A recent study found that mRNA vaccines give protection against Omicron BA.2, however the protection against coronavirus infection and clinical sickness fades after the third dosage. This comes as the Omicron subvariant is fuelling a major COVID rise in regions of Asia and Europe, and scientists are attempting to figure out how severe the infections caused by it may be.
Subvariant BA.2 vs. Omicron BA.1
BA.2 is previously known to spread quicker than BA.1, however it was unclear if the subvariant is better at avoiding immunizations. “The worry was that BA.2 would be even worse than BA.1,” says Laith Abu-Raddad, an infectious-diseases epidemiologist at Weill Cornell Medicine–Qatar in Doha and a co-author of the research, as cited by the scientific journal Nature. The paper has not yet been peer reviewed and is available on the preprint portal medRxiv.
How much protection do BA.2 vaccinations provide?
The researchers discovered that participants who got two doses of either the Pfizer–BioNTech or Moderna mRNA-based vaccines experienced several months of significant protection against symptomatic sickness induced by either BA.1 or BA.2. However, protection diminished to roughly 10% after just 4–6 months, implying that the immunizations avoided only 10% of the instances that would have occurred if all of the participants had been unvaccinated, according to the Nature report.
It went on to say that protection against BA.2 did not appear to fade any quicker than protection against BA.1, and that a booster injection restored protection against symptomatic infection by either subvariant to 30–60%. Surveillance data from the United Kingdom show a similar pattern: vaccination efficacy against symptomatic COVID-19 is less than 20% for both subvariants 25 weeks or more after a second dose, but improves to around 70% 2–4 weeks after a third dose.
According to Abu-Raddad, the findings give him optimism since vaccinations prevent many of the severe COVID-19 cases, even when administered in response to BA.2. “Given the challenges of evolution, the vaccinations are actually performing surprisingly effectively,” he added.