"The right to swing my fist ends where the other man's nose begins," wrote Oliver Wendell Holmes, Jr. Your liberty is constrained by the equal liberty of others to be left unharmed.

Holmes' principle applies when it comes to health care workers who endanger patients by refusing to get vaccinated against influenza. Many Americans acquire influenza infections from health care workers every year. Such infections are especially dangerous for the newborn, the elderly, and the immuno-compromised. Influenza vaccination rates among health care workers in the U.S. hovers around 50 percent.

University of Pennsylvania bioethicist Arthur Caplan argues in The Lancet that influenza vaccination should be made a mandatory condition of employment for all health care workers. He writes:

First, every code of ethics adopted by physicians, nurses, nurses aides, social workers, pharmacists, and other health-care professionals states very clearly, succinctly, and loftily that the interests of patients must come ahead of anyone else's… Second, all health-care workers are obligated to honour the core medical ethics requirement of "First Do No Harm"… Lastly, health-care workers have a special duty towards the vulnerable who cannot protect themselves… The case from professional ethics for influenza vaccination mandates is as strong a case as can be built in terms of duties and obligations. However, there is yet still another powerful moral reason to mandate vaccination for all professionals working in health care. By not vaccinating themselves, health-care workers feed vaccine fears, reinforce anti-vaccine sentiments, and set a dismally poor example for the public. Invoking personal choice in the face of obvious patient need for protection and ignoring the overwhelming safety of vaccination simply feeds public distrust of vaccination. At a time when epidemics of measles, whooping cough, and mumps are sweeping through many nations as a result of parental decisions not to vaccinate their children, is it not the duty of every health-care worker to provide a role model of what the right course of action is to take with respect to vaccination?

I think that Caplan makes a strong moral case for a vaccination mandate. In any case, I protect myself against careless health care workers by getting a flu vaccination every fall.