TOKYO: Existing novel coronavirus vaccines are likely to be effective to some extent against the omicron variant of the virus, a Japanese expert said, stressing the importance of third COVID-19 vaccine shots.

On Wednesday, Japan started giving booster shots to medical workers aged 18 or older who had received second doses at least eight months before in principle, at a time when the omicron variant is spreading globally.

As the omicron strain has many mutations on its surface protrusions, called spike proteins, it is believed to be difficult for antibodies produced by existing COVID-19 vaccines to prevent omicron from entering cells in the human body, sources familiar with the situation said.

“As the omicron variant is a type of the novel coronavirus, existing COVID-19 vaccines, including the one manufactured by U.S. drug giant Pfizer Inc., are expected to be effective to some degree,” Tokyo Medical University professor Atsuo Hamada said.

“It is difficult to foresee how effective the existing vaccines are in preventing infections and the onset of illnesses, but I believe that they have effects in forestalling severe symptoms,” Hamada added.

He also said that a sixth wave of infections may occur in Japan between December and January.

As a mutant strain tends to spread in Japan some three months after overseas, the delta variant is likely to be the main cause of the possible sixth wave, he said.

“Omicron is not expected to become the main strain until after that,” he said.

“In any case, it is important to prepare for the expected spread of infections in the winter by promoting third COVID-19 shots swiftly,” Hamada said.

JIJI Press