TAIPEI (Taiwan News) — Taiwan’s Centers for Disease Control on Tuesday reported a six-year high in measles cases, with 36 so far this year.

Of those, 24 were imported and 12 were locally transmitted. All imported cases were linked to travel from Vietnam, per CNA.

The CDC's expanded vaccine recommendation now covers individuals born in or after 1966, broadening the previous cutoff of 1981. The measles, mumps, and rubella vaccine is the most effective way to prevent measles, according to the Chung Shan Medical University Hospital.

The 12 local cases were associated with previously identified clusters, all of which have completed their monitoring periods without additional infections. Two new cases reported last week involved men in their 30s, residing in northern and central Taiwan.

Both had recently returned from Vietnam. The cases were classified as imported after the men developed symptoms four and nine days after arrival, respectively.

Measles is a highly contagious respiratory illness transmitted through airborne particles, respiratory droplets, or direct contact with nasal and throat secretions. The incubation period typically lasts 10 to 12 days with no symptoms, but the virus can be spread from four days before to four days after the onset of the characteristic rash.

The two most recent patients are under home isolation. Contact tracing identified 128 close contacts in the northern case, who will be monitored through June 4, and 165 contacts in the central case, monitored through June 6.

Under updated guidelines, adults born in or after 1966 who plan to travel to areas with ongoing measles outbreaks, or whose jobs involve frequent contact with foreign nationals, are advised to consult a physician about self-paid MMR vaccination, especially if they are unsure of their immunity status. Vaccination is recommended at least two weeks before international travel to allow time for immunity to develop.

Currently, two brands of self-paid MMR vaccines are available in Taiwan, with about 21,000 doses on the market. Another 10,000 doses are undergoing inspection and are expected to be released soon.

The CDC said vaccine supply remains stable. Individuals ages 20 to 59 planning travel to Vietnam are strongly encouraged to seek medical evaluation and consider MMR vaccination before departure.

Taiwan introduced routine MMR vaccination in 1981. Although the vaccine offers more than 95% protection for up to 20 years, immunity can wane over time, particularly among adults in their 20s to 40s who were vaccinated in childhood but have not received boosters.

A nationwide immunity survey conducted from 2019 to 2020 found that seropositivity among people born between 1961 and 1965 reached 97%. In contrast, immunity rates among younger populations declined significantly, ranging from 93% to 42%.

Common symptoms of measles include fever, cough, runny nose, conjunctivitis, and a red rash. Most people recover within 18 days with proper care.