Booster shots to extend the protection of COVID-19 vaccines may be unnecessary for many people, a leading scientist behind the AstraZeneca vaccine said on Friday.

Oxford University Professor Sarah Gilbert told The Telegraph newspaper that immunity from the vaccine was holding up well — even against the delta variant. While the elderly and those who are immune-compromised may need boosters, the standard two-dose regimen is providing lasting protection for most people, she said.

“We will look at each situation; the immuno-compromised and elderly will receive boosters,” she said. “But I don’t think we need to boost everybody. Immunity is lasting well in the majority of people.”