Ontario is immediately suspending the first doses of the AstraZeneca COVID-19 vaccine in “great caution” after a recent increase in rare blood clots, Chief Medical Officer Dr. David Williams said.
The move follows eight cases of vaccine-induced immune thrombotic thrombocytopenia (VITT) on Saturday among more than 650,000 doses administered since the province began using the AstraZeneca vaccine in early March.
Health officials said they would look at the data to determine further use of the vaccine and noted that information from the UK – where AstraZeneca has been used on millions of people – shows a “very high risk.” reduced ”blood clots in people receiving second doses.
There will likely be the option that people who received the first doses of AstraZeneca can receive second doses of the Pfizer or Moderna vaccines, Williams said, praising those who received the vaccine for doing their part to reduce. the spread of COVID-19 during other injections. were in limited supply.
The decision to suspend AstraZeneca was announced shortly on Tuesday afternoon as the science table informing the government released a research paper on the matter.
Public Health Ontario’s Dr Jessica Hopkins said the risk had recently increased to one case of vaccine-induced clots per 60,000 doses, compared to one in 100,000.
“This is an important safety signal that we don’t want to ignore,” she said in an online press conference.
With around 50,000 unused doses of AstraZeneca in Ontario, the hiatus is unlikely to hamper the government’s goal of getting 65% of adults to get their first shot of the vaccine by the end of May, given the increased supply. in Pfizer and Moderna.