Cedars-Sinai Medical Center is cautioning travelers to get vaccinated before heading on vacation.

Although polio has largely receded from public health concerns in the U.S., where it was eliminated more than four decades ago, strains of the virus that causes the disease still circulate in parts of Europe, Asia and Africa. Measles is also a concern in the U.S., where outbreaks have recently been reported in Pennsylvania, Virginia and Utah, pushing the total number of cases in the U.S. during 2026 to more than 2,220 – a number already higher than last year.

“More than anything, it’s a good reminder that staying up to date on vaccinations is critical to staying safe and healthy while traveling,” said Dr. Michael Ben-Aderet, associate director of Hospital Epidemiology at Cedars-Sinai.

Polio is caused by a highly contagious virus that has essentially been eliminated from most of the world through vaccination. Wild strains still persist in a handful of countries, including Afghanistan and Pakistan, which means the vast majority of international travelers are at relatively low risk, particularly if they’ve been vaccinated. In recent years, roughly 30 countries in Africa, Europe and Asia, including the U.K. and Germany, have shown signs of the virus circulating. However, those signs are not necessarily tied to outbreaks. For example, public health officials in the U.K. have detected the virus in wastewater tests, which likely points to some degree of asymptomatic polio.

The poliovirus typically spreads when an infected person doesn’t wash their hands and contaminates water, food or other surfaces. It usually causes a mild illness from which most people quickly recover. What makes polio historically concerning is that a small percentage of infections can progress to paralysis, typically affecting the legs and feet, when the virus invades the nervous system. Vaccination is so important has essentially eliminated the fear or polio-related paralysis in populations where immunization rates are high.

Almost everyone in the U.S. received the polio vaccination series as a child. For vaccinated travelers, the risk is minimal. For older adults concerned that immunity may have waned over the years, a booster is available. The polio vaccine has minimal side effects, so there is little harm in getting the vaccine. Those who receive the polio vaccine do not receive the full benefit of immunity until four weeks after vaccination.

Measles is a more immediate risk to summer travelers, especially in crowded or enclosed spaces. It’s far more contagious, spreading through airborne particles from an infected person’s cough or sneeze, and can stay in the air for up to two hours.

Recent clusters have emerged in parts of California, Texas and Oklahoma, and the largest outbreaks have been reported in India, Bangladesh, Yemen, Mexico and Pakistan.

Most fully vaccinated individuals are well protected from measles for life. Adults who are uncertain whether they received the two doses of the MMR vaccine, which protects against measles, mumps and rubella, should consider getting at least one dose. Children are recommended to receive two doses: one at 12-15 months and another at 4-6 years old. Babies 6-11 months old should get one dose before they travel, and two more doses after their first birthday.

For information, visit cedars-sinai.org.