Moderna Inc said on Wednesday its COVID-19 vaccine booster that targets both the original coronavirus strain and Omicron produced a better immune response against the variant than its original vaccine.

The booster raised virus-neutralizing antibodies by eight-fold in a study. The vaccine was generally well-tolerated, with side effects comparable to a booster dose of mRNA-1273 at the 50 micrograms level.

"We are submitting our preliminary data and analysis to regulators with the hope that the Omicron-containing bivalent booster will be available in the late summer," Chief Executive Stephane Bancel said in a statement.

Shares of Moderna were up 2% in premarket trading.