Spain will start to administer the fourth dose of vaccine against Covid-19 on September 26, said the Ministry of Health.
The decision was made at a meeting of the Public Health Commission, which includes members from all 17 autonomous communities of the country, Xinhua news agency reported.
People aged over 80 and those who live in nursing homes will be the first to receive the second booster.
The ministry said the first batch of vaccines against the Omicron variant will arrive on Friday and will be distributed next week.
So far, more than 95 million doses of vaccine have been administered in Spain, with 40 million people having received two doses.