First, a reminder of a strong justification for requiring, for example, a flu vaccination policy. According to the Johns Hopkins medical organization, around 226,000 people are hospitalized annually with the flu and 16 percent — 36,000 of them — die from it. “These are preventable deaths,” says Johns Hopkins.

In justifying its own mandatory vaccination policy to its employees, Hopkins states that “overall, voluntary programs have not been effective at markedly increasing vaccination rates.”

Legal experts who have weighed in on this topic say that you can require employees — with certain exceptions — to be vaccinated. Health care systems, like Johns Hopkins, have an easy time justifying its mandatory vaccination policy since many employees encounter sick patients who are more vulnerable to infection than other people. In fact several states require that health care workers receive annual flu vaccinations.

Grounds for Rejection

However, employees everywhere have a right to refuse to be vaccinated on the basis of a disability under the Americans with Disabilities Act (ADA) and on religious grounds under the Civil Rights Act. It might be tough for an employee to explain how a disability would inhibit his or her ability to receive a vaccination, unless perhaps the disability could trigger an adverse medical reaction. The religious exemption is the obstacle you are more likely to face.

Such employee claims, however, do not necessarily enable them to ignore your policy without consequence. In 2012, for example, the EEOC published a letter which it sent to an employer seeking guidance on this topic. The letter stated, in part, that “If it would not pose an undue hardship, an employer may be required to excuse an individual from a mandatory vaccination policy as a requested religious accommodation under Title VII [of the Civil Rights Act] or disability accommodation under the ADA.”

Verification Standards

If an employee’s basis for seeking exemption from the policy is on religious grounds, you don’t need to agree to it before carrying out a little investigation. According to the EEOC letter, “The employer is permitted to obtain supporting information.” But that might be a bit more complicated than asking to speak to the employee’s minister, priest, imam or rabbi.

Section 12 of the EEOC’s compliance manual states the following: “Since idiosyncratic beliefs can be sincerely held and religious, even when third-party verification is needed, it does not have to come from a church official or member, but rather could be provided by others who are aware of the employee’s religious belief or practice.”

Employees are required to cooperate with your efforts to make “reasonable inquiries for such supporting information,” otherwise they might forfeit their entitlement to an accommodation, according to the EEOC.

But even when the employee is cooperative, and the evidence establishes that the employee does truly have a basis for seeking a religious exemption, you can still turn the employee down due to the “undue hardship” ADA exception to the law’s “reasonable accommodation” requirements.

Creative Thinking

But the EEOC in its letter encourages employers to think of possible alternatives to the vaccination for those employees with legitimate grounds for seeking an exemption from the policy. An example would be requiring such employees to wear a mask, “if not done for retaliatory or discriminatory reasons.”

For most employers, flu is the most logical condition to build a vaccination policy around. Measles, not so much. University of California epidemiologist Arthur Reingold says that about 96 percent of adults in the U.S. are already immune to measles. So unless your organization is a hospital or perhaps a school system, requiring proof of measles vaccination might not be worth the trouble.

But what if an employee with measles infects other employees? Would those employees have grounds to sue you for not providing a safe and healthful workplace, free of recognized hazards, as required by OSHA? The odds are slim, in part because it would be tough to prove that you were aware of the situation. Measles symptoms initially begin with runny noses, which would not arouse suspicion.

However, if you do become aware than an employee has a serious infectious disease such as measles, the best approach might simply be to require that person to take paid sick leave. That’s how Disneyland handled measles-infected employees in its own ranks last year.

It’s a different matter for employers that don’t offer paid sick leave. Employees may feel compelled to come to work no matter what their health condition because they can’t afford to forfeit the pay. However, employers that do not offer sick pay might be more worried about managing high employee turnover rates than about establishing a vaccination policy.