According to a study that analyzed Omicron waves in Qatar, two doses of the COVID-19 vaccine are associated with negative protection against the disease, scientists say.
Research published in New England Journal of Medicine On June 15, we investigated the Omicron waves in Qatar from around December 2021 to February 2022 and compared the immunization rates and immunity of more than 100,000 Omicron-infected and non-infected individuals.
The authors of the study found that previously infected but unvaccinated individuals were 46.1% and 50% immunized against the two subvariants of the Omicron variant, even at intervals of 300 days or more from the previous infection. I found that I have it.
However, those who have been vaccinated twice with Pfizer and Moderna but have never been infected before show negative immunity to both BA.1 and BA.2 ocmicron subvariants, averaging. It shows that the risk of getting COVID-19 is higher than that of humans.
More than 6 months after receiving the Pfizer vaccine twice, the immunity to Omicron infection decreased to -3.4%.
However, with two doses of the Moderna vaccine, immunity to Omicron infection dropped to -10.3% more than 6 months after the last injection.
The authors report that three doses of Pfizer vaccine increased immunity by more than 50%, measured over 40 days after the third dose, at very short intervals. .. By comparison, innate immunity persisted at about 50% when measured more than 300 days after the previous infection, but immune levels dropped to negative levels 270 days after the second dose of the vaccine.
These numbers indicate the risk of weakened immunity to the third dose of vaccine over time.
The findings are supported by another recent study from Israel that found that innate immunity declines significantly more slowly compared to artificial or vaccinated immunity.
The study found that both innate and artificial immunity declined over time.
Individuals who were previously infected but not vaccinated had half the risk of reinfection compared to individuals who had been vaccinated twice but were not infected.
Dr. Martin Adel McCulley, a public policy researcher at Johns Hopkins University, wrote on Twitter that “innate immunity wins again,” referring to Israeli research.
“Among those who have previously been infected with SARS-CoV-2, protection against reinfection has diminished over time,” the authors conclude. vaccination.
Enrico Trigoso contributed to this report.