Pfizer Details Plans for Studying Booster Shots Against Variants

Pfizer Inc. and partner BioNTech SE have begun a clinical study to see if a third shot of their existing Covid-19 vaccine can stimulate stronger immune responses against new variants.

The clinical trial will examine safety and immune responses of a third dose of the vaccine in as many as 144 people who participated in the companies’ Phase 1 study. The dose is being given six to 12 months after the initial two-dose regimen, and researchers will test blood from the participants to see if it enhances levels of antibodies produced against new strains from South Africa and elsewhere.

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