Serious breakthrough cases rare, data shows
COVID vaccines working ‘phenomenally well,’ but booster shots critical, experts say
As Ontario tries to keep a resurgence of COVID-19 cases under control, new data from Public Health Ontario shows only nine fully vaccinated people under 60 have ended up in the ICU.
The report paints the most detailed picture yet of breakthrough cases — and who is getting very sick despite being fully vaccinated — showing that the majority of those who need hospital care are adults over the age of 60, with the highest proportion in their 80s.
Experts say the findings underscore that vaccines are working well to prevent infections and hospitalizations. But they also support opening up third doses of the COVID vaccine to more older adults, and highlight why masking and other public health measures are still critical at this stage of the pandemic to protect the most vulnerable.
“It’s clear that vaccines are working phenomenally well,” said Dr. Isaac Bogoch, an infectious disease expert and a former member of Ontario’s now disbanded vaccine task force. “But if you look at all the breakthrough cases, there is a greater probability that the older age cohorts will have more serious infections.”
Based on this and data from other parts of the world, “it would make sense to expand third dose eligibility to the 50-year-old age cohort and up.”
Third doses have been opened up widely in the U.S. and Israel, but in Ontario only a few groups qualify, including health-care workers, individuals 70 and up, people who got two doses of AstraZeneca or one dose of Johnson & Johnson, and Indigenous, Inuit and Métis adults. You have to be 168 days past your second dose to get a third one. Immunocompromised people, transplant recipients, patients with hematological cancers, and seniors living in congregate settings, such as long-term-care homes, retirement homes and First Nations elder care lodges, are also eligible.
The Public Health Ontario report, which includes COVID vaccination and case data up until Nov. 14, shows there were only 17,596 breakthrough cases out of the 11.1 million individuals who have completed two doses of the vaccine. As of Nov. 14, there were just 40 cases following a third dose, the data shows.
“The take-home message is that the COVID-19 vaccines ... are highly effective at protecting against infection, and particularly effective at protecting against serious outcomes, including hospitalization and death, from COVID-19,” Dr. Sarah Wilson, a public health physician at Public Health Ontario, said in an email to the Star.
As of Nov. 14, unvaccinated individuals made up 91 per cent of COVID cases in Ontario, with breakthrough infections accounting for 3.8 per cent of cases. Public Health Ontario defines a breakthrough case as “individuals who have received two doses of a COVID-19 vaccine and were infected more than two weeks after receiving their second dose,” Wilson said.
The report notes a similar trend was observed for COVID hospitalizations and deaths “with unvaccinated cases accounting for 90.9 per cent of hospitalizations and 90.2 per cent of deaths while breakthrough cases accounted for 2.7 per cent of hospitalizations and 3.3 per cent of deaths.” As of Nov. 14, 178 fully vaccinated individuals had died of a COVID infection.
While the data shows older adults are more at risk of hospitalization from a breakthrough infection — particularly those over the age of 80 — the rate of “hospitalizations was higher among unvaccinated individuals compared to fully vaccinated individuals.”
Wilson said the data makes it clear the risk of COVID infection is higher for those who are unvaccinated. For those 60 and older, the risk of being hospitalized with the virus was about 16 times higher for unvaccinated individuals compared to those who had two doses.
Dr. Zain Chagla, an associate professor at McMaster University, said only nine intensive care unit admissions in people under 60 is “pretty remarkable,” but the “opposite side of the coin though is those over 60 probably do require booster doses.”
Especially since global vaccine supply is still strained and there are people in some countries who still don’t have access to first and second doses, “you want to make sure (third doses) are used in people where they’re going to derive the most benefit.”
Lucy Gerardi, who turns 68 soon, would be first in line if third doses were opened up for her age group.
“You just want to have that extra sense of security,” said the retired biology teacher and Oakville resident.
As of Tuesday, it has been 168 days since her second shot and she’s been calling around to public health officials trying to get more information about when she can get a third, to no avail.
“You’re just kind of in limbo,” Gerardi said.
“But I guess we should be thankful we at least have two shots, when there are people in the world that have none.”
Nearly 420,000 third doses have been administered in Ontario, according to Ministry of Health spokesperson Bill Campbell, up from 290,000 last week. These numbers will start being reported publicly soon. “Ontario’s plan is to gradually expand eligibility for a booster dose to all Ontarians over time,” he said in an emailed statement. For now, in line with National Advisory Committee on Immunization (NACI) recommendations, they are being offered to vulnerable populations, Campbell added.
While the Ontario data shows COVID vaccines work very well, they still do not offer complete protection, said Dr. Abdu Sharkawy, an infectious diseases specialist at University Health Network.
“The message that is distilled from this report should not be one of nihilism, that vaccines just don’t work well enough,” he said. “The vaccines work very well, but they have their limitations.”
That’s why maintaining public health measures, particularly masking and minimizing risks that come with crowded, poorly ventilated indoor spaces, is still critical, even with a highly immunized population, Sharkawy said.
“We have to maintain a sense of vigilance around those things that can prevent at-risk people from becoming sick. And that means preventing the possibility of breakthrough infection by not simply relying on the vaccines alone.”
Wilson said Public Health Ontario will be publishing further reports on breakthrough infections “that could be used to inform third dose rollout” and that researchers are looking at data on different age groups and the timing of infection after a second dose.