Experts caution numbers of fully-vaccinated in hospital present 'skewed' version of reality

On the surface, the numbers appear alarming.

During first two weeks of October, statistics from the BC Centre for Disease Control show nearly a quarter of people hospitalized for COVID-19 in the province were fully vaccinated.

That appears to be sharply higher than just a month earlier.

During the week of Sept. 10, for example, fully vaccinated people represented just 13 per cent of COVID-19 hospitalizations.

But experts say to understand what the numbers actually mean about your risk of a breakthrough case that lands you in hospital, you have to look at rates within the population, rather than the raw data.

“It exists only because so much more of the population is vaccinated,” said cardiologist and epidemiologist Dr. Christopher Labos.

“So when you just look at the raw numbers, you get a skewed version of reality,” Labos said.

Labos explained that because vaccines aren’t a perfect “shield” against infection, as more and more British Columbians are fully vaccinated, more and more will become infected with COVID-19 and end up hospitalized.

“Over time we should fully expect that the percentage of people in hospital that are fully vaccinated is going to go up, because there’s just going to be more of them,” Labos said.​

Dr. Brian Conway, medical director of the Vancouver Infectious Diseases Centre, pointed out that those that are older and also at risk of disease are over-represented within the doubled-dosed group, which means the data has to be age adjusted to create a true picture of risk.

“When we adjust things for age, it reassures me, it is affecting those who we knew to be at risk of serious disease since the beginning of the pandemic,” Conway said.

Taking the same data from the first two weeks of October, the hospitalization rate for those fully vaccinated is 2.3 people for every 100,000.

The rate for those partially vaccinated is 10.4 people for every 100,000.

And for those not yet vaccinated, it soars to 51.3.

Put another way, and widening out to cover the span of a month, data from the BCCDC shows those who are unvaccinated are roughly 10 times more likely to be infected with COVID-19, 52 times more likely to be hospitalized, and 44 times more likely to die, than British Columbians who are fully vaccinated.

“The vaccines clearly and unequivocally have helped reduce the rates of COVID-19,” Lobos said.

A recent analysis from the BCCDC found two doses of any COVID-19 vaccine was approximately 95 per cent effective against hospitalization.

Even so, Conway expressed concern over his expectation that both older people and those more at-risk for serious disease will continue to account for an increasing proportion of serious COVID-19 cases.

“We need to vaccinate the unvaccinated as soon as we can. We need to consider third shots in more people in a targeted way,” Conway said, adding that arguments could be made for offering a booster to anyone 65 years or older, or those those had their second dose at least six months ago.

Last Thursday, provincial health officer Dr. Bonnie Henry noted her team was watching breakthrough cases carefully, and digging through new data and evidence around who should be getting boosters next.

“We’ll have more to say about that soon, but that is the one of the things we’re looking at in some detail,” Henry said.