Results from a National Institute of Communicable Diseases (NICD) study shows that immunity gained against the initial strains of SARS-CoV-2 is blunted against the new 501Y.V2 strain that originated in South Africa.
The new variants which are more transmissible have mutations to their spike proteins that give the coronavirus its distinctive shape—and to which immune antibodies bind. Scientists have been concerned that the new strains may also escape vaccine containment, especially the E484K mutation, which has been observed in new strains found in Brazil and South Africa.
In the study, which is awaiting peer review, researchers took plasma from patients who had recovered from the original COVIDs, and tested those samples against the 501Y.V2 virus variant to measure antibody reaction. The virus was more resistant to these antibodies, which had been built up from previous infections. “Here we show that the 501Y.V2 lineage, which contains nine spike mutations and rapidly emerged in South Africa during the second half of 2020, is largely resistant to neutralising antibodies elicited by infection with previously circulating lineages,” said the researchers.
“This suggests that, despite the many people who have already been infected with SARS-CoV-2 globally and are presumed to have accumulated some level of immunity, new variants such as 501Y.V2 pose a significant re-infection risk.”
The researchers noted that these findings may have implications for those treated with convalescent plasma (a donor programme for which is run by the South African National Blood Service). Additionally, there were “implications” for those vaccines that were developed based around an immune response to the virus’ spike proteins.
Vaccines may therefore have to be adjusted to account for the new spike mutation in order to retain effectiveness against variants possessing that mutation. The developers of the Oxford/AstraZeneca vaccine are already preparing to proactively adjust their vaccines to account for the new strains emerging around the world.
Commenting to the Science Media Centre, Lames Naismith, Director of the Rosalind Franklin Institute said that it was “not good news but it’s not unexpected.
“He said that real-world immune responses are more complicated than those of the blood plasma neutralising antibodies. “The vaccines do stimulate very strong responses, immunity is a sliding scale, it’s not an on/off switch,” he explained.
In another study posted online, it was reported that antibodies from recovered patients did mostly protect against B.1.1.7, the variant that originated in the UK.
“Our results suggest that the majority of vaccine responses should be effective against the B.1.1.7 variant,” concluded researchers from one the UK/Netherlands studies.
A separate study showed that the Pfizer/BioNTech vaccine also appeared to confer protection against that variant as well, with the authors concluding that it was “unlikely” that the B.1.1.7 variant could escape vaccine protection.
Source: Medical Xpress
