New Jersey: Pfizer Inc and BioNTech SE said Thursday that 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 specifically testing a modified vaccine to protect against the new transmissible 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 in addition to the one found in the UK and elsewhere.
But they said the studies would allow vaccine makers to prepare if and when more protection is needed.
“The rate of mutation in the current virus is higher than expected,” said Michael Dolston, chief scientific officer of Pfizer, in an interview.
“It is a reasonable possibility that we will end up with the regular boosters. For strong vaccines, you may need to change the strain every few years, but not necessarily every year.”
In the Phase 1 study arm, a third dose of 30 mcg will be given to up to 144 people who received the vaccine 6 to 12 months ago in the original Phase 1 safety trial.
Assuming regulatory approval, Dolston said, a redesigned vaccine will also be tested, as a booster dose, in people who have been vaccinated and in people who have not yet received the vaccine.
The trial will not seek to measure the effectiveness of the vaccine like the large phase 3 trial last year.
Instead, it will measure the antibody’s response and study whether blood from recipients can neutralize new variants of the Coronavirus, as well as the safety of a third dose.
The United States discovered its first case of the South African type in January, and it has since appeared in 14 states, according to US government data.
Several studies indicate that it is more resistant to existing vaccines than other variants of the Corona virus.
Pfizer’s Dolsten said mRNA vaccines like Pfizer and BioNTech create a robust response.
But the immune response may diminish over time.
He believes that a third dose of their vaccine will create a similar or better response than the second dose, and it could be the next logical step to stay ahead of the current variables.
“We believe our vaccine is strongly effective against all strains,” Dolston said, noting that companies “want to be prepared for all options and for the data to be science-driven.”
Dolsten said the new trial is likely to take place mostly in the United States.
Moderna Inc said on Wednesday that it is also working with US government scientists to study an experimental booster dose that targets the type that was first discovered in South Africa.