Christopher Labos: Risk Assessment of Vaccine Side Effects

People should be more afraid of the virus and its consequences because even those who survive can suffer from long-term disability.

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There are several reasons why people do not get vaccinated. The reason I hear more is the fear of side effects. Personally, I think that people should be more afraid of the virus and its consequences because even the people who eventually survive can suffer a long-term disability and are not the same after the experience. But the news reports of side effects are understandably terrifying, particularly when they involve heart damage or neurological complications.

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Many people have been concerned about side effects such as Guillain-Barré syndrome (GBS), a neurological condition that can occur in some people after vaccination. What we often forget is that GBS can also occur after bacterial or viral infections, and the risk of GBS after vaccination is lower than after infection. GBS occurs when something causes the immune system to damage the peripheral nerves and causes weakness that begins in the legs and works its way up the body as the disease progresses. Fortunately, it is a temporary problem that often resolves on its own and most people return to normal. In rare cases, people need to receive intravenous antibodies as treatment, but the prognosis is generally good.

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But reports of GBS cases after vaccination have scared some people out of getting vaccinated. Unfortunately, when people discuss the side effects of vaccines, they often don’t put the risks in the proper context. A recent study in the Journal of the American Medical Association measured the actual risk of GBS after vaccination and found it to be very low. They modeled a few different scenarios, but even their “worst case” scenarios found that the GBS rate was only about eight cases per 100,000 person-years. The authors also added an important and often overlooked caveat that at least some GBS cases must be due to other causes and part of the “history rate” for the condition. So if we would normally expect to see two GBS cases per 100,000 person-years, only about six cases per 100,000 person-years can be attributed to the vaccine.

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While this risk is very low, another point should provide added peace of mind. When GBS occurs, it usually occurs shortly after vaccination and is not something that develops in the future. More importantly, the risk of GBS was particularly related to the Johnson & Johnson vaccine and not to the Pfizer or Moderna vaccines, which are the ones that are mainly used at this time. As such, it shouldn’t be a concern or reason not to get vaccinated for most people.

Another common concern is the fear of Bell’s palsy, another neurological problem that can result in facial paralysis that is also often temporary and generally leaves no lasting damage. Concerns about Bell’s palsy arose when the first Studies of the Pfizer and Moderna vaccines found four and three cases of Bell’s palsy, respectively, in a combined group of about 35,000 people. These were probably serendipitous findings and the risk was outweighed by the obvious benefit of vaccination. Still, the possibility worried some. But subsequent research has not confirmed that there is any real link, and two studies from Israel and Hong Kong they have not shown any significant increase in risk. Interestingly, the Hong Kong study showed an increased risk with the CoronaVac vaccine (which is not used in Canada or the US) but not with the Pfizer vaccine.

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In short, no one who has not yet been vaccinated has much to worry about regarding these two conditions. The risk, if real, is extremely low and is largely associated with vaccines that are not widely used in Canada. Too often we talk about side effects without acknowledging how rare they are and people assume that the risks of one vaccine apply to all vaccines, which is not true. It is understandable that people are concerned about side effects, but in almost all cases that fear is not justified.

Christopher Labos is a doctor from Montreal.

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Reference-montrealgazette.com

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