COVID-19 vaccination effective against delta variant, researchers say
Researchers at Washington University School of Medicine in St. Louis (WUSTL) have found that the delta variant of the virus causing COVID-19 is not more resistant to antibodies elicited by vaccination. According to WUSTL associate professor of medicine Dr. Jacco Boon, the delta variant is “[not evidently] better at overcoming vaccine-induced immunity compared to other variants.”
Dr. Boon goes on to explain the ability of a virus variant to spread is dependent on many factors, including resistance to antibodies and the rate of replication.
Read also: Antibodies against COVID-19 vary with vaccination vs natural infection
It follows then, that an ideal antibody response will include a diverse set of antibodies with the flexibility to recognise even slightly different variants of the virus: while the length of the antibody response is only one aspect of protection; breadth confers resilience – even if a few antibodies lose the ability to recognise a new variant, other antibodies in the arsenal should remain capable of neutralising it.
In an analysis of the antibody response to SARS-CoV-2, the virus that causes COVID-19, by WUSTL professor Dr. Ali Ellebedy and colleagues, antibody-producing cells were extracted from three people who had received the Pfizer vaccine. A set of 13 antibodies was finally obtained from the cells after culture in a lab; the antibodies would target the original coronavirus strain that began circulating last year.
When these 13 antibodies were tested against four variants of concern: alpha, beta, gamma, and delta, twelve of the 13 were shown to recognise alpha and delta, eight recognised all four variants, and one failed to recognise any of the four variants. More specifically, five of the 13 antibodies could neutralise the original strain and the delta variant; three neutralised alpha and delta, and only one neutralised all four variants.
[An antibody is said to be effective based on its ability to block a virus from infecting and killing cells in a dish. So-called neutralising antibodies that prevent infection are thought to be more powerful than antibodies that recognise the virus but can’t block infection, although both neutralising and non-neutralising antibodies contribute to defending the body.]
The antibody that neutralised all four variants of concern—as well as three additional variants tested separately—was called 2C08.
Some people may have antibodies just as powerful as 2C08 protecting them against SARS-CoV-2 and its many variants. The researchers discovered that about 20% of people infected or vaccinated against SARS-CoV-2 create antibodies that recognise the same spot on the virus that is targeted by 2C08. Moreover, very few virus variants (.008%) carry mutations that allow them to escape antibodies targeting that spot.
“Similar antibodies have been generated by people infected in Italy and China and people vaccinated in New York. So, it’s not limited to people of certain backgrounds or ethnicities; it’s not generated only by vaccination or by infection. A lot of people make this antibody, which is great because it is very potent and neutralises every variant we tested, “Dr. Ellebedy said.
The presence of 2C08 helps explain why vaccinated people have largely escaped the worst of the delta surge.
“In face of vaccination, delta is relatively a wimpy virus. If we had a variant that was more resistant like beta but spread as easily as delta, we’d be in more trouble.”
