No neutralization efficiency with two doses of the Pfizer vaccine was found against the omicron variant, assessed more than 5 months after receiving the second dose.
The third dose of the Pfizer vaccine efficiently neutralized infection with the omicron variant (neutralizing antibody titer, 1.11 after the second dose vs. 107.6 after the third dose).
The importance of a third vaccine dose is clear, owing to the higher neutralization efficiency against the omicron variant after the third dose. The durability of the effect of the third dose of vaccine against Covid-19 is yet to be determined.
Among the available monoclonal antibodies, Sotrovimab is most effective, although the concentration required to halve viral replication was roughly three times higher for the Omicron variant than for other coronavirus variants.
Recent analysis from the UK Health Security Agency suggests that the window between infection and infectiousness may be shorter for the Omicron variant than the Delta variant.
Data from recent outbreaks of Omicron demonstrate that the incubation period of Omicron may be as short as 3-5 days (compared to 5-7 days for the Delta variant and 7-14 days for the original SARS-CoV-2).