Herd immunity: how it works and why it is a high goal of COVID-19-nationwide

Herd immunity may not be a viable goal of Canada’s vaccination efforts COVID-19 (New Coronavirus Infection), But it also doesn’t have to return to a more normal life, experts say.

This has to do with some unique features of the virus, as well as mathematics.

Herd immunity is the protection of a sufficient number of people from illness by being vaccinated or by catching, recovering, and developing antibodies.

If a particular population has herd immunity, even if the disease is reintroduced, it will not lead to an outbreak, as most people are protected.

He is a pediatric infectious disease specialist at the Eastern Ontario Children’s Hospital and immunizes Canada.

“It’s like immunological teamwork,” she said.

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She said that all diseases have different thresholds of herd immunity, depending on the degree of infectivity and how effective the vaccine is in preventing it.

A good example is measles. It is incredibly infectious — each infected person can pass measles to 12-18 people — but the vaccine is also 99 percent effective in preventing infection. Still, according to the World Health Organization (WHO), 95% of the population needs to be vaccinated to prevent outbreaks.

And if a small number of people are not completely vaccinated, they may have a relapse, as follows: Happened in 2014 BC.. Measles is still by our side and we need to keep track of vaccinations to keep them at a manageable level.

“Once you have established herd immunity, you can’t wash your hands and say,” Fine, no more vaccinations. ” It’s easy to see when a small pocket is created for people who are immune to measles. And therefore, it is susceptible to measles and spreads very quickly, “says Pham-Huy.

And with COVID-19, the calculations are even more complicated for all unknowns.

In a recent analysis, researchers at Simon Fraser University sought to estimate what it would take to be able to fully resume without an increase in cases. They concluded that it was unlikely to be our current vaccination program.

“We should aim for 95% of adults and 80% of children aged 12-19. If we can achieve that, that’s our best chance,” said a professor of mathematics at Simon Fraser University. Co-author Paul Tapper said.

But it’s hard to hit those numbers.

“It seems expensive. I don’t know if it’s realistic,” Tupper said.

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First, vaccines are not completely effective in preventing infection. In his paper, Tupper estimated that the Pfizer vaccine provides much stronger protection against severe illness, but is about 80% effective in preventing infection after two doses.

Approximately 3.3% of Canadians have confirmed cases of COVID-19, according to data from the Public Health Agency of Canada. Pham-Huy said he does not know exactly how strong and long-lasting this innate immunity is. Even with the vaccine, the vaccine is so new that it has not been studied for multiple years yet.

Moreover, not everyone is vaccinated. Some people dislike vaccines, and although they are eligible, they may not want injections. Then there are groups like children under the age of 12 who do not yet have an approved vaccine. This means that not only do you get sick yourself, but you also have pockets of people who can infect others with the virus.

And there are variants issues, some of which may one day evade our vaccine.

For COVID-19, the initial estimate of the herd immunity threshold was 60-70%, said Ashley Chuite, an epidemiologist at the University of Toronto’s Dallalana School of Public Health. This has since been modified to nearly 80 percent immunity, as a more virulent strain of the virus has taken over, she said.

“And when talking about 80% immunity, it’s a bit different from the 80% vaccinated, because the vaccine isn’t 100% effective in reducing infections,” she said.

The new strain and its effects are the “greatest unknown and greatest hurdle” to reach herd immunity, Tuite says. Therefore, relying solely on vaccination may not reach it.

“I think we can still vaccinate a way out of this. It just thinks it’s not always realistic for us to reach herd immunity, but I don’t think it’s a bad thing.” Tuite said.

“There are many infectious diseases for which we do not have herd immunity. And we are okay. We will deal with it.”

COVID-19 could lead to another illness that exists in our background, she said, adding that if vaccination can control hospitalization and serious illness, it can return to normal. I did.

Even with herd immunity, it still takes time for the epidemic to subside, and it can occur occasionally, according to Tuite.

“It’s hard to predict what will happen in the future, but at this point I don’t think elimination or eradication is where we’re heading,” she said.

“We are heading to use vaccination to protect as many people as possible so that when a case is referred, a more manageable outbreak occurs.”

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