“At present there is no indication that an adjustment of our vaccine to circulating variants is necessary,” BioNTech chief Ugur Sahin said during an online shareholder meeting on Tuesday.

BioNTech was constantly reviewing the effectiveness of the shot against new variants, he said, in order to prepare in case a third vaccine dose or an adjustment of the jab were needed.

To facilitate this, BioNTech was using a “prototype approach,” Sahin said. Flexible processes in the areas of technology, production and authorization of the vaccines were also being developed.

Sahin said that there was more and more knowledge about the variants of the coronavirus. It had been observed that the immunity of vaccinated people declines with time and as new variants emerge, he said.

“I believe that a third vaccine to refresh immunity could be of high value,” Sahin said. “But we don’t know yet when and how often a booster shot will be needed.”

According to Sahin, the Mainz-based firm and its US partner Pfizer plan to produce 3 billion coronavirus vaccine doses this year, to be increased next year.

At least 50 per cent of the vaccines are to be produced by BioNTech itself.