Variant in SA may lead to better vaccines
Antibodies generated in response to the new coronavirus variant dominating transmission in SA appear to provide protection against infection with several other strains, a discovery that could pave the way for better vaccines, SA scientists announced on Wednesday.
The 501Y.V2 variant was detected by scientists from the KwaZulu-Natal Research Innovation and Sequencing Platform (Krisp) late last year, and now accounts for virtually all infections in SA. It was classed as a “variant of concern” by the World Health Organization, because it spreads more easily and can infect more people than the original Sars-Cov-2 virus. It has now been detected in 48 countries.
The 501Y.V2 variant has also thrown up a major challenge for vaccine developers, as they crafted their shots to confer protection against the wildtype virus first detected in Wuhan, China. It has quickly become apparent that their products are less effective against 501Y.V2, to the extent that SA halted its planned rollout of AstraZeneca’s shot after a small trial found it offered minimal protection against mild to moderate illness.
Laboratory tests have shown 501Y.V2 reduced the neutralising effect of antibodies produced in response to the vaccines made by Pfizer, Moderna, and Sinopharm, while clinical studies have shown a reduced effect for shots developed by Johnson & Johnson, Novavax and AstraZeneca.
Local scientists have discovered that plasma collected from people infected with 501Y.V2 in SA’s second wave of infections contains antibodies that not only knock out 501Y.V2, but also provide some protection against the older lineage circulating in the first wave. By contrast, people infected with the original variant generate antibodies that have limited capacity to neutralise 501Y.V2.
“We were literally floored by this result,” said the Africa Health Research Institute’s Alex Sigal. “It seems if you are infected with this variant, or you can design a vaccine with this variant, it might be cross-protective, and might leave the virus with not much room to go. This of course to us was incredible,” he said.
Previous work by a team at the National Institute for Communicable Diseases led by Penny Moore found 501Y.V2 could completely evade the antibodies generated in response to infection in SA’s first coronavirus wave in almost half the samples they studied. They also found 90% of these samples contained antibodies that were less effective at neutralising 501Y.V2.
Her team has also investigated how antibodies generated in response to 501Y.V2 shape up against P1, the variant first detected in Brazil, and found they had some neutralising effect against this strain.
More work was now needed to determine why 501Y.V2 generated antibodies that offered a greater breadth of protection than other variants, said Moore. “That will be crucial to understanding the risk of reinfection and vaccine design,” she said.
Moore cautioned that scientists still did not know how long antibody protection lasted. “We strongly encourage people who have been infected to still pursue the same non-pharmaceutical interventions,” she said.
Analysis by the Network for Genomic Surveillance in SA, which regularly sequences coronavirus samples collected in Gauteng, KwaZulu-Natal, Western Cape and Free State, shows the 501Y.V2 variant accounted for just 11% of infections in October. By December, it was identified in 87% of the samples collected. And by February it accounted for 99% of the analysed samples.
Coronavirus mutations are common and generally do not make news headlines. But the 501Y.V2 variant has scientists worried because it has several mutations in its spike protein, which the virus uses to infect human cells. Scientists speculate that these mutations might make it easier for the virus to enter human cells, and may explain its increased transmissibility.