Health officials in South Korea have approved the country’s first domestically developed Covid-19 vaccine for people aged 18 and over, adding another public health tool in the fight against the prolonged pandemic.

In clinical trials involving some 4,000 participants in South Korea and five other countries, SK Bioscience’s two-dose SKYCovione vaccine appeared to be more effective than the broadly used AstraZeneca jabs in building immunity against infections, officials at South Korea’s Food and Drug Safety Ministry said.

It was not immediately clear how officials will administer the newly developed vaccine or how big a role it will have in the next phase of the pandemic.

The vaccine was designed for the original version of coronavirus, not the more transmissible Omicron variant which wreaked havoc in the country earlier this year.

US giants Pfizer and Moderna have been speeding up their development of booster vaccines targeting Omicron and experts say it is possible the virus could evolve again in the coming months.

South Korea’s mass immunisation campaign has been mainly dependent on Pfizer and Moderna’s mRNA vaccinations. But officials say protein vaccines like SKYCovione, which are similar to those used for years against the common flu and hepatitis B, could appeal to people who are hesitant to use vaccines developed with newer technologies.

Food and Drug Safety Minister Oh Yu-kyoung said in a briefing: “The approval (of SKYCovione) internationally confirms the abilities of our companies to develop Covid-19 vaccines.”

She added that SK Bioscience is seeking an approval from the World Health Organisation for its vaccine, which would potentially open export opportunities.

South Korea has eased most of its virus restrictions after battling an Omicron surge earlier this year, but some experts say the country may see another rise in infections despite a high vaccination rate because of waning immunity and the possible emergence of new variants.

The country reported 10,463 new cases of the coronavirus on Wednesday, its first daily increase over 10,000 in 20 days.

Health Ministry official Son Youngrae said during a separate briefing that it is too early to tell whether the country is facing another surge after a months-long downward trend.