TAIPEI (Taiwan News) — Taiwan’s Centers for Disease Control has announced a measles cluster involving four new cases directly associated with a man in his 40s who visited relatives in Vietnam.

Measles was transmitted to a family caregiver, an emergency room nurse, a cleaner, and a passenger from the same flight. The new cases all experienced symptoms appearing between Dec. 11-13, per UDN.

Health authorities have also identified 152 contacts coming into contact with individuals in this measles cluster and each individial will be monitored until Jan. 5. CDC Spokesperson Tseng Shu-hui (曾淑慧) said the list of contacts includes 28 airline passengers seated near the initial measles case.

Tseng said the CDC and the local health bureau visited the hospital at the center of the measles cluster infection on Tuesday (Dec. 17). It recommended the hospital strengthen infection control measures, including measles, mumps, and rubella vaccinations for all hospital employees who do not have a record of measles vaccination or show related antibodies in a blood test.

The MMR vaccine is generally administered to children at the age of 12 months and then again with a booster at 10 years of age. Thus, many people in Taiwan have measles antibodies, though approximately 10 measles cases occur each year.

Tseng said measles is airborne in its transmission and is contagious for four days before and after a rash appears. The transmissibility of the illness is quite high, with one person potentially infecting between 18-20 people.