Choosing the sidewalk

A few years ago in Center City Philadelphia, a man was walking on the sidewalk along South  Broad Street when an out-of-control taxi jumped the curb, struck and killed him.  

Maybe you remember this. If so, your response to the news was probably shock, sadness, and  empathy for his loved ones. However, I doubt very much that your reaction was “Wow, if that  guy had been walking in the middle of the street, he’d be alive today. I’m going to walk in the  street from now on.”  

When we choose every day to walk on the sidewalk instead of in the street, we are attempting  to estimate our risks and then engage in behavior that minimizes those risks. Overall we know  that we are far less likely to be struck on the sidewalk than on the street, even though on rare  occasions an errant car might prove us horribly wrong.  

We perform similar assessments many times per day, from decisions regarding seat belts to  decisions regarding medications for asymptomatic conditions like high blood pressure and high  cholesterol.  

It turns out that as human beings we are sometimes pretty poor at assessing our risks. We  overestimate some risks, like the chances of death from airline crashes or terrorism, even as we  underestimate other risks, like deaths caused by smoking or car accidents. 

Often it is our emotions that cause us to distort our risks. One of the best things we can do is  remove emotion from our risk assessment. So even though my emotional brain caused me to  flinch every time a taxi passed after that poor man’s death on South Broad Street, I was still  safer on the sidewalk.  

In medicine, every decision to treat begins with a non-emotional assessment of risks and  benefits. As a physician, one of the most valuable services I can offer a patient is a fair, unbiased  judgment of risks and benefits that allows the patient to make the final decision of how to  proceed.  

With vaccinations, we make similar judgments. Smallpox was a horrible viral disease that killed  up to 20 percent of the British population at the time William Jenner developed a vaccine  against it in the 1790s. The risk of disease remained high and vaccination continued in the US  until 1972, because until then the benefits of vaccination were judged to outweigh the risks.  (Smallpox was eradicated in North America in 1952, and worldwide by 1979; my brother was  born in 1967 and vaccinated against smallpox; I was born in 1968 and was not).  

Vaccines are recommended when the benefits of vaccination outweigh the risks. For diseases  like polio, the risk of disease in the US is very low (because of vaccination) but the vaccine is  extremely safe, so the benefits are judged to outweigh the risks, and vaccination is  recommended. For influenza, the vaccine has more risk (still extremely low) but the risk of  disease is high, so again the benefits outweigh the risks and vaccination is recommended.  Meanwhile, because smallpox vaccination no longer offers benefit, it is no longer offered. 

Vaccines also have a societal benefit - the building of herd immunity. When an individual gets  vaccinated, she is doing society as a whole some good by chipping away at a virus’ ability to  infect the population. But for our purposes here, let’s forget that societal benefit and  concentrate just on the individual.  

The mRNA vaccines were tested on 38,000 individuals and have been administered to over 120  million Americans. Their effectiveness is fantastic (95% reduction in symptomatic infection!),  far above the level of which many dared to dream. DNA vaccines like those produced by  AstraZeneca and Johnson and Johnson also offer tremendous efficacy. Other vaccine candidates,    including the Covaxin vaccine developed in India using the same technology as the polio  vaccine should be added to our toolkit soon. 

Not surprisingly, as vaccination has moved from thousands to millions, rare but real side effects  have been and will continue to be discovered.  

However, the chances of one of these rare but real side effects harming you is minuscule  compared to the chance of the virus harming you. COVID-19 has already killed more than 1 in  every 600 Americans, and it will leave hundreds of thousands of debilitated survivors in its  wake. It has destroyed many millions of other lives indirectly.  

Unless one has one of certain rare and specific allergic or immunological conditions, getting vaccinated against COVID-19 is far more likely to help you than to harm you. If you walk on the  sidewalk, you probably agree.

A few years ago in Center City Philadelphia, a man was walking on the sidewalk along South  Broad Street when an out-of-control taxi jumped the curb, struck and killed him.  

Maybe you remember this. If so, your response to the news was probably shock, sadness, and  empathy for his loved ones. However, I doubt very much that your reaction was “Wow, if that  guy had been walking in the middle of the street, he’d be alive today. I’m going to walk in the  street from now on.”  

When we choose every day to walk on the sidewalk instead of in the street, we are attempting  to estimate our risks and then engage in behavior that minimizes those risks. Overall we know  that we are far less likely to be struck on the sidewalk than on the street, even though on rare  occasions an errant car might prove us horribly wrong.  

We perform similar assessments many times per day, from decisions regarding seat belts to  decisions regarding medications for asymptomatic conditions like high blood pressure and high  cholesterol.  

It turns out that as human beings we are sometimes pretty poor at assessing our risks. We  overestimate some risks, like the chances of death from airline crashes or terrorism, even as we  underestimate other risks, like deaths caused by smoking or car accidents. 

Often it is our emotions that cause us to distort our risks. One of the best things we can do is  remove emotion from our risk assessment. So even though my emotional brain caused me to  flinch every time a taxi passed after that poor man’s death on South Broad Street, I was still  safer on the sidewalk.  

In medicine, every decision to treat begins with a non-emotional assessment of risks and  benefits. As a physician, one of the most valuable services I can offer a patient is a fair, unbiased  judgment of risks and benefits that allows the patient to make the final decision of how to  proceed.  

With vaccinations, we make similar judgments. Smallpox was a horrible viral disease that killed  up to 20 percent of the British population at the time William Jenner developed a vaccine  against it in the 1790s. The risk of disease remained high and vaccination continued in the US  until 1972, because until then the benefits of vaccination were judged to outweigh the risks.  (Smallpox was eradicated in North America in 1952, and worldwide by 1979; my brother was  born in 1967 and vaccinated against smallpox; I was born in 1968 and was not).  

Vaccines are recommended when the benefits of vaccination outweigh the risks. For diseases  like polio, the risk of disease in the US is very low (because of vaccination) but the vaccine is  extremely safe, so the benefits are judged to outweigh the risks, and vaccination is  recommended. For influenza, the vaccine has more risk (still extremely low) but the risk of  disease is high, so again the benefits outweigh the risks and vaccination is recommended.  Meanwhile, because smallpox vaccination no longer offers benefit, it is no longer offered. 

Vaccines also have a societal benefit - the building of herd immunity. When an individual gets  vaccinated, she is doing society as a whole some good by chipping away at a virus’ ability to  infect the population. But for our purposes here, let’s forget that societal benefit and  concentrate just on the individual.  

The mRNA vaccines were tested on 38,000 individuals and have been administered to over 120  million Americans. Their effectiveness is fantastic (95% reduction in symptomatic infection!),  far above the level of which many dared to dream. DNA vaccines like those produced by  AstraZeneca and Johnson and Johnson also offer tremendous efficacy. Other vaccine candidates,    including the Covaxin vaccine developed in India using the same technology as the polio  vaccine should be added to our toolkit soon. 

Not surprisingly, as vaccination has moved from thousands to millions, rare but real side effects  have been and will continue to be discovered.  

However, the chances of one of these rare but real side effects harming you is minuscule  compared to the chance of the virus harming you. COVID-19 has already killed more than 1 in  every 600 Americans, and it will leave hundreds of thousands of debilitated survivors in its  wake. It has destroyed many millions of other lives indirectly.  

Unless one has one of certain rare and specific allergic or immunological conditions, getting vaccinated against COVID-19 is far more likely to help you than to harm you. If you walk on the  sidewalk, you probably agree.