A new study shows the Pfizer-BioNTech vaccine remains 90% effective at preventing COVID-19 hospitalizations for up to six months after being fully vaccinated, even with the more transmissible delta variant and without a booster shot.
But the same study pointed out that the vaccine’s effectiveness does wane when it comes to acquiring a COVID-19 infection. Specifically, effectiveness was measured at 47% after five months of people receiving the two-dose vaccine, according to the study.
The Pfizer-funded study was published in "The Lancet" Monday. From December 2020 to August 2021, researchers studied and analyzed more than 3.4 million health records from people 12 years and older at Kaiser Permanente Southern California who were fully vaccinated with the Pfizer-BioNTech vaccine.
"Our results reiterate in a real-world US setting that vaccination with BNT162b2 [Pfizer-BioNTech vaccine] remains an essential tool for preventing COVID-19, especially COVID-19-associated hospital admissions, caused by all current variants of concern," the study’s authors said.
Researchers said they conducted the study to see how the Pfizer-BioNTech vaccine is holding up against the multiple circulating COVID-19 variants.
Pfizer-BioNTech started referring to its COVID-19 vaccine by its brand name Comirnaty after the U.S. Food and Drug Administration gave the shot its full approval in August. The proposed generic name for Comirnaty is tozinameran.
In September, the U.S. Food and Drug Administration authorized a third booster shot of the vaccine for Americans who are 65 and older, younger adults with underlying health conditions and those in jobs that put them at high risk for COVID-19. Under the FDA authorization, vaccinated Americans are eligible for the third dose six months after receiving their second Pfizer shot.
The FDA is convening its outside panel of advisers next week to review booster data from both Johnson & Johnson and Moderna and their vaccines.
According to the U.S. Centers for Disease Control and Prevention, 65.5% of Americans 12 years and older are fully vaccinated. An estimated 70 million eligible Americans remain unvaccinated, providing kindling for the delta variant.
The U.S. reached its latest heartbreaking pandemic milestone last week, eclipsing 700,000 deaths from COVID-19 just as the surge from the delta variant is starting to slow down and give overwhelmed hospitals some relief.
Nationwide, the number of people now in the hospital with COVID-19 has fallen to somewhere around 75,000 from over 93,000 in early September. New cases are on the downswing at about 112,000 per day on average, a drop of about one-third over the past 2 1/2 weeks.
Deaths, too, appear to be declining, averaging about 1,900 a day versus more than 2,000 about a week ago.
The easing of the summer surge has been attributed to more mask-wearing and more people getting vaccinated. The decrease in case numbers could also be due to the virus having burned through susceptible people and running out of fuel in some places.
But health officials and hospitals are bracing for another potential surge over the winter months.
Dr. Anthony Fauci, the government’s top infectious disease specialist, warned on Friday that some may see the encouraging trends as a reason to remain unvaccinated.
"It’s good news we’re starting to see the curves" coming down, he said. "That is not an excuse to walk away from the issue of needing to get vaccinated."
The Associated Press contributed to this report. This story was reported from Los Angeles.