The BA.2.12.1 substrate of omicron is expected to become dominant in the United States, currently accounting for an estimated 36.5 percent of all cases of SARS-CoV-2 in the United States, according to the Latest Estimates Released Tuesday by the Centers for Disease Control and Prevention.
The rise of the variant is the latest in rapid succession of omicron subvariables, from the sky-scraping peak of cases from the first omicron subvariant BA.1 in January, to the current bump pushed by the BA.2 variant, which achieved dominance in March. As before, the reason for viral rape is that omicron sub-variables continue to develop advantages: BA.2.12.1 has a transport advantage over BA.2, which has a transport advantage over BA.1, which has a significant advantage over delta.
The imminent era of BA.2.12.1 raises concern about another wave of infection and raises questions about the efficacy of future Omicron-specific vaccines against occasional infections.
The good news, so far, is that current vaccines still strongly protect against severe COVID-19, and BA.2.12.1 does not appear to cause more serious disease than BA.1 or BA.2 — despite the CDC ) and other health experts are actively monitoring this. However, the subvariant appears to be able to evade immune protections, particularly those from previous BA.1 infection.
at Preliminary data was published online on Monday, researchers in Beijing found that BA.2.12.1 showed “strong neutralization evasion” against antibodies from vaccinated people who also had BA.1 infection. In the study, participants were vaccinated with Sinovac’s CoronaVac, an inactivated whole virus vaccine, which contained about 50% efficacy in early observational studies in Brazil. (MRNA-based vaccines have shown efficacy rates of about 95 percent in initial clinical trials.)
The researchers looked at neutralizing antibodies from 50 people who received three doses of CoronaVac and recovered from BA.1 infection. By comparing levels of neutralizing antibodies on a group of coronavirus variants, the researchers found that neutralizing antibody levels against BA.2 were about 1.86 times lower than they were for BA.1. But, things got worse as the researchers moved to newer subvariables: neutralizing antibody levels were 3.73 times lower for BA.2.12.1, compared with BA.1, and eight times lower for BA.4 and BA.5.
The latter echoes preliminary data from South Africa, which Ars reported on Monday. There, the researchers found that in unvaccinated subjects who recovered from BA.1 infection, neutralizing antibody levels were 7.6-fold and 7.5-fold lower against BA.4 and BA.5, respectively, compared to levels against BA.1. While vaccination with the Pfizer/BioNTech or J&J vaccine narrowed the gap in neutralizing antibody levels, researchers still saw a loss in protection: 3.6-fold and 2.6-fold levels of neutralizing antibodies against BA.4 and BA.5, respectively, compared with Bachelor’s degree 1.
Taken together, the data all suggest the possibility of more re-infections from the newer Omicron sub variants, particularly in unvaccinated or unvaccinated subjects. This could lead to more waves of infection in the US and around the world – although experts don’t expect another towering wave like the BA.1 increase in January.
It also raises concerns about second-generation vaccine designs – some of which may target BA.1, at least in part. For example, last month, Moderna has announced that it believes in a bivalent vaccineTargeting two copies of the virus in one shot would be a winning strategy to provide broader, longer-lasting protection.
“The latest bivalent enhancer candidate, mRNA-1273.214, which combines the currently authorized Moderna COVID-19 enhancer with [BA.1] Stéphane Bancel, Moderna CEO, said in a statement at the time that the Omicron booster candidate, remains our lead candidate for Fall 2022 in the Northern Hemisphere.
But, new data suggest that BA.1-based vaccines may provide poor protection against BA.2, BA.4, BA.5, and any other omicron sub-variants.
“Contrary to the time when omicron first appeared, subspecies of omicron have begun to target humoral immunity [antibodies and other adaptive responses] caused by omicron itself, including humoral immunity caused by omicron infection after vaccination, the authors of the new study from Beijing wrote. Not the ideal antigen to induce broad-spectrum protection against omicron emerging substrains. “
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