A group of independent researches published findings last week, showing that neutralizing antibodies critical in fighting against COVID-19 infection diminish considerably within six months of receiving the Pfizer vaccine.
The story: The research indicates that the levels of neutralizing antibodies drop by nearly a factor of 10 within seven months of receiving the second dose of the Pfizer vaccine, with neutralizing antibodies not detectable at all after six months in nearly half of the subjects studied.
The researchers studied the immune responses of 56 healthy volunteers who received two doses of the Pfizer vaccine. In addition to the original strain of COVID-19, the researchers also studied the antibody responses to other emerging variants, including the Mu variant.
“Our data demonstrate a substantial waning of antibody responses and T cell immunity to SARS-CoV-2 and its variants, at 6 months following the second immunization with the [Pfizer] vaccine,” the team wrote in their report.
The researchers’ comments: Stanford researcher Bali Pulendran and Emory researcher Mehul Suthar also told Reuters by email: “Our study shows vaccination with the Pfizer-BioNtech vaccine induces high levels of neutralizing antibodies against the original vaccine strain, but these levels drop by nearly 10-fold by seven months.”
The researchers noted that the body has a host of immune responses that help combat infection, but neutralizing antibodies “are critically important in protecting against SARS-CoV-2 infection.”
Thus, the researchers conclude, it would be necessary to administer a booster shot after about six months in order to keep neutralizing antibody levels high enough to battle infection.
“These findings suggest that administering a booster dose at around 6 to 7 months following the initial immunization will likely enhance protection against SARS-CoV-2 and its variants,” they wrote.
Worth noting: A study published in July indicates that after being 96% effective for the first two months following the second shot, the efficacy of the Pfizer vaccine falls to about 83.7% at six months.
“The third dose elevates the neutralizing antibodies in our laboratory studies to up to 100-times higher levels post-dose three compared to pre-dose three,” Pfizer’s chief scientific officer Mikael Dolsten said on a recent call with investors.
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