In a new study using the Gamma variant of coronavirus recovered from patients, researchers in the US and Japan have found that vaccination with an mRNA vaccine induces antibody responses that would protect humans from infection with the gamma or P.1 variant.
This variant, known as gamma, or P.1, led to a deadly surge in COVID-19 cases in Brazil this spring and has now spread across the world. Research is underway to determine whether current vaccines are as effective against the gamma variant. The Centers for Disease Control and Prevention recently had designated the delta version as a variant of concern due to evidence that it transmits more readily.
Researchers said that hamsters used in the study, who were previously infected with the initial virus strains, were protected from infection with the gamma variant nine months later. The findings, the researchers say, suggest that previous SARS-CoV-2 infection and vaccines that are based on earlier strains of the virus still protect against infection with gamma.
Yoshihiro Kawaoka, a professor of virology at the University of Wisconsin and study lead, said that the animals were quite protected, “There may be people who get infected with this variant even though they are vaccinated or were previously infected, but they shouldn’t get the severe disease. However, that is not consistent with what has been happening in Brazil.”
There have been reports of people reinfected with the gamma variant after recovering from infection with an earlier strain in Brazil. Kawaoka explained that COVID-19 immunity may last longer in hamsters than in humans, or that cases documented as reinfections are first infections.
The researchers say these findings suggest there are some important differences in the spike protein of gamma that might influence immunity, warranting further monitoring. They also added that the Delta variant may become prevalent in the absence of large-scale vaccination.
The study was published in the Proceedings of the National Academy of Sciences on June 17, 2021, under the title “Characterization of a new SARS-CoV-2 variant that emerged in Brazil”.