Who gets sick? Report sheds new light on breakthrough cases and vaccine protection against hospitalization

As Ontario tries to contain a resurgence of COVID-19 cases, new data from Public Health Ontario shows that only nine fully vaccinated people under 60 have ended up in the ICU.

The report paints the most detailed picture to date of breakthrough cases – and those who become very ill despite being fully vaccinated – showing that the majority of those requiring hospital care are adults over the age of 60, with the highest percentage in their 80s.

Experts say the findings underscore that vaccines work well to prevent infections and hospitalizations. But they also support opening up third doses of the COVID vaccine to more older adults, highlighting why masking and other public health measures are still critical to protecting the most vulnerable at this stage of the pandemic.

“It’s clear that vaccines work phenomenally well,” said Dr Isaac Bogoch, an infectious disease expert and former member of Ontario’s now-disbanded vaccine task force.

“But if you look at all the breakthrough cases, the older age cohorts are more likely to have more serious infections.” Based on this and data from other parts of the world, “it would make sense to extend the eligibility for the third dose to the 50-year-old cohort and above.”

Third doses have been widely opened up in the US and Israel, but in Ontario only a few groups qualify, including health professionals, individuals 70 and older, those who received two doses of AstraZeneca or one dose of Johnson & Johnson, and First Nations, Inuit and Métis adults. You must be 168 days after your second dose to receive a third dose. Immunocompromised people, transplant recipients, patients with hematologic cancers, and seniors living in community settings such as long-term care facilities, retirement homes, and First Nations aged care lodges are also eligible.

The Public Health Ontario report, which includes COVID vaccination and case data up to Nov. 14, shows that there were only 17,596 breakthrough cases of the 11.1 million individuals who received two doses of the vaccine. As of Nov. 14, there were only 40 cases after a third dose, the data shows.

“The message is that the COVID-19 vaccines … are very effective in protecting against infection, and especially effective in protecting against serious consequences, including hospitalization and death, of 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 percent of Ontario’s COVID cases, with breakthrough infections accounting for 3.8 percent of cases. Public Health Ontario defines a breakthrough as “individuals who received two doses of a COVID-19 vaccine and became infected more than two weeks after receiving their second dose,” Wilson said.

The report notes that a similar trend was observed for COVID hospitalizations and deaths “with unvaccinated cases accounting for 90.9 percent of hospitalizations and 90.2 percent of deaths, while breakthrough cases accounted for 2.7 percent of hospitalizations and 3.3 percent of deaths.” On November 14, 178 fully vaccinated people had died of a COVID infection.

While the data shows that older adults are more at risk of hospitalization from a breakthrough infection — especially those over 80 — the number of “hospitalizations was higher in unvaccinated individuals compared to fully vaccinated individuals.”

Wilson said the data makes clear that the risk of COVID infection is higher for those who have not been vaccinated. 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 received two doses.

dr. Zain Chagla, an associate professor at McMaster University, said just nine intensive care unit admissions in people under 60 are “pretty remarkable”, but the “opposite side of the coin is that those over 60 are likely to need booster doses.” .”

Especially since the global vaccine supply is still under pressure and there are people in some countries who still don’t have access to the first and second doses, “you want to make sure that (third doses) are used in people where they get the most benefit.”

Lucy Gerardi, who will soon be 68, would be first in line if the third dose opened up for her age group.

“You just want to have that extra sense of security,” said the retired biology teacher and Oakville resident. Tuesday will be 168 days since her second shot, and she’s been calling around public health officials trying to get more information about when she might get a third chance, but to no avail.

“You’re just kind of in the dark,” Gerardi said.

“But I think we should be thankful that we have at least two shots when there are people in the world who don’t have one.”

According to Department of Health spokesman Bill Campbell, nearly 420,000 third doses have been administered in Ontario, up from 290,000 last week. These figures will be publicly reported shortly. “Ontario’s plan is to gradually expand booster eligibility for all Ontarios over time,” he said in an emailed statement. For now, in line with the recommendations of the National Advisory Committee on Immunization (NACI), they are being offered to vulnerable populations, Campbell added.

While Ontario data shows that COVID vaccines work very well, they still don’t provide complete protection, said Dr Abdu Sharkawy, an infectious disease specialist at University Health Network.

“The message distilled from this report shouldn’t 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, especially masking and minimizing risks associated with crowded, poorly ventilated indoor spaces, is still critical, even with a highly immunized population, Sharkawy said.

“We must remain vigilant about those things that can prevent people at risk from getting sick. And that means avoiding the possibility of a breakthrough infection by not relying on the vaccines alone.”

Wilson said Public Health Ontario will publish further reports on breakthrough infections “that could be used to inform the rollout of the third dose” and that researchers are looking at data on different age groups and time of infection after a second dose.


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