The Oxford University-AstraZeneca COVID-19 vaccine has, along with Pfizer's jab, the greatest global reach, but the distribution has been stop-start among many countries, with investigations into whether there is any link with some rare blood clots.
International health regulators, notably the World Health Organization, have given it their backing. The European Medicines Agency has said it has not identified any risk factor in causing blood clots and the UK's regulator says the benefits of the vaccines against COVID-19 continue to outweigh any risks.
Here is a country-by-country take on the use of the AstraZeneca vaccine.
AstraZeneca is now to be used for people aged over 60 in Germany, while investigations continue into blood clots in some younger patients. "We have to be able to trust the vaccines," said Chancellor Angela Merkel. "And transparency is the best way to deal with such a situation."
The AstraZeneca vaccine is not being given out to people aged under 55 because of concern over blood clots internationally. So far, the AstraZeneca, Johnson & Johnson, Moderna and Pfizer-BioNTech jabs have been approved in Canada and with a population of 38 million it has ordered or reserved more than 400m doses of vaccines.
A third wave is threatening to overrun hospitals in France but at the same time there is a high level of doubt among the population over the AstraZeneca jab. France is one of the countries with the highest level of vaccine skepticism. Initially, the AstraZeneca vaccine was only approved for people aged under 65, but following the temporary suspension of the AstraZeneca jab on March 15, the age restriction has reversed and it is now only being given to people over 55.
Spain has now extended the delivery of the AstraZeneca jab to people aged over 65 following new assurances over its safety, it announced last Tuesday. Spain has been one of Europe's hardest-hit countries, with more than 75,000 deaths from COVID-19 and it has started to use the AstraZeneca jab again following advice from the EMA and the World Health Organization. It halted the use of the jab on March 15.
Prime Minister Mario Draghi was vaccinated on Tuesday with the AstraZeneca vaccine, showing his support for the jab. It had been suspended on March 15 but is now being given out to the public, with Draghi promising to ramp up vaccinations.
The jab has been suspended now until April 15, while more information is gathered over the possible risk of it causing blood clots. The distribution was stopped on March 11 over health workers suffering from clots after getting the vaccine.
Along with Norway, Denmark suspended using the AstraZeneca jab on March 11, initially for two weeks and now it will not be resuming its distribution until mid-April. Danish Health Authority director Soren Brostrom said: "Many studies have been launched, but we do not yet have any conclusions, which is why we have decided to extend the suspension."
It suspended use of one batch of the vaccine on March 7 after the death of one person and another becoming ill. That batch was shipped to 17 EU countries. Austria is now giving out the vaccine to all age groups.
A decision was made on March 15 to suspend the use of the vaccine as a precaution and now it is only being given to those aged over 65.
The use of the AstraZeneca vaccine was suspended on March 19 while investigations into possible blood clots take place. Since March 24 it is only being given to people aged over 65.
The vaccine is yet to be approved in Switzerland, where its authorities say it requires more data.
Distribution of the vaccine was stopped on March 15 but it has started again after the EMA said it was safe to use.
A decision was made to stop use of the vaccine on March 14 following reports of serious blood clotting in Norway but it started again after finding no suspicious cases of blood clotting in those people vaccinated.
The vaccine was suspended on March 15 following reports of serious side effects but it is now being used again.
Vaccinations are being given out to everybody. A batch linked to a death in Austria was not used and then vaccinations were temporarily halted on March 15 pending advice from the EMA.
A decision was made to suspend the vaccine distribution on March 15 but it was restarted four days later.
Along with many other European countries, distribution was stopped on March 15 but it has since started again.
Distribution of the AstraZeneca jab was stopped on March 15 but began again following EMA advice.
Distribution of one batch of the vaccine that was linked to the death in Austria wasn't used but otherwise the jab has been given out to all age groups without interruptions.
Vaccine distribution began again on March 19 after the head of the Bulgarian medicines agency said an investigation into the death of a woman hours after she got an AstraZeneca shot did not establish a direct link to the inoculation. The distribution had stopped on March 12.
The use of the vaccine was stopped on March 11 due to "extreme caution" but is now being used again.
Vaccinations were stopped on March 11 and now they are being given only to those over aged 70.
Vaccinations using AstraZeneca are being carried out after being briefly stopped on March 15 due to concerns over safety. Senior politicians have been given the jab to boost public trust in the vaccine.