Here are the options countries are considering:

UNITED STATES: Booster shots will be made widely available from Sept 20 to Americans who received their initial two-dose Covid-19 vaccines made by Moderna and Pfizer at least eight months earlier.

BRITAIN: Officials recommend vulnerable people, front-line health staff and those aged over 50 be offered booster shots.

CHINA: By end-October, China is expected to complete giving regular regimen doses to 1.1 billion people and booster shots to limited groups such as the elderly and high-risk employees.

GERMANY: Government will offer booster shots to vulnerable people, such as the elderly and those with weak immune systems this month. The shots will be mRNA vaccines from Pfizer-BioNTech and Moderna regardless of earlier doses.

INDONESIA: Country started giving Moderna booster shots to medical workers in July and is considering extra doses for wider use.

ISRAEL: Booster shots offered last month to anyone fully vaccinated; the age of eligibility lowered to 12.

SINGAPORE: Only two groups of people are being offered booster shots for now: those aged 60 and above, and the immunocompromised.

THAILAND: Plans to give AstraZeneca or mRNA booster shots to an estimated 3.4 million people who received the Sinovac vaccine earlier.

REUTERS