Noise Separation from Signals: How to Investigate “Adverse Reactions” to COVID-19 Vaccine-National

During ~ Prolonged concerns Above the blood clot of AstraZeneca COVID-19 vaccine For recipients, pandemics see other potential buzzwords emerging: “harmful reactions.”

According to experts, some people experience “adverse events” after vaccination. But the challenge for scientists is to determine if the response is directly related to the vaccine or simply by chance.

This is an important difference, but experts say it can be misunderstood, and people simply jump to conclusions about unjustified vaccine safety.

“Sadly, some people have a heart attack and some have blood clots in this time frame. Choose any symptom — someone because we’re dealing with tens of millions of people. “You will have,” said Isaac Bogotti, an infectious disease specialist based in the Toronto General Hospital.

“It certainly justifies the investigation, but it doesn’t necessarily mean that it’s related to vaccines.”

Different countries have different mechanisms for determining adverse effects after vaccination.

In Canada, reports on the safety of the COVID-19 vaccine Published weekly on the official website.. They fall into categories, each encapsulating mild to severe potential reactions.

All non-serious events such as injection site pain and serious adverse events such as hospitalization are aggregated and reported. However, reports are also divided by link to vaccine or lack of vaccine.

“Just because it’s an adverse event doesn’t mean it’s directly related to the vaccine,” said Alison Kelvin, a virologist at Dalhousie University, in a previous interview with Global News. ..

“I was able to get the vaccine and was hit by a car five hours later. It will be recorded as an adverse event.”

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Kelly Grindrod, a pharmacy professor at the University of Waterloo, says it’s like breaking the real connection from chance, and there are several ways scientists can analyze it.

She said timing and proximity play a big role.

“Let’s say you were destined to have a heart attack tomorrow … If you were given a new drug or vaccine the day before, you need to consider whether it is related in terms of proximity and time,” she says. I did.

“But the question is that you were always supposed to have that heart attack. Who was trying to do it anyway, and by chance they were vaccinated, and who You need to understand if you weren’t destined to have a heart attack. “

The same analysis is occurring in AstraZeneca, she said, and the same is true for other reactions after vaccination.

At present, there is no evidence that the vaccine was the cause of thrombus reports in Europe.Pharmaceutical company Sunday said As of early March, of the more than 17 million people vaccinated against this drug, 15 had deep vein thrombosis and 22 had pulmonary embolism.The report has led many countries to choose Suspend the use of vaccineDespite regulatory authorities around the world, including Health Canada and the World Health Organization There is no sign that the shot is the cause of the reaction..

Another way for researchers to determine if an adverse event is related to a vaccine is to find out how common the same reaction is among the general public. The first UK to make widespread shots said that reports of blood clots among citizens were not greater than those that normally occur.

“We first look at what the country’s baseline rate is and try to answer if it happens more often in the vaccinated group,” Grindrod said.

“It’s the signal-to-noise ratio. These are a lot of noise signals. Scientists understand what noise is, get rid of it, and what’s still sitting there is really still a signal? Or we need to find out if it’s all noise. “

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Experts say that the number of reported adverse events in Canada after vaccination inevitably increases over time.

As more people are vaccinated, more incidents will occur, but they are rare, Bogocchi said.

As of March 5, 1,923 adverse events were reported after COVID-19 vaccination. This is 0.085 percent of all doses given that day. Of these, 1,709 were considered non-serious and 214 were considered serious.

The Canadian reporting system does not provide those details, so it is unclear exactly what those side effects were, but experts say it could be in the full range.

In the United Kingdom, for example, drug analysis documents layout responses reported by individual COVID-19 vaccine recipients. 63-page document Unique to AstraZeneca, There are reports of blood clots forming after vaccination, but there are also claims of dry lips, “diet failure” and “crying”.

“We will collect data on all reported side effects,” Bogok said.

But as a healthcare provider, “we broadcast with caution,” Grindrod said.

“To be on the safe side, I’ll fill out and submit an adverse event report form. It’s up to them at Health Canada’s level to see if they do a lot of the same thing. That’s what happened in Europe. “

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Special attention should be paid to “special interest” or “safety signal” adverse events as they are actually related to the vaccine. So far, no safety signal has been reported in Canada.

“It means that despite (many) reported adverse events, none are directly related to vaccine-related post-vaccination life-threatening adverse events,” Kelvin said earlier. Said to.

“Here in Canada, we have not received any kind of safety signal.”

The pandemic may have focused the laser on vaccine-related side effects, but experts emphasize that the system for reporting potential anomalous reactions is not new.

The· Canada’s Adverse Events Following Immunization Monitoring System (CAEFISS) continuously monitors the safety of all vaccines sold in Canada, not just COVID-19.

Reports of vaccine-related reactions by recipients, no matter how small, are picked up through local health providers and state public health authorities and eventually reach the CAEFISS database operated by the Public Health Agency of Canada.

This data is used to identify adverse events that may require further investigation. The same applies to medicines and other medicines. MedEffect Canada system.

“As we progress, we don’t make up for this,” Bogok said. “These have been around for decades, and COVID-19 is no exception.”

Ultimately, Grindrod says the system is working as expected.

“Most people don’t pay attention to this kind of health care,” she said.

“This is real-time science. It’s a normal process. It’s the difference between clinical trials and real life.”

— Use Canadian Press files

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