23 Jan 2023 • The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) BA.2.75 sublineage of the B.1.1.529 (omicron) variant may evade neutralising antibodies. In comparison to BA.4 or BA.5 reinfection, the effectiveness of prior infection against reinfection with BA.2.75.2 appears to be weaker. Pre-omicron-conferred immunity against omicron infection may not survive longer than around a year, according to this result, which also demonstrates that protection provided by a prior pre-omicron infection is insignificant at this point of the pandemic. When the prior infection was with a BA.1 or BA.2 subvariant, the protection provided by a prior omicron infection was moderate, at around 50%, but was higher when the prior infection was more recent, at about 80%. Pre-omicron and omicron infection-induced immunity was the most effective defence against BA.2.75 reinfection. It's possible that viral immune-system evasion has picked up speed recently in order to overcome high immunity throughout the world population, which hastens the waning of natural immunity.

Source: NEJM | Read full story