The challenge of finding new ways around the immunity humans have built up through vaccines is daunting. It is up to the challenge. Several new and highly immune-evasive strains of the virus have caught the attention of scientists, and one or more may cause big waves this fall and winter.
It is certain that something is coming. A researcher at the University of Basel says that there are probably more than one thing to come. The big question is whether they will cause a lot of hospitalizations and deaths.
"It's not surprising that we're seeing changes that help the virus to evade immune responses, it's the same challenge that things like the common cold and flu face every year."
Omicron, which swept the globe over the past year, is one strain that looks poised to drive the latest comeback. The initial strain of Omicron, which was derived from BA.2, was outcompeted by the newer strain of Omicron, which was derived from BA.5. In India, Singapore, and parts of Europe, one of these is spreading quickly. BQ. 1.1 is one of the newer immune-evading strains and has been seen in many countries around the world.
A striking example of convergent evolution is the fact that several of the new strains have a similar combination of genes. According to evolutionary biologist Jesse Bloom of the Fred Hutchinson Cancer Center, all of them have changes in the viral genome that affect how well the immune system works.
To measure how well the immune system can protect against new subvariants, researchers make copies of the viruses and expose them to people who have the same immune system. Researchers in China and Sweden have found that spikeprotein from BA.2.75.2 can effectively evade nearly all the monoclonal antibodies used for treating COVID-19, suggesting that these treatments may become useless.
The groups found that BA.2.75.2 was very good at evading immunity. According to a preprint posted on 19 September, the effectiveness of blood samples from 18 donors in Stockholm was less than the effectiveness of samples from other donors. Daniel Sheward says this is the most resistant variant they have evaluated.
After testing blood samples from 40 people who had beenvaccinated with three doses of CoronaVac, a vaccine made from inactivated virus, and 100 more who had beenvaccinated and had breakthrough infections, the same results were found for BA. 2.5.2. BQ. 1.1 had a similar ability to evade the immune system.
The new variant of the virus does not seem to have lost its ability to bind to the receptor on human cells, which means the variant's infectiousness hasn't decreased. A huge new wave could be portending all of that. He says that the immune evasion has never been seen before. I think it is very bad.
They agree that we should expect a lot of infections in the next few months. Many more people have recovered from infections now or have received additional vaccine doses, which is why they are less pessimistic. Sheward says: "I don't believe we're back to square one."
The choice of putting BA.5 in the vaccine booster is still looking good. The good news is that the BA.5 booster will be one or two steps behind the evolution of the virus.
Once more people are exposed to the new strains of coronaviruses, it will be clear how brutal a comeback it has been. It is possible that the next wave will provide better clues about what causes disease.
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