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Traffic on Highway 401 in Toronto passes under a COVID-19 sign on April 6, 2020.Frank Gunn/The Canadian Press

Once in a while, a story comes along that’s guaranteed to antagonize everyone. The most recent addition is a study conducted by scientists at the Sunnybrook Research Institute in Toronto entitled “COVID Vaccine Hesitancy and Risk of a Traffic Crash.”

Sunnybrook’s scientists conclude that COVID-19 vaccine hesitancy is “associated with significant increased risks of a traffic crash.”

It’s a finding that is sure to outrage both the vaccine enthusiasts who consider the vaccine hesitant selfish, ignorant and dangerous, and the vaccine hesitant who are convinced everyone is out to get them.

According to the study, published in The American Journal of Medicine, the Sunnybrook scientists conducted “a population-based longitudinal cohort analysis of adults and determined COVID-19 vaccination status through linkages to individual electronic medical records.” They subsequently identified traffic crashes requiring emergency medical care over a one-month follow-up interval. The scientists wanted to learn whether individuals who “tend to resist public health recommendations might also neglect basic road safety guidelines.”

They studied a total of 11,270,763 drivers of whom 16 per cent had not received a COVID-19 vaccine. “The cohort accounted for 6,682 traffic crashes during follow-up. Unvaccinated individuals accounted for 1,682 traffic crashes (25 per cent), equal to a 72 per cent increased relative risk compared with those vaccinated.”

It’s at this point you might expect my opinion on vaccination. Before I proceed, let’s examine my scientific qualifications:

  • Failed Grade 12 Biology with a 42
  • No idea how batteries work

I will, therefore, pass on delivering a summary judgment on the scientific findings of epidemiologists, immunologists and virologists as they seek to determine the key ethical considerations for governments when considering a COVID-19 vaccination and associated mandates. That said, I’m fully vaccinated.

Instead, let’s sort through the study and see what we can take away that can be applied to make us safer drivers.

The study used pre-existing data to examine a huge swathe of drivers. Its authors admit, “A limitation of our study is that correlation does not mean causality because our data do not explore potential causes of vaccine hesitancy or risky driving.” In other words, if 76 per cent of drivers involved in traffic accidents had breakfast, that doesn’t mean that having breakfast causes traffic accidents.

What’s also missing is exposure data. Factors related to driving that could affect results. For instance, how much difference was there in the distance people drove, where they drove and what they drove. The absence of exposure data is not because of any fault of the researchers, who write a “limitation of our study is the lack of direct data on driving exposure in different groups.” The scientists argue this limitation did not have a significant impact on the results and note they found that increased risks were not lower in urban locations and not higher on weekends. “A 100 per cent increase in driving distance, however, is unlikely to explain the magnitude of traffic risks observed in this study.”

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Despite the absence of causal and exposure data, the authors make some striking claims. According to the study’s lead investigator Dr. Donald Redelmeier, “Our study demonstrated traffic risks were 50 to 70 per cent more frequent for adults who had not been vaccinated compared to those who had. This does not mean COVID-19 vaccination directly prevents traffic crashes. Instead, it suggests that adults who do not follow public health advice may also neglect the rules of the road.”

A foundation of the research appears to be the belief that human behaviour is the most significant cause of traffic crashes. This leaves out two important factors in any crash – the automobile and the road. Any traffic accident is a combination of the drivers, cars and roads they use.

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Rural drivers must drive farther distances than urban drivers. When they get in an accident, they are more likely to be on an isolated road or highway and farther from immediate medical assistance. Low-income drivers drive automobiles that may not have the latest safety features. These are two important factors that could lead to an increase of accidents that require trips to emergency. Given this, it’s interesting that the Sunnybrook study did not find that living in a rural location increased the risk of accident.

The Sunnybrook scientists argue that physicians should remind their patients about the importance of wearing a seat belt, obeying speed limits and never driving drunk. They also maintain that “the findings suggest that unvaccinated adults need to be careful indoors with other people and outside with surrounding traffic.”

That, I believe, is what Mark Twain used to call “a stretch.” True, if you are unvaccinated, you are more likely to transmit the virus, but you are not any more likely to bump into someone or trip over the furniture.

As for the if, why, when and how the vaccine hesitant are associated with significant increased risks of a traffic crash, I will leave that to the millions of armchair immunologists on social media to debate.

Instead, let’s note that the Sunnybrook scientists also found that whether vaccine hesitant or vaccinated to the max, traffic crashes disproportionately involve those who live in poverty. Unfortunately, there is currently no vaccine for that.

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