In the battle against COVID-19, the mRNA vaccines from Moderna and Pfizer-BioNTech have passed virtually every test for efficacy and safety. Now comes more positive news.
Researchers at the University of California and the Gladstone Institute of Virology in San Francisco have found that both vaccines induce strong T cell responses against two important coronavirus variants.
The T cell responses elicited by the two mRNA vaccines were identical against the B.1.1.7 (British) and B.1.351 (South African) variants and matched those against the original strain of the disease, the team found. In a pre-print version of the report, which has yet to undergo peer review, researchers said they'd found a "reassuringly unaltered T cell response against the variants."
A second dose of either vaccine affected the quantity but not the quality of T cells, the study found. This response, which was consistent against the original strain and the variants, shows the value of a second shot.
Another finding from the study: For those who had been infected with the virus, one mRNA vaccine dose is beneficial but a second shot isn’t necessary. Those recipients showed no increase in T cells after a second dose.
The study was conducted with eight individuals who received an mRNA vaccine. Four had been previously infected and were completely recovered from mild symptoms. The other four were infection free. Three specimens were obtained: Before vaccination, two weeks after the first dose and two weeks after the second dose.
For each of the 24 samples, the researchers measured the T cells’ response to the spike proteins of the original strain of COVID-19 and the British and U.K. variants.
The report backs up a study conducted by Pfizer, BioNTech and the University of Texas which showed that the vaccine produced by the two companies was effective against three variants, including the P.1 strain from Brazil.
Earlier this month, Moderna released results of a phase 2 study that showed its tweaked booster shot provided additional protection against the original strain of the virus as well as the variants from Brazil and South Africa.