Should fully vaccinated in Ontario mean three doses?

As restaurants, bars, gyms and other venues reopen to half-capacity on Monday, the Omicron variant is still spreading, and some doctors and scientists say it’s time for the official definition of “fully vaccinated” against COVID-19 to change.

With growing evidence showing that three doses are better at protecting against symptomatic infection from Omicron, as well as serious outcomes such as hospitalization and death, there are calls for the province to require individuals to get three shots to qualify as fully vaccinated.

Ontario’s downloadable vaccine certificate, needed to enter indoor spaces, currently requires two doses of Pfizer, Moderna or AstraZeneca, or a combination of these vaccines.

But public health guidance shifted just before Christmas, and now all adults are encouraged to get a third shot of an mRNA vaccine. It’s time for the definition of fully vaccinated to shift as well, said Dr. Peter Jüni, scientific director of the Ontario COVID-19 Science Advisory Table.

“I think it’s really important to understand, the window of opportunity is very short,” he said. “We need to react swiftly if we want to have a safeguard now with this reopening, which is a challenging next step.”

Jüni said the definition of fully vaccinated should change in mid-February to three doses, or two doses if less than three months have elapsed since the second shot, which would give people “some leeway” to make the transition.

“We’re in the middle of the Omicron wave and things will change over time with more and more people getting immune, either through third doses, or through infection,” he said. “Things will eventually slow down, we’re just not quite sure when this will be.” He added that a third dose is roughly 60-70 per cent effective against infection.

This is all the more important, Jüni added, with the arrival of the new subvariant of Omicron in Canada, known as BA.2. According to emerging data out of Denmark, it may be even more contagious than Omicron, but there is no evidence that it’s more severe.

Adding to the growing evidence on the efficacy of third doses, a pre-print study (not yet peer-reviewed) posted online Friday by researchers with Public Health Ontario and ICES, formerly the Institute for Clinical Evaluative Sciences, found a third shot was about 61 per cent effective against transmission of Omicron and 95 per cent effective against severe illness or death.

This debate over what constitutes the definition of fully vaccinated is not limited to Canada. Many countries around the world are weighing the merits of changing the definition or have already done so.

Last fall, Israel created new rules around vaccination status, requiring three doses for citizens to obtain a green pass, which allows entry to public indoor areas such as restaurants and gyms. In Austria, citizens with two doses are considered fully vaccinated only for nine months after their second shot. Singapore recently announced that people will lose their fully vaccinated status after 270 days unless they get a booster. And late last December, Dr. Anthony Fauci, chief medical adviser to US President Joe Biden, said officials in that country were not against reconsidering the definition but offered no timeline.

Back in Ontario, the chief medical officer of health, Dr. Kieran Moore, said at a Thursday press conference that a change to the definition of fully vaccinated would be a “government decision” that he could present options on, but he is awaiting guidance from Health Canada.

“It’s clearly an open policy window at present,” Moore said.

Both the Public Health Agency of Canada and the US Centers for Disease Control and Prevention continue to define fully vaccinated individuals as those who have received two doses of the Pfizer, Moderna or AstraZeneca vaccines, or at least one dose of Johnson & Johnson.

“But we will be examining – re-examining those kinds of policies going forward,” said Dr. Theresa Tam, Canada’s chief public health officer, at a recent press conference.

“Now is not the right time” to change this, she said, “because not everybody has had the chance to get that additional dose or getting up to date, not in Canada and certainly not globally.”

As of Friday, 6,258,119 Ontarians have received a booster dose, representing about 53 per cent of the eligible population. But third-dose vaccination rates vary drastically among regions and neighborhoods, with many of Toronto’s and Peel’s most marginalized communities seeing third-dose uptake still below 20 per cent, while affluent areas have rates above 50 per cent. Overall, more than 80 per cent of Ontarians aged 70 and older have received a third dose.

Dr. Zain Chagla, an associate professor at McMaster University and an infectious diseases physician, noted that the “huge inequities” in third-dose rates create problems with changing the definition of fully vaccinated.

“To exclude people based on the fact that they’ve only gotten two versus three shots, there’s a lot of issues there,” he said.

Chagla said that vaccine outreach, through ideas like community ambassadors, is a more “positive” way to encourage people than mandates, and there’s much more of that to be done around third doses.

“I think we got more vaccine uptake for sure with the vaccine mandate, but it did come at the cost of really pushing a lot of people against the medical system,” he said, as this approach bred some distrust.

“We can only play that card for so long, before it blows up.”

Dr. Amit Arya, palliative care lead at Kensington Health, notes the common practice of referring to a third shot as a booster implies it offers optional protection, which would be a mistake to assume.

“For a young and healthy person who perhaps has a lower risk at baseline of being hospitalized or being in the ICU, we know that two doses is still likely sufficient to keep you out of the hospital and especially keep you from being critically ill. But three doses is what you need for symptomatic protection from Omicron, ”he said.

When it comes to seniors, Arya said the risk of death is higher, especially for those who live with a disability or a chronic life-limiting illness, with just two doses.

Dr. Samir Sinha said continuing to use the term fully vaccinated for two doses is a “huge disservice” not only to seniors who derive enormous benefit from three doses, but people of all ages, “who do not know how essential and important a third dose is.” Sinha is director of geriatrics at Sinai Health and University Health Network.

“It speaks to a) the importance of clear messaging, and b) the importance of really making sure our hardest-to-reach individuals are appropriately reached by sending them a letter, giving them a phone call, literally knocking on their door.”