In a glimmer of hope in the race to outsmart the Covid-19 501Y.V2 variant, scientists in South Africa have shown that antibodies produced from infection with 501Y.V2 can protect against other circulating variants.
The findings have important implications for future vaccine design.
The research team was the first to isolate the 501.YV2 variant as a live virus, and in early 2021 they demonstrated, in a laboratory setting, that 501Y.V2 can escape antibodies generated from infection with previous variants. These results were later backed by vaccine trials as well as work on vaccine elicited antibodies by the Sigal group, which showed that some vaccines have reduced efficacy against 501Y.V2. This ultimately led to the South African government putting the roll-out of the AstraZeneca vaccine on hold in the country.
Sigal and his group then went on to test blood plasma samples from people infected with the 501Y.V2 variant against earlier variants of the virus. Unlike the weak cross-protection by plasma of people infected by earlier variants against 501Y.V2, which was 15-fold lower than the protection of plasma of 501Y.V2 infected people, the cross-protection of plasma antibodies made to fight 501Y.V2 also worked well against earlier variants of the virus, with a decrease of only 2-fold relative to plasma antibodies made to fight those earlier variants.
This means that the immunity that the variant produces is back-compatible, or effectively neutralises, older circulating variants of Covid-19, and is the first evidence that a vaccine designed specifically for 501Y.V2 could protect against other circulating Covid-19 variants. This research shows similar trends to recent work done by the National Institute of Communicable Diseases’ Penny Moore.
“This collectively suggests that there is a possibility we could get a vaccine which is broadly effective against all circulating variants. It would just need to be designed for current variants; perhaps 501Y.V2,” said Sigal.
His group’s next steps include understanding vaccine efficacy among healthcare workers enrolled in the current Johnson & Johnson vaccine trial in KwaZulu-Natal.
Top image: Neutralization of first infection wave and 501Y.V2 variants by convalescent plasma from South African first and second wave infections, from Cele et al.