PARIS: The AstraZeneca vaccine's rollercoaster ride has taken another twist with a growing list of countries restricting its use over "very rare" blood clots.
While Britain, whose Oxford University developed it, now no longer recommends it for the under 30s, South Africa has rejected it outright.
Nevertheless, the vaccine is still the most widely used in the world and remains cheaper and easier to store than its competitors.
It has already been given in some 111 countries - more than its competitors Pfizer-BioNTech and Moderna put together - according to an AFP database from official sources.
Here is an overview of where the jab is now being restricted:
South Africa suspended its vaccine rollout - meant to begin with AstraZeneca in February - after a study found the jab failed to prevent mild and moderate illness caused by a variant found there.
Instead it offered its doses to the African Union.
More than a dozen countries including the biggest European Union nations suspended AstraZeneca shots in mid-March because of fears over blood clots and other possible side effects.
Most then restarted using it after Europe's drugs regulator said it was "safe and effective".
But some other countries continued their suspensions, including Norway and Denmark.
Hong Kong said on Friday it had asked AstraZeneca to suspend delivery of its vaccine.
"We think it is not necessary for AstraZeneca to deliver the vaccines to the city within this year," said the city's health chief, adding Hong Kong wanted "to avoid any waste as vaccines are in short supply globally".
Many countries have resumed the vaccine's use only for older people, aged 55 and above, because the clots tend to affect younger people more.
These include France, Canada, Germany, the Netherlands, Finland, Iceland and Sweden.
But the doubts about blood clots did not go away, and the EU and British drugs regulators said Wednesday that it was linked to clotting in some rare cases.
Spain, the Philippines and Italy reacted by suspending the jab for people under 60 while Belgium restricted it to over 55s.
Australia says it should no longer be given to people under 50 unless they had already received a first dose without ill effects.
Oxford University has suspended trials on children following the new concerns.
Britain, which has already given more than 20 million doses of jab, says it will now offer alternative vaccines to young people.
France said on Friday that people under 55 who received a first dose of AstraZeneca's COVID-19 vaccine should receive a new-style messenger RNA (mRNA) vaccine for their second dose.
Two mRNA vaccines, one from Pfizer and BioNTech, and another from Moderna, have been approved for use in France.
MOST WIDELY USED
Despite criticisms over supply difficulties and safety concerns, the AstraZeneca vaccine is today being administered in around 111 countries and territories.
The jab also forms the bulk of those being given for free to poorer countries under the Covax scheme led by the WHO, the Gavi vaccine alliance and the Coalition for Epidemic Preparedness Innovations.