Pfizer-BioNTech vaccine decreases chances of hospitalisation from Covid-19 across all variants; finds study

The study published in The Lancet has found that the vaccine is effective up to 90 per cent across all variants for six months for beneficiaries who have received both doses.

October 5, 2021 15:42 IST

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New Covid study to establish effectiveness of vaccine

Pfizer-BioNTech vaccine is effective in reducing hospitalisation for Covid-19 cases across all variants, says a new study by Kaiser Permanente and Pfizer. The study published in The Lancet has found that the vaccine is effective up to 90 per cent across all variants for six months for beneficiaries who have received both doses. The study was conducted on subjects in the United States.

Findings of the study

Although the vaccine proved effective against hospitalisation, the efficacy declines against all SARS-CoV-2 variants from 88 per cent within one month to 47 per cent in six months after receiving two vaccine doses. Effectiveness against hospitalisation remained at 90 per cent all through for all variants.

The findings look close to what the US Centers for Disease Control and Prevention (CDC) and those of the Israel Ministry of Health concluded about reductions of BNT162b2 against infection after approximately six months, the study authors noted.

Analysis of the study

A total of 3,436,957 electronic health records from the Kaiser Permanente Southern California (KPSC) health system were analysed between December 4, 2020 and August 8, 2021. Among those infected, 6.6% (12,130) were hospitalised and 5.4% (184,041 people) were infected with SARS-CoV-2 in an average four months period.

Genome sequencing of the samples further determined that 28 per cent of the positive cases were caused by the delta variant. Moreover, the proportion of positive cases from the Delta variant increased nearly from 0.6 per cent to 87 per cent in four months, making research come to consensus that the Delta variant was the dominant strain in the study.

While vaccine effectiveness against delta variants fell from 93 per cent to 53 per cent in four months, for other variants on receiving both doses it declined from 97 per cent in the first month to 67 per cent in four months. Vaccines protected Delta variant positive cases from hospitalisation 93 per cent of the times.

However, the rate of waning for Delta compared to other variants is warranted with longer follow-up.

Takeaways

The study establishes the importance of vaccination and the importance of monitoring vaccine effectiveness to understand the most vulnerable section of the population who should be prioritised for booster doses.

As CDC Advisory Committee on Immunization Practices asked for additional research to find out if booster shots should be made available to all age groups eligible for this vaccine, especially when many country around the world is yet to start first phase of vaccination, the study proved that immunity wanes ebbs for all irrespective of any age group they belong to, the study’s lead author Dr Sara Tartof, from Kaiser Permanente, said in a statement affirmed