The Department of Medical Sciences has found that giving an mRNA-based vaccine as a booster after doses of old-technology vaccines like Sinovac and/or AstraZeneca produces a high level of immunity against both the Delta and Omicron coronavirus variants.

Department chief Dr Supakit Sirilak said data from a test involving 80 people showed that all Covid-19 vaccines produced low levels of immunity against Omicron when compared to Delta.

But immunity levels significantly increased after getting a mixed boosting dose, especially from an mRNA-based vaccine, Dr Supakit said.

"The study shows we do need to get a booster vaccine for fighting against the Omicron variant," he said.

"I would like to recommend all people, especially those considered at high risk from the disease, to get the booster vaccine as soon as possible."

The study looked at immunity levels against both variants two weeks after test participants got a booster shot.

Test results showed a very high level of immunity against the two variants.

According to the study, the level of immunity increased to 282.5 and 729.3 for Omicron and Delta respectively from two full doses of Sinovac followed by a booster shot -- using a smaller quantity -- of  Pfizer.

A similarly effective result -- 222.9 and 691.1 -- was produced by two full doses of AstraZeneca followed by a booster dose of Pfizer.

In contrast, two shots of the same vaccine produced low levels of immunity against the Omicron strain -- 23.81 for AstraZeneca and 19.17 for Pfizer. Combining two shots of vaccines using older technology -- Sinovac and AstraZeneca -- produced a level of just 11.63.