Pfizer: COVID-19 vaccine still effective six months after shots

Chris Davies - Apr 1, 2021, 11:27am CDT
Pfizer: COVID-19 vaccine still effective six months after shots

Months into the COVID-19 immunization rollout, new data from Pfizer suggests its vaccine has been 100-percent effective in preventing severe cases of coronavirus, with the effects of the drug lasting for more than six months. The new study built on Pfizer-BioNTech’s original immunization research, following participants who had been injected with BNT162b2 to see who had gone on to catch COVID-19.

As the initial results – which helped BNT162b2 secure an emergency use authorization (EUA) from the US Food and Drug Administration (FDA) – indicated, the vaccine candidate is 100-percent effective at preventing what the US Centers for Disease Control and Prevention (CDC) defines as “severe disease.” That’s cases of coronavirus which lead to hospitalization or even death.

As for general cases of COVID-19, BNT162b2 now showed 95.3-percent efficacy. That’s as measured from seven days through to up to six months after the second dose. Like Moderna’s vaccine, Pfizer-BioNTech’s requires two doses – separated by roughly 3-4 weeks – in order to be most effective.

In total, the pharma companies said today, BNT162b2 is 91.3-percent effective against COVID-19. That’s based on 927 confirmed cases of coronavirus through March 13, 2021. 46,307 participants were involved in the trial; of the confirmed cases, 850 were in the placebo group that did not receive the vaccine.

77 cases were of individuals who had received the vaccine, but still went on to get COVID-19. However, none were classed as severe cases according to the CDC definition, though one was according to the FDA definition.

As for the six month result, that appears to be more about the length of time the study has been operating than a final figure for how long immunity actually lasts. Of the participants in the trial, over 12,000 who were vaccinated received the shots six months ago or more.

The data also indicates Pfizer-BioNTech’s vaccine is effective agains the South Africa COVID-19 variant, the pharmaceutical companies confirmed. In addition, there’s also good news for concerns around side-effects.

“No serious safety concerns were observed in trial participants up to six months after the second dose,” Pfizer-BioNTech said today. It plans to submit its data for peer review and potential publication, as well as part of an eventual Biologics License Application for BNT162b2. That will begin the process of the drug gaining full approval by the FDA, rather than being permitted for use during the pandemic under the emergency rules

Earlier this week, Pfizer-BioNTech confirmed it was undertaking trials of the vaccine with children and adolescents. One study, which looked at participants aged 12-15, found 100-percent efficacy and “robust antibody response” among the immunized cohort. Similar studies are underway with younger age groups.


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