Public health protocols helping keep breakthrough COVID-19 cases down, says Strang

As Nova Scotia prepares to roll out COVID-19 booster shots for long-term care residents and people who are immunocompromised, the province's chief medical officer of health says efforts to date have helped keep breakthrough cases to a minimum.

"We're keeping the circulation of COVID virus well under control, and so we're not having a major issue about large numbers of breakthrough cases," Dr. Robert Strang told CBC News on Tuesday.

Breakthrough cases are situations where someone gets COVID-19 even after being fully vaccinated. It's not unexpected, because no vaccine is 100 per cent effective. For the week of Oct. 7-13, for example, 24 of the province's 77 new cases were breakthroughs.

Strang said the chance of severe disease is reduced among people who've had both shots. Being fully vaccinated also lowers the likelihood of transmitting the virus to others while infected.

Breakthrough cases can lead to death

Still, breakthrough infections can be fatal, as seen this week with the death of former U.S. secretary of state Colin Powell.

Strang said there are often other factors at play, including a person's age and underlying health conditions.

Powell, for instance, remained vulnerable to the virus because of his advanced age and history of cancer.

"Those who are older, especially if they're older and [have] underlying chronic conditions, are less likely to respond optimally to the vaccine," said Strang.

It's why he believes there is an extra obligation for younger, healthier people to get their vaccines.

"To me, what that means is that all the rest of us need to recognize that there are people in our communities who, despite themselves being vaccinated, need an extra layer of protection around them by everybody else being vaccinated," he said.

Vaccine efficacy

Dr. Lisa Barrett, an infectious disease expert from Dalhousie University, said the introduction of third doses has some of the general population questioning the efficacy of COVID-19 vaccines after six months.

She said it's normal for effectiveness to wane, but there's no need to worry yet.

"The information and data from around the world [is] looking like your protection against hospitalization and death — even if you had very close together, early doses — remains good," Barrett told CBC Radio's Mainstreet on Tuesday.

The effectiveness of vaccines to prevent infection does appear to wane over time, she said, but they continue to help protect people from getting too sick if they do catch the virus. Barrett added the vaccines weren't designed to completely prevent infection, which can explain breakthrough cases.

"They're meant to prevent the really bad impact of infection like death and hospitalization, as well as lots of spread to other people in our communities," she said. 

"They're still doing that, but in breakthrough cases, we know that people who get very sick or die often have other underlying medical issues and or have been in a situation where they've been exposed to a very high dose of the virus."

More breakthrough infections expected

As the province's vaccination rate increases, Strang said the percentage of new cases that are breakthroughs will also increase. But one of the reasons Nova Scotia isn't seeing the increase in breakthrough cases that some other provinces, such as New Brunswick, are experiencing is because there are low levels of COVID-19 here right now.

It's an indication public health measures are working and most people are abiding by them, said Strang.

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