Two New Omicron Variants, BA.4 and BA.5, Detected in the U.S. Suspected to Evade Immunity

Two New Omicron Variants, BA.4 and BA.5, Detected in the U.S. Suspected to Evade Immunity

Scientists haven’t scratched the surface of the most recent Omicron subvariant, BA.2. While some research exists to show that it is more transmissible than its mother strain, as proven by how wide it is sweeping in the U.S., we are not yet aware of how severe BA.2’s symptoms are. At the moment, there have been no official announcements attributed to a new surge because of the subvariant. 

So little is known about BA.2, and it looks like we’re not going to get the chance to study more about it. That’s because new and more relevant variants are coming to light, namely, BA.4 and BA.5. Both subvariants of Omicron, current predictions point to these two new strains being more transmissible than BA.2 and having the capability to evade immunity from vaccines and prior infection

BA.4 and BA.5 Already Present in the U.S.

Researchers have identified sequences of the BA.4 and BA.5 subvariants in multiple states. As of the final week of April, the international research database GISAID has identified 12 BA.4 cases dating back from March 30 and five BA.5 cases from March 29. 

While we know that the BA.4 and BA.5 variants are here, virologist Andy Pekosz says it is still not clear how widely they have spread in the country. According to the Centers for Disease Control and Prevention’s COVID Data Tracker, the Omicron subvariants BA.1, BA.2, BA.4, and BA.5 make up less than 1% of U.S. COVID cases.

Early Predictions on BA.4 and BA.5: Transmissibility and Immunity Evasion

Before being discovered in the U.S., the BA.4 and BA.5 subvariants swept widely across South Africa, which led to significant research from scientists in the region. In an interview, South African COVID expert Tulio de Oliveira said that the new subvariants seem to be more infectious than stealth Omicron (BA.2). This is attributed to its unique mutations, which also might allow it to evade immunity.

These initial findings lead to the speculation that BA.4 and BA.5 may cause another wave of reinfections and affect even individuals that have been vaccinated and boosted. This is the case today in South Africa where there is a surge of infections despite 90% of the population having some level of immunity from vaccines or prior infections. 

Scientists Doubtful that BA.4 and BA.5 Will Cause a Surge 

While the BA.4 and BA.5 variants have successfully taken over South Africa, U.S. scientists think that the situation will not play out the same in the U.S. According to COVID-19 researcher Madison Stoddard, there are stark differences between the South African and American populations in terms of contact patterns and the nature of immunity. 

Despite predictions that BA.4 and BA.5 have the capacity to evade vaccine immunity, U.S. health experts still encourage citizens to get vaccinated and boosted. Getting additional protection in the form of vaccines is much more reliable than only a prior infection. In addition, health officials are considering reinstating mask mandates to decrease the risk of exposure to both old and new COVID-19 strains. 

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