There has been an update to this story. See the bottom of this post.
The United States has logged at least 1,200 measles cases so far in 2025.
Although the U.S. had declared the extremely contagious disease under control in 2000, an increasing political vogue for rejecting vaccine science has, as widely predicted, resulted in the highest number of cases of the disease in a quarter century.
In an ominous sign for Americans and the new bureaucratic hurdles they could soon face if they want to travel internationally, the country of Honduras, which regularly appears on mainstream Caribbean and Mexican cruise itineraries, has responded to rising infection rates by mandating a new vaccine requirement for visitors from 24 countries.
Nations subject to the new vaccine requirement include the United States and Canada, which has reported more than 2,700 cases this year, according to the World Health Organization.
The vaccine requirement in Honduras begins July 7, but details are still coming together.
How to prove measles immunity in Honduras
According to an alert posted by the U.S. Embassy in Honduras, visitors will be required to show proof of vaccination or proof of a negative measles test before being permitted to enter the country. That could mean receiving the jab right then and there at the border entry point.
"According to the Secretary of State at the Ministry of Foreign Affairs and International Cooperation, Honduran authorities are requiring documentation to show proof of a measles vaccine for travelers coming from various countries, including the United States, for any travel over land, by sea, or by air for all foreign travels to Honduras," the alert advises.
Obtaining proof of vaccination is more easily said than done for millions of people who received their vaccinations when they were small children in the 1960s or early 1970s.
If a traveler cannot locate their vaccination record, then they will be required to produce proof of a negative measles test taken 72 to 80 hours before arrival.
That's usually accomplished by detecting the presence of antibodies through what's called a measles titer test, also known as a measles, mumps, rubella (MMR) immunity test.
Blood-work businesses such as Labcorp charge $129 for MMR test documentation. The MinuteClinic at CVS charges $99–$139.
Theoretically, health documentation will be inspected before travelers are permitted to board flights to Honduras or before boarding a cruise ship scheduled to stop in Honduras. The island of Roatán, the most popular cruise port in Honduras, is visited by most of the major cruise lines.
For cruise passengers who cannot find proof of measles vaccination or supply a recent negative test, reports say the Honduran government may administer a measles vaccine dose on the spot. The cost, if there is one, has not been announced—so don't count on that option quite yet.
According to Harvard Health, receiving an additional dose of the MMR vaccine "is very safe and not harmful," even if you have already been vaccinated.
Click here to watch a video announcement, in Spanish, from the Honduran Migration department explaining the new requirement.
The government spokesperson in the video implies that these measures should only be in place up to 3 months while Honduras works to ensure all of its citizens are vaccinated, although that time frame could change.
Texas accounts for more than half the recorded outbreaks in the United States, but there have been cases reported in nearly three dozen states, ranging from Hawaii to Michigan.
In 95% of those cases, the patient's vaccination status has been recorded as "unvaccinated or unknown." Only about 5% of infections happened in people with vaccination records.
For updated instructions, keep an eye on the website of the U.S. Embassy in Honduras.
Update, July 4, 2025: According to a post on the Facebook page of the U.S. Embassy in Tegucigalpa and on the U.S. Embassy's website, the order has been reversed: "No requirement for proof of a measles and rubella vaccine for U.S. Citizen travelers arriving in Honduras." No explanation for the change was given.