UPDATE 1-Quebec stops offering first doses of AstraZeneca vaccine

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TORONTO, May 13 (Reuters) - The Canadian province of Quebec will no longer offer first doses of the AstraZeneca COVID-19 vaccine as of Thursday, but will offer second doses using current supplies and future deliveries, the province's health ministry said in a release.

Most provinces made similar announcements on Monday and Tuesday, mainly citing concerns about supply, though officials in Ontario and Nova Scotia said the move was also based on a rise in the incidence of rare blood clots linked to the vaccine.

Canada's vaccine supply has expanded significantly in recent weeks, mostly thanks to shipments from Pfizer. The country has distributed just over 20 million doses of various COVID vaccines, and 11.6% were AstraZeneca's vaccine.

Officials have said that people who received the AstraZeneca vaccine may be offered a second dose of another vaccine, an approach that is being studied in the United Kingdom and has been allowed in Germany since early April.

Even so, Canada is due to receive 655,000 doses of a version of the AstraZeneca vaccine made by the Serum Institute of India this month, through the global vaccine buying system COVAX.

The country's decision to accept doses from COVAX has drawn criticism, as COVAX is the only way for many low-income countries to buy vaccines, and badly short of doses to distribute. Serum has cut exports in the face of a catastrophic surge of cases in India.

Officials in Ontario said on Monday that roughly one in 60,000 people who received the vaccine in the province developed the complication, which involves blood clots accompanied by a low level of platelets, cells in the blood that help it to clot.

Officials have linked three deaths to the AstraZeneca vaccine in Canada.

Regulators and expert groups in Canada, Australia, the United Kingdom and Europe had previously estimated that the risk was between one in 95,000 and one in 130,000.

Health Canada says those who receive the vaccine should seek medical attention immediately if they experience shortness of breath, chest pain, leg swelling, persistent belly pain, neurological symptoms like severe headaches or blurred vision, or skin bruising or tiny blood spots under the skin beyond the site of the injection. (Reporting by Allison Martell, Editing by Franklin Paul and David Gregorio)