Pfizer-BioNTech’s COVID-19 vaccine remains effective in preventing hospitalizations for at least six months, according to a new study.
Researchers at Kaiser Permanente Southern California (KPSC) collected data from the company’s healthcare network to find out how often fully vaccinated people were either tested positive for the virus or hospitalized because of it.
They found that the Pfizer vaccine was 90 percent effective at preventing hospitalizations for the first six months after being fully immunized.
The existing variants also appear to have little ability to bypass vaccines, including the highly transmissible Delta variant, which is now responsible for almost all cases in the United States.
However, the vaccine’s effectiveness in preventing infection declines dramatically over time, dropping to 47% after five months.
Previous studies have had similar results regarding the effectiveness of Covid vaccines in preventing infection and hospitalization.
The effectiveness of the Pfizer vaccine in preventing hospitalizations remained stable at around 90% in all age groups for six months after injections
The vaccine’s effectiveness in preventing infection declined over time, falling below 50%, although there was no difference between age cohorts
Study results show that a recent increase in breakthrough cases may have less to do with factors specific to the Delta variant, but rather with declining vaccine effectiveness over time.
These revolutionary cases are less serious, however, with the vaccine still showing the ability to prevent hospitalizations and deaths.
“Our variant-specific analysis clearly shows that the [Pfizer] The vaccine is effective against all current variants of concern, including Delta, ”said Dr. Luis Jodar, senior vice president of Pfizer Vaccines, in a statement.
“COVID-19 infections in people who have received two doses of the vaccine are most likely due to decline and not caused by Delta or other variants beyond vaccine protection. ”
For the study, published in The Lancet, the team collected data from 3.4 million members of the KPSC health network.
They analyzed health records to determine how often people tested positive or required medical treatment due to the virus.
People whose data were included in the study were separated by age to find potential differences in vaccine effectiveness within six months of the second jab.
Researchers found little difference between age cohorts in the ability to prevent hospitalizations or infections.
Among all age groups, the vaccine’s effectiveness slowly declined over the months, eventually dropping to around 50 percent.
Overall, the vaccine was shown to be 73 percent effective in preventing infection during the first six months after vaccination.
Efficacy against hospitalization remained stable for all ages, showing little change in the first six months.
Other studies have found similar results, including an August Mayo Clinic study which found that Pfizer vaccine was only 42% effective in preventing infection in July, although it remains 75% effective in preventing hospitalization.
At the time, the Delta variant was believed to be the cause of the drop in efficiency, although the KPSC findings indicate otherwise.
Another study from the Centers for Disease Control and Prevention also found that the effectiveness of the Pfizer vaccine declined to around 50 percent over time.
The results match what many health officials have said in recent weeks in conversations about Covid booster shots.
The White House wanted to roll out boosters for all Americans from September 20, citing the decline in vaccine effectiveness as the reason for the third injections.
Some officials and experts disagreed, including 18 senior officials from the Food and Drug Administration (FDA) who released a report opposing the recalls last month, citing instead the vaccine’s effectiveness in preventing the recalls. hospitalizations as a reason why reminders are not needed.
The FDA has refused to allow boosters for all Americans over 18, instead allowing Pfizer boosters to be used for Americans aged 65 or older or with a co-morbid condition that makes them vulnerable to the virus.
Eligible Americans quickly took advantage of the availability of boosters, with nearly two million shots administered last week, the White House reported.