CoronaVac less effective against Gamma variant

The Chinese CoronaVac jab, a key tool in Brazil’s fight against Covid-19, is less effective against the Gamma variant first detected in the virus-ravaged South American country, a study said Friday.

Researchers found that antibodies generated by the vaccine work less well against the variant than a previous coronavirus strain, while Gamma may also be able to reinfect people who had previously had the virus. 

Gamma’s capacity to evade these immune system responses even in immunized people suggests “the virus can potentially circulate in vaccinated individuals – even in areas with high vaccination rates,” the study authors said in a press release. 

In the small study, researchers at the University of Campinas in Brazil exposed both Gamma and a previous strain of the virus to antibodies in blood plasma from 53 vaccinated people and 21 people who had been previously infected with the virus.

In the vaccinated group, 18 people had received only one dose of CoronaVac – one of the main vaccines in Brazil’s coronavirus response – while 20 had recently received a second jab and a further 15 had been vaccinated as part of the Sinovac clinical trial in August 2020.