Pfizer Vaccine Effective Against COVID-19 Hospitalizations for All Variants 

Two jabs of the Pfizer-BioNTech vaccine are 90% effective against COVID-19 hospitalizations for all variants including Delta, for at least 6 months, confirmed a new study published by The Lancet.

The study, conducted by Kaiser Permanete and Pfizer, found that while effectiveness against all SARS-CoV-2 infections declined over the study period, effectiveness against hospitalizations remains at 90% overall for all variants. 

“Our study confirms that vaccines are a critical tool for controlling the pandemic and remain highly effective in preventing severe disease and hospitalization, including from the delta and other variants of concern. Protection against infection does decline in the months following a second dose,” said lead author of the study Dr Sara Tartof, of Kaiser Permanente. 

The study analyzed 3,436,957 electronic health records from the Kaiser Permanente Southern California (KPSC) health system between 4 December 2020 and 8 August 2021 to assess the effectiveness of the Pfizer vaccine against COVID-19 infections and related hospitalizations. 

Immunity declines after six months

In addition, the study also found that effectiveness against all SARS-CoV-2 infections declined over the study period, falling from 88% within one month after receiving two doses to 47% after six months, underscoring the importance of improving vaccination rates worldwide. Researchers did not observe a difference in waning between variants.

While this does provide evidence towards waning immunity against COVID-19, the CDC has called for additional research to determine which groups should be prioritized to receive booster shots. 

“In line with the recent FDA [3] and CDC recommendations [4], considerations for booster shots should take global COVID-19 vaccine supply into account as people in many countries around the world have not yet received a primary vaccination series,” said Tartof. 

Vaccine equity and booster shots have prompted increasing debate in recent weeks, with WHO calling for a global moratorium on COVID-19 boosters to be extended until the end of the year, and global health advocates protesting “vaccine apartheid” outside the UN during the General Assembly last month. 

US and Israeli studies find similar reductions in immunity 

Other findings from the US Centers for Disease Control (CDC) and the Israeli Ministry of Health had also found reductions of immunity from the Pfizer vaccine after six months. 

The Israeli findings reported that people over age 60 who received a third dose of the Pfizer vaccine were five times less likely to become severely ill if they had their first shot at least five months earlier. 

These results in particular were regarded as a critical factor in the recommendation from the US Food and Drug Administration (FDA) to amend its emergency use authorization (EUA) last month for the Pfizer vaccine.

The FDA now recommends a single booster dose to be administered at least six months after completion for: individuals 65 and older; individuals 18 through 64 at high risk of severe COVID-19; and individuals 18 through 64 with increased exposure of SARS-CoV-2 that puts them at high risk of health complications relating to COVID-19. 


Image Credits: International Monetary Fund/Ernesto Benavides.

Combat the infodemic in health information and support health policy reporting from the global South. Our growing network of journalists in Africa, Asia, Geneva and New York connect the dots between regional realities and the big global debates, with evidence-based, open access news and analysis. To make a personal or organisational contribution click here on PayPal.