The Ontario government is shortening the amount of time residents who received an initial dose of Oxford-AstraZeneca’s COVID-19 vaccine should wait before getting their follow-up shot.
The government had previously said AstraZeneca recipients should wait 12 weeks before getting a second shot, despite shortening the interval for all other vaccines.
But it amended the guidance this afternoon, joining other provinces in reducing the wait time to eight weeks.
The province now says those who received a first jab of the AstraZeneca vaccine should seek their second shot between eight and 12 weeks later, noting those residents can safely use any of the currently approved vaccines for their second dose.
The province had been facing growing pressure to shorten the interval, with mayors in one long-standing COVID-19 hot spot region saying residents should have the choice to seek full immunity sooner and acquire better protection against more infectious virus variants.
The province says AstraZeneca recipients will be eligible to book their second shots as of Monday at 8 a.m., noting those who want a second dose of the same vaccine must revisit the place where they received the first one. Residents who wish to switch to the Pfizer-BioNTech or Moderna vaccines as a second shot may book through the provincial portal.
“This decision is based on emerging clinical evidence about the administration of two doses of different vaccines, as supported by the National Advisory Committee on Immunization (NACI),” the province said in a statement.
“Evidence from multiple studies indicates that mixing of COVID-19 vaccines (receiving an mRNA vaccine after an AstraZeneca vaccine) at dosing intervals between eight and 12 weeks is safe and demonstrates a beneficial immune response.”
The province noted, however, that some evidence suggest waiting for a longer interval between AstraZeneca doses “provides higher protection.”
The news came as Ontario reported 502 new cases of COVID-19 on Saturday, along with 15 new virus-related deaths.
Health Minister Christine Elliott said 89 of the new infections were recorded in Toronto, 71 in Peel Region, 51 in Waterloo, 37 in York Region and 31 in Durham Region.
The numbers came from nearly 24,100 tests completed since the last daily report, she added.
Provincial data showed 447 people are in hospital due to COVID-19, including 422 in intensive care and 277 on ventilators.
The province said 195,032 doses of a COVID-19 vaccine were administered in the past 24 hours, for a total of 11,022,452 shots given so far.
Ontario entered the first stage of its economic reopening on Friday, clearing the way for restaurants to resume limited patio service, fitness classes to operate outdoors and non-essential retailers to re-open their doors to limited customer traffic.