COVID-19 vaccines are working, but 'now is not the time to relax,' Montreal infectious disease specialists say

Montreal -

Robert Zemnickis was surprised to learn he’d tested positive for COVID-19 given his double vaccination status.

As he lay in bed in late July battling a breakthrough infection, shivering, his face and eyes swollen and feeling too exhausted to get up, he said all he could think about was “Wow, I can’t believe how sick I got, and thank God I was vaccinated.”

The Montreal native who’s been living in Miami for decades conjectures that if he hadn’t been double vaccinated, it might have been much worse.

“I can’t imagine -- I would have definitely been hospitalized.”

As it was, he missed three weeks of work. After four weeks, the 55-year-old busy interior designer is still tired, has mild throat trouble, hasn’t regained his sense of smell or taste, and has a COVID-related flare-up of his rheumatoid arthritis.

Zemnickis said he’s been careful to protect himself and others. He suspects he caught the virus when he went to a birthday lunch at a restaurant with four other people.

“Of course, we weren’t wearing masks while we were eating,” he said.

His message to others: get fully vaccinated against COVID-19 and even afterward, remain cautious.

It may seem as though Zemnickis’s story has no bearing on the situation in Quebec. After all, he lives in an American state that, as of last week, accounted for one in five COVID-19 patients hospitalized nationwide, the Associated Press reported.

“We're hearing about the epidemic of the unvaccinated here,” Zemnickis said.

Only 55 per cent of eligible people living in the state of Florida are double vaccinated, according to data from the Florida Health Department. The Delta variant is running rampant.

In contrast, 78 per cent of the eligible population in Quebec aged 12 and up have already received two shots. However, the number of cases and hospitalizations is creeping higher.

As a result, Montreal experts say there are lessons to be learned from what’s happening south of the border, and excellent reasons why even those who are double vaccinated might want to reexamine their behaviour.

“Absolutely, we need to understand that we can't just rely on thresholds on herd immunity,” said Dr. Donald Vinh, an immunologist at the McGill University Health Centre (MUHC) and a member of the Canadian government’s COVID-19 Immunity Task Force (CITF).

Herd immunity thresholds need to be higher because the Delta variant is more transmissible, he explained.

“As we get there, we all need to do our part and stick with the public health measures of masking, distancing, and ventilation [indoors] until we get to at least 90 per cent [population vaccinated] or so, and then we can start scaling back,” he said.

“Now is not the time to relax, even if we're getting fatigued.”

YOU’RE NOT INVINCIBLE

It’s a difficult message to impart at a time when people who are double vaccinated are downloading their vaccine passports so they can partake in all sorts of non-essential activities as of Sept. 1.

It may feel like the gates to freedom have been thrown wide open: the vaccines are working, they’re keeping people out of the hospital, and vastly reducing the risk of dying, Vinh said.

“What we have consistently seen is that the disease part really gets muted quite dramatically,” by the vaccine, he said.

We know that the vaccines are at least 85 per cent effective in preventing that [severe] disease,” the clinician-scientist said.

It’s a protective effect that also appears to stand up to the Delta variant, even though there’s still much to learn about the variant itself. However, breakthrough infections can occur, even if they're rare.

Getting two doses of vaccine does not mean you’re a superhero, said Vinh.

“It's not a forcefield, right, it's not like you're wearing a shield around you that prevents you from being exposed to various particles in the air. You're still breathing,” he said, and there’s still a chance you’ll breathe in virus particles that someone else is breathing out.

HOW COMMON ARE BREAKTHROUGH INFECTIONS?

The rates of breakthrough infection vary, based on at least two key factors, said Vinh: how much COVID-19 is circulating — particularly, the more transmissible Delta variant — and testing strategies and reporting.

In the U.S., the Centres for Disease Control (CDC) defines a breakthrough infection as one that occurred 14 days after completing the vaccine series. From January - April 30, 2021, in the U.S. there were 10, 262 cases among 101 million vaccinated, a rate of about 0.01 per cent.

Among these cases, 706 people were hospitalized and 133 people died - a combined rate of 0.0008 per cent.

Since that period an additional 67 million people were double vaccinated, however, the CDC’s testing strategy and reporting changed, so the number of breakthrough cases is not known.

But the number of breakthrough cases requiring hospitalization was 7,887 and the number of deaths increased to 1,829.

So, among those fully vaccinated, the combined rate of breakthrough cases that required hospitalization or where deaths occurred is 0.006 per cent — a seven-fold increase.

In Quebec, the picture is significantly murkier right now. Vinh said he was unable to find data on breakthrough cases using the same definition as the CDC (at least 14 days after a second dose).

He suspects the frequency of breakthrough cases in the province must be low at the moment because, according to the provincial data available, people who now require hospitalization have either had no doses, one dose, or a second dose administered only in the last seven days).

But as the weather changes and people head indoors, more individuals could be affected. Cases will increase and likely so will the number of breakthrough infections, even if they remain uncommon overall.

As Quebec health minister Christian Dubé said at a press conference on Tuesday, “it’s back to school that worries us.”

BLAME THE DELTA VARIANT

There are two main reasons for even double vaccinated Quebecers to take reasonable precautions to prevent infection.

The first is the danger of transmission. The virus may result in no symptoms, or mild symptoms but the science on the highly contagious nature of the Delta variant is clear, said Vinh.

“If you are vaccinated, you can still have a certain amount of virus in your airway, what we call the viral load, at the beginning of the infectious process, as if you were not vaccinated,” he said.

“The thing about Delta is, because you have such a high viral load, and because it's more transmissible, you can imagine that these particles are coming out of your airway if you're infected and they will try and find susceptible people,” said Vinh.

“The reason it's going to do that is because if they can find them, then they can reproduce at a higher quantity.”

Susceptible people include those who only had one dose, children under 12 who are not eligible to get the vaccine, and people with health problems who are vaccinated but immunocompromised.

NO ONE WANTS LONG-COVID

The second consequence of catching COVID-19 is the now well-established, but less understood phenomenon of long-COVID symptoms.

According to Dr. Emilia Liana Falcone, an infectious disease specialist at Centre hospitalier de l'Université de Montréal (CHUM) and director of the post-covid clinic at the Montreal Clinical Research Institute, “patients who are asymptomatic, or who have mild symptoms during the acute phase can develop long-COVID symptoms.”

“We do see that there are symptoms that either will have a fluctuating course or will appear weeks after so just because there's nothing immediately after the acute infection doesn't mean there will be nothing,” the specialist said.

Those symptoms can include fatigue, lack of smell and taste, shortness of breath, muscle pain, brain fog and lack of concentration.

"We have seen patients now that are 12 to 15 months after infection who are still having persistent symptoms,” Falcone said.

“There's some data that's coming out now that shows that if you've had COVID infection, you’re actually at increased risk for having a heart attack or a stroke,” Vinh added.

Vaccines will effectively prevent the risk of serious disease and long-COVID symptoms, but Vinh likens the need for even double vaccinated people to stay in line with public health measures with how one builds a house.

“When you build a house you need different tools,” he said. “It's the same thing with keeping community transmission and the virus under control. We cannot rely exclusively on vaccination. Herd immunity is one tool, You also need all the other measures along the way, at the same time,” he said.

Only when the house is built and ready to go “can you start putting your tools back in the toolbox,” he said.

“But not before.”