 "Pfizer Vaccine, Coronavirus vaccine")
Pfizer Inc and BioNTech SE said on Thursday they are testing a third dose of their Covid-19 vaccine to better understand the immune response against new variants of the virus.
They are also in talks with regulatory authorities about testing a vaccine modified to protect specifically against the highly transmissible new variant found in South Africa and elsewhere, known as B.1.351, as a second arm of the same study.
The companies believe their current two-dose vaccine will work against the South African variant as well as one found in the United Kingdom and elsewhere. But the studies will allow the
