Even those who fell ill with the first subvariants of Omicron may not be safe from its subsequent mutations. This is confirmed by the data from South Africa , reports ArsTechnica.

Now the country is at the beginning of a new wave of disease. It is dominated by two sub-variants – BA.4 and BA.5. Despite the huge incidence of the first sub-variant BA.1 in December, the incidence of Omicron has increased by 269% in the last two weeks. Hospitalizations also increased, and mortality increased by 18%.

Preliminary data published last week explains the increase in the number of cases. Sub-variants of Omicron BA.4 and BA.5 avoid neutralizing antibodies that are formed after being sick with BA.1. 

Researchers in the lab contrasted neutralizing antibodies from people infected with BA.1 with sub-variants BA.4 and BA.5. They had samples from 24 unvaccinated people who had BA.1. and 15 vaccinated people who also fell ill. In the unvaccinated, the level of neutralizing antibodies was 7.6 and 7.5 times lower for BA.4 and BA.5, respectively, compared to the first subvariant. Among those vaccinated, the level of protection decreased by 3.6 and 2.6 times, respectively.

Preliminary data suggest that the new sub-variants avoid the protection that has developed after the disease on previous versions of the virus. Vaccinated people are better protected from it – but in regions with a small number of vaccinated Omicron may keep provoking new waves of disease such as the one that continues today.