The third dose of the Pfizer vaccine may provide sufficient protection against omicron and other SARS-CoV-2 variants, but it is not for long term. Research has found that the booster dose is only highly effective for three months. 

A new study published in The Lancet Respiratory Medicine journal reported how the protection afforded by the third Pfizer vaccine dose deteriorates over time, sparking concerns on what should be the best long-term vaccination strategy amid the ongoing pandemic. 

Pfizer Vaccine Durability

In the study led by Sara Y. Tartof, PhD, the team examined the protection from current COVID-19 vaccines against the omicron variant since this area is still not well-characterized in the medical community. According to the researchers, they wanted to evaluate the “effectiveness and durability” of the two-dose and three-dose preparations of the Pfizer vaccine against hospitalizations and emergency department admissions due to the omicron and delta strains. 

The team analyzed 11,123 hospital admissions and emergency department visits at Kaiser Permanente in Southern California from Dec. 1, 2021, to Feb. 6, 2022 — covering the periods when the delta and omicron variants were widespread. They then reported their findings in their study published on April 22. 

For the two doses, Tartof and her colleagues found that the vaccine was 41% effective against hospital admission and 31% against emergency department visits at nine months or longer after the second dose. For the three-dose setup, the effectiveness and durability of the booster was notably high. However, the rate markedly dropped over time. 

“Pfizer BioNTech COVID-19 booster doses significantly improve protection against omicron, although that protection seems to wane after three months against emergency room visits, and even for hospitalization. Trends in waning against delta-related outcomes were generally similar to omicron, but with higher effectiveness at each time point than those seen for omicron,” Tartof was quoted by SciTechDaily, as saying. 

The researchers said the third Pfizer dose provided strong protection, roughly 85%, against hospitalization due to omicron and other strains. However, this dropped to 55% at three months or longer. Against emergency department admission, the initial figure was 77%. It fell to 53% after three months. Because of this, the team recommended getting additional doses of “current, adapted, or novel COVID-19 vaccines” to stay protected against the subsequent waves of SARS-CoV-2. 

“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,” Tartof explained. 

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