The omicron subvariant BA.2 has many genetic differences from its parent strain that would warrant it being labeled as a separate variant of concern with its own Greek letter, Japanese researchers said in a study posted Feb. 15 on the medical preprint server BioRxiv.
The study, which has not been peer-reviewed, outlines the virological characteristics of BA.2 based on laboratory experiments conducted by several universities in Japan.
Five things to know:
1. Researchers found BA.2's reproduction number — or the number of cases directly caused by an infected individual throughout his or her infectious period — was 1.4 times higher than that of BA.1, the original omicron strain.
2. Similar to BA.1, the omicron subvariant appears to thwart vaccine-induced immunity, researchers said. However, COVID-19 vaccine boosters were found to reduce the risk of reinfection by about 74 percent, according to CNN.
3. Cell culture experiments found the subvariant replicated in nasal cells faster than BA.1 and was better at causing cells to stick together in large clumps that eventually become factories to produce more copies of the virus.
4. In hamster studies, subjects infected with BA.2 got sicker and had worse lung function than those injected with BA.1. While the findings suggest the subvariant may cause more severe illness than BA.1, more clinical research is needed to better understand severity, researchers said.
5. The findings highlight the BA.2's potential threat to global health and the importance of more closely monitoring the subvariant, researchers said.
"Based on our findings, we propose that BA.2 should be recognized as a unique variant of concern, and this SARS-CoV-2 variant should be monitored in depth," researchers said.