As time goes by, the immunity generated by COVID-19 vaccines decreases, this has led to the promotion of booster doses in the population. A study, conducted by members of the nonprofit organization Kaiser Permanente, has found that the protection of the booster dose of Pfizer-BioNTech against the omicron variant in terms of hospitalizations is reduced from the third month after its injection .
The research, which has been published in the journal The Lancet Respiratory Medicine, has indicated that Pfizer’s COVID-19 vaccine offers protection of between 80% and 90% in the first months against hospitalizations and in the risk of having to go to the Emergency Room for problems caused by the delta and omicron variants.
However, the researchers found that this protection against omicron could decrease over time, even when it is a booster dose. The tests were conducted on a group of 11,123 patients who attended emergencies or were admitted to hospitals in Southern California between December 1, 2021 and February 6, 2022, at which time delta and omicron were in circulation.
The effectiveness is reduced after three months
The results showed that after the complete schedule of two doses of vaccination with the Pfizer drug, the effectiveness against the omicron variant was 41% against hospitalization and 31% in emergency visits at nine months. In addition, with three doses the efficacy in preventing hospitalization for omicron was 85% at less than three months, but this figure fell to 55% at three months or more.
“Additional doses of current, adapted or novel COVID-19 vaccines may be needed to maintain high levels of protection”
Regarding the need to visit the ER with problems derived from the omicron variant having three doses of Pfizer’s COVID-19 vaccine, the researchers found that there was 77% effective protection at less than three months, but that dropped to 53% from that time.
“Although Pfizer COVID-19 protection levels against omicron after three doses are substantially higher than those observed after two doses, they are lower than those observed for delta or other strains of COVID-19. Additional doses of current, adapted, or novel COVID-19 vaccines may be needed to maintain high levels of protection against subsequent waves of COVID-19 caused by omicron or future variants with similar potential to escape protection.” Y. Tartof, one of the authors of the study.
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