Pfizer Boosters Could Protect You for This Long, Leaked Research Shows
Preliminary data also shows that the third shot yields more antibodies.
While many young people across the U.S. who recently became eligible are getting their first doses of vaccine, many in the older and higher-risk population are getting their booster shots to shore up their immunity against COVID-19. According to the Centers for Disease Control and Prevention (CDC), 31,464,669 people have received the supplemental shot so far, as of Nov. 17. Health officials have pointed to the effectiveness of the extra dose as a reason for those who are eligible to get one. Now, leaked research is giving the first insights into how long a Pfizer booster might be able to protect you from the virus.
The latest information comes from a study conducted by the Tel Hashomer Hospital in Israel and sent to Channel 12 news on Nov. 7, The Times of Israel reports. The data, which is set to be made public in one to three weeks, shows that Pfizer boosters appear to be effective for at least nine to 10 months after receiving them.
While no information on the research methodology was revealed, people involved with the study told Channel 12 that the third dose yielded more antibodies than previous shots. They also said the antibodies generated were better at warding off the virus and offered a different kind of protection than the initial two doses.
To date, Israel has provided much of the available data on boosters due to its early adoption of Pfizer boosters shots on a large scale. One study, conducted by the Clalit Research Institute and published in the journal The Lancet on Oct. 29, analyzed health record data from July 30, 2021, through Sept. 23, 2021. Researchers then carefully matched 728,321 patients who had received the initial two doses of the Pfizer COVID-19 vaccine at least five months earlier with 728,321 patients who had received a third shot.
Results found that patients who received Pfizer booster shots were at a 93 percent lower risk of being hospitalized, a 92 percent lower risk of severe disease, and an 81 percent lower risk of death from COVID-19 compared to those who had only received their initial two shots. The researchers also noted that the booster's effectiveness was similar for sexes, age groups, and the number of comorbidities that increased health risk.
"To date, one of the main drivers of vaccine hesitancy has been a lack of information regarding the effectiveness of the vaccine," Ben Reis, PhD, director of the Predictive Medicine Group at Harvard Medical School and the Boston Children's Hospital Computational Health Informatics Program, said in the press release. "This careful epidemiological study provides reliable information on third-dose vaccine effectiveness, which we hope will be helpful to those who have not yet decided about vaccination with a third dose."
While the leaked Tel Hashomer Hospital study represents some of the earliest insights into how long a Pfizer booster may be effective, other existing vaccines could also help suggest just how long an extra dose can protect you. According to John Wherry, PhD, director of the institute for immunology at the University of Pennsylvania, both vaccines and boosters create an initial burst of antibodies that peak one to two weeks after the shot has been administered before declining and stabilizing over time. However, booster antibodies tend to stabilize in the body better than those created after initial doses.
"The slope of decay is shallower," he told The Wall Street Journal. "The question is: Does [the level of antibodies] settle at a higher level and at a more steady level than it did with the primary vaccination?" he added. "That's the hope."
Many have also credited the use of booster shots in Israel with helping the country stave off rising infection counts, The Times of Israel reports. After surging to more than 90,000 active COVID cases in September, numbers had dropped to just under 6,000, according to data released by the Israeli Health Ministry on Nov. 8.