Pfizer jab highly effective against severe COVID for at least six months, suggests study
Pfizer and healthcare provider Kaiser Permanente examined information from 3.4 million southern California individuals, almost one-third of whom were vaccinated entirely between December 2020 and August 2021.
FollowVaccination with two doses of the Pfizer jab remained highly effective against severe Covid — including the Delta form — for at least six months, a review of US patients revealed Monday.
While earlier evidence from clinical trials has indicated jabs protect against hospitalisation, the study published in the Lancet examines one vaccine's effectiveness over time in a real-world environment. Pfizer and healthcare provider Kaiser Permanente examined information from 3.4 million southern California individuals, almost one-third of whom were vaccinated entirely between December 2020 and August 2021.
After three to four months, fully vaccinated people were found to be 73% protected against sickness and 90% protected against hospitalisation. But while protection against infection from Delta dropped by 40 per cent after five months, protection against hospitalisation, including cases from all variations, remained relatively high for the length of the research. The results, the research says, are comparable with early data from US and Israeli health authorities.
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The authors believe that decreasing infection defence is "likely to be largely attributable to diminishing vaccination efficacy rather than the delta variant evading vaccine protection", the scientists write. "Our findings emphasise the significance of monitoring vaccine efficacy over time and imply that booster doses are likely to be needed to restore the initial high rates of protection observed early in the immunisation campaign," it adds.
In August, the US allowed an additional dosage of Covid-19 vaccination for those with weaker immune systems, while in France, an extra injection has been provided to the elderly. Israel has gone a step further, providing youngsters aged 12 and above a third dosage five months after getting the first. However, a September assessment from the World Health Organization (WHO) concluded existing vaccinations are efficacious enough against severe Covid to make a third jab unnecessary for the general population. Last month, the WHO asked for a halt on booster shots until the end of the year to address the severe imbalance in dosage distribution between affluent and developing nations.
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