Vaccine effectiveness against the Omicron variant is "significantly lower" than with the Delta variant but a booster dose raises protection against mild cases, a new study has found, Trend reports citing Euronews.
Research released on Friday by the UK Health Security Agency found that a full two-dose vaccination course was less effective against symptomatic disease with Omicron than with the original strain of COVID-19 or the Delta variant.
It found however that "moderate to high vaccine effectiveness against mild infection of 70-75% was seen in the early period after a booster dose."
Omicron was designated a variant of concern by the World Heath Organisation (WHO) in late November over concerns its high number mutations could make it more transmissible and more resistant to current treatment, including vaccines.
The variant, which was first detected by South African laboratories, has now spread to nearly 60 countries worldwide. Almost all of the nearly 2,200 confirmed cases of Omicron have however so far been either asymptomatic or mild.