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

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.”

Gilbert said the world’s priority should be to get more vaccines to countries that have received limited supplies.