Two doses of Covid vaccines don't give adequate levels of protection against the Omicron variant, UK tests have found. 

However, scientists say booster doses 'significantly' increase protection and have advised on maximising coverage of third doses. 

The UK Health Security Agency stressed that a further follow-up will be needed to assess the duration of protection from booster vaccinations.

Their comments are based on findings from early analysis of Omicron and Delta cases and their effectiveness against the new variant.

Data indicates overall that vaccines are less effective at stopping the new variant.

A total of 581 Omicron cases and thousands of Delta cases were analysed in the findings. 

The Oxford-AstraZeneca and Pfizer vaccines showed drops in their effectiveness to offer protection against infection and mild disease. 

However, the third dose increased the protection against getting Covid symptoms to between 70 and 75%.

Dr Mary Ramsay, Head of Immunisation at the UKHSA, said: "These early estimates should be treated with caution but they indicate that a few months after the second jab, there is a greater risk of catching the Omicron variant compared to Delta strain."

"We expect the vaccines to show higher protection against the serious complications of COVID-19, so if you haven't yet had your first two doses please book an appointment straight away."