasing.
“This rapid rise is troubling,” she said, noting that just a few weeks ago, the delta variant accounted for just over a quarter of new cases in the United States, but it now accounts for just over 50% — and as much as 80% in some places, such as the Midwest.
Additionally, researchers from France
's Pasteur Institute reported new evidence that full vaccination
is critical on Thursday.
Blood from several dozen people given the Pfizer or AstraZeneca vaccines “barely inhibited” the delta variant in laboratory tests, the team reported in the journal Nature
, but weeks later, nearly all had what researchers deemed an immune boost strong enough to neutralize the delta variant — even if it was slightly less potent than against earlier versions.
The French researchers also tested unvaccinated people who had survived a bout of the coronavirus and discovered that their antibodies were four times less potent against the new mutant. However, a single vaccine dose dramatically increased their antibody levels, sparking cross-protection against the delta variant and two other mutants, the study found.
The lab experiments add to real-world evidence that the delta variant's mutations aren't evading the vaccines most commonly used in Western countries, but they also highlight the importance of immunizing more people before the virus evolves even further.
Two doses of the Pfizer vaccine, for example, are 96% protective against hospitalization with the delta variant and 88% effective against symptomatic infection, according to British
researchers, who were echoed by Canadian researchers last weekend, while a report from Israel suggested protection against mild delta infection may have dropped to 64%.
maintains that fully vaccinated people do not need to wear masks
in areas where the delta variant is on the rise. Even before the delta variant, vaccines weren't perfect, but the best evidence suggests that if vaccinated people get the coronavirus, they will have much milder cases.
“Let me emphasize, if you were vaccinated, you have a very high degree of protection,” said Dr. Anthony Fauci
, the top infectious disease expert in the United States, on Thursday.
In the United States, case rates have been rising for weeks, and hospitalizations have begun to rise, rising 7% from the previous seven-day average, Walensky told reporters Thursday, but deaths have remained low on average, which some experts believe is due, at least in part, to high vaccination rates among people 65 and older, who are among the most vulnerable to severe disease.
This story was written by Associated Press writer
The Howard Hughes Medical Institute's Department of Science Education
provides funding to the Associated Press Health and Science Department, but the AP is solely responsible for all content.