Portugal will give a third dose of the coronavirus vaccine to people aged 65 and older from next week, starting with the most vulnerable groups, such as care home residents and those over 80 years old, Reuters reports.

The southern European nation, which has the world's highest vaccination rate with 85 per cent of its total population fully jabbed, started last month to give an extra Covid-19 shot to those aged over 16 with weakened immune systems.

It is now extending it to everyone aged 65 and older starting Oct 11, the health secretary of state, Antonio Sales, said late on Monday. He said the booster could only be administered six months after people received their second dose.