Measles

A.1 It was common to be infected with measles and naturally acquire immunity during childhood. The increased measles vaccination coverage, however, decreased the number of measles cases. Some people in their 10s and 20s have not received measles vaccination. In addition, a single dose of vaccination does not always confer sufficient immunity. It is known that a small percent of people do not acquire sufficient immunity by receiving measles vaccination just once. It is believed that such people were one of the causes of the epidemic.
Furthermore, the increased coverage of measles vaccination decreased the number of measles patients, which decreased opportunities for exposure to measles virus. As a result, people in their 10s and 20s at the time who had received measles vaccination only once in their childhood could not reinforce their immunity, which gradually weakened over time. This is also believed to be another cause of the epidemic.

A.2　A.2 Getting infected with measles during pregnancy has potential to cause miscarriage or premature birth. Women who have not received a measles-containing vaccine or contracted the disease should actively consider receiving the vaccine before pregnancy. However, women known to be pregnant should not receive measles vaccine in general. You need to stay indoors and avoid crowds during measles epidemic. If your housemate is likely to contract measles (e.g. healthcare professionals and educators who have not completed two doses of measles vaccination and are more likely to be exposed to measles virus) during measles epidemic, consult your physician about vaccination and other measures.

A.3 If you develop measles in countries/regions where there are either none or only rare measles cases, not only you but also your traveling companion will be strictly restricted in travelling for the purpose of preventing spread of the infection.

A.4　A.4 Only from a few to double digit measles cases are reported annually in Americas (imported cases and those related to them) and many Middle Eastern and European countries. On March 2015, the World Health Organization (WHO) Western Pacific Regional Office verified that Japan had achieved measles elimination. On the other hand, still a large number of patients are reported in Asian and African countries. There are many reported cases especially from China, India, Mongolia, Pakistan, Nigeria and other countries shown in brown color in the map below.
Most developed countries including Japan have adopted two doses of measles-containing vaccination (mostly MMR (measles, mumps and rubella) vaccine) against measles. Accordingly there are an increasing number of countries achieving measles elimination. On September 27, 2016, WHO declared that the Region of the Americas had eliminated measles.
However, there are still many measles cases (diagnosed through examination) in many regions as shown by the figure below. Therefore, we recommend people who have not contracted (been diagnosed with) measles to check their measles vaccination history before traveling overseas, and, if they have not received two doses of vaccination or past vaccination history is unknown or uncertain, to receive measles vaccination.

• Quarantine Information Office, Ministry of Health, Labour and Welfare, the Government of Japan (FORTH) measles/rubella epidemic situation (as of April 2016)
• Fact sheet (Measles) Original text（WHO）(in English)
• Ministry of Foreign Affairs / Overseas Safety HP
• Tabiregi (Ministry of Foreign Affairs)
• WHO Immunization, Vaccines, Biologicals　measles　(In English）

Figure: Number of reported measles cases by country (from September 2017 to February 2018)

• http://www.who.int/immunization/monitoring_surveillance/burden/vpd/surveillance_type/active/measles_monthlydata/en/

A.5　A.5 If it is definite that you have had measles in the past (measles infection was confirmed through examination), you are immune to measles and do not need to receive vaccination. If it is uncertain whether you have had measles, consult your physician. Vaccination to people with a history of measles will not increase adverse effects.
Even if you have had either measles or rubella, you can receive measles-rubella vaccine as routine immunization if you are eligible age for the routine immunization.

A.6　A.6 People in the target age of routine immunization (infants in their second year of life and children in the year prior to admission to elementary school) are subject to active recommendation. Others who have never contracted measles or been vaccinated are recommended to consult their primary care physician.
People who were born on April 2, 1990 or later receive two doses of measles-containing vaccine as routine immunization, but most people who were born before the date have received only one dose. Especially healthcare, school, nursing/welfare personnel and other people at increased risk of measles or who will have a large impact on people around them by contracting measles, and people who plan to travel overseas are recommended to consult their physician regarding the second dose of vaccination.

A.7　MR vaccine is expected to have measles prevention effect similar to a measles monovalent vaccine.
There is no health problem in receiving MR vaccine instead of measles monovalent vaccine. It has an advantage of preventing also rubella.
However, because MR vaccine is live attenuated vaccine, women known to be pregnant should not receive it. Even if you are currently not pregnant, pregnancy should be avoided for about two months following MR vaccine to avoid influence on the fetus as much as possible.
Women known to be pregnant should not receive monovalent measles vaccine or rubella vaccine either. It is also necessary to avoid pregnancy for about two months following vaccination and take similar precautions.