AstraZeneca covered 19 vaccine, asking its regulator Friday to assess it for a possible rollout.

Meantime, the Philippines and Thailand secured millions of doses, giving the shot a vote of confidence after experts raised questions about trial data earlier this week.

The U.

K government, which has secured 100 million doses of the vaccine, has targeted a rollout to begin before Christmas.

AstraZeneca's candidate is viewed as offering one of the best hopes for many developing countries because of its cheaper price and ability to be transported at normal fridge temperatures.

The Thai government signed a deal on Friday to procure 26 million doses of the vaccine, and officials in the Philippines said they would secure 2.6 million shots and we're negotiating a possible purchase of the further one million doses.

The announcements came after some scientists raised doubts about the robustness of results, showing the shot was 90% effective in a subgroup of trial participants who by error initially received a half does, followed by a full does.

AstraZeneca's CEO said on Thursday that the drug maker was likely to run an additional global trial to assist the efficacy off its vaccine using the lower dosage.

The company had released trial data on Monday that showed its experimental vaccine prevented on average, 70% of covert 19 cases in late stage trials in Britain and Brazil.

While the success rate was 90% in the subgroups, some experts said the relatively small number of participants made it harder to be confident in the findings.

AstraZeneca said the administering off the half dose has been reviewed and approved by independent data safety monitors and the UK regulator, adding the regulator publicly confirmed that there was no concern.