Nothing is 100 percent sure in science, but like fastening your seat belt, doctors play the odds to keep their patients and the public as safe as possible. Most decisions are obvious. For example, the chance of getting lung cancer is 25 percent for smokers but 1 percent for non-smokers, so not smoking is the safer choice.
Vaccines also have favorable odds. For example, vaccines for the measles and polio viruses are 97 percent and 99 percent effective respectively. Polio, once a feared childhood disease, crossed the United States each summer causing death or paralysis to 15,000 children annually. Like Covid-19, avoidance was the only prevention so places like public swimming pools were often off-limits (parental choice) or closed (town choice) to prevent community infection. Fortunately, virologist Jonas Salk developed a vaccine in the 1950’s which ended this terrible disease. Older readers may recall being part of the clinical trials for this vaccine in grade school.
Herd immunity may be achieved by either vaccination or infection. Viruses reproduce by hijacking the genetic machinery of a living host, but if enough people are vaccinated (95 percent for measles), the virus has trouble finding an unprotected host “in the herd” and fades away. Herd immunity may also occur naturally if enough people are infected and develop antibodies. For Covid-19, epidemiologists estimate that 70 percent of the U.S. population would need to be infected which would mean millions of deaths and massive medical, social, and economic problems. In short, immunity by vaccination is far safer, but until a vaccine is found the best way to slow the virus is basic prevention by avoiding crowds, social distancing, mask wearing and washing hands.
Public health raises questions of social responsibility vs individual choice such as, “Does one have a right to do whatever they want, even when it harms others such as smoking in public or texting while driving?” Ethics teaches that “with freedom comes responsibility” and that an easy way to decide responsible behavior is to ask, “If EVERYONE behaves my way, will the result be better or worse?” For example, if everyone texts while driving accidents will soar, so texting is not the responsible choice. Likewise, if no one vaccinates their children measles and polio will return, so vaccination is the responsible choice. Or for Covid-19, if no one wears masks the virus will spread and more will die, so mask wearing is the responsible choice. Ethics does respect individual rights if only the individual is affected (e.g., one’s right to refuse chemo treatment), but for matters of public health where one’s actions also affect others, acting to help the community is the responsible choice.