Generally speaking, visitors to Japan do not require any special vaccinations
However, to be on the safe side, any routine immunizations should be kept up-to-date. Rubella, measles and even dengue fever (for which a vaccine is unavailable) have all made appearances in recent years.
Precautions should be taken to minimize exposure to mosquitoes during the rainy and summer months. Japanese encephalitis is a rare but sometimes fatal disease for which a vaccine is available. If you are only planning a short-term visit, or will be based in major cities such as Tokyo , Osaka , and Kyoto , you will likely not need this vaccine. However, if you have any doubts, consult with a doctor or medical professional before traveling.
What are routine immunizations?
The United States Centers for Disease Control and Prevention advises that visitors to Japan should have all their routine immunizations up to date. Such immunizations include:
Measles-mumps-rubella (MMR) vaccine Diphtheria-tetanus-pertussis vaccine (DTaP) vaccine Varicella (chickenpox) vaccine Polio vaccine
Some travelers should also consider getting vaccinations or booster shots dependent on their activities in Japan:
Hepatitis A (potential food and water contamination)
Hepatitis B (if you get a tattoo, have a sexual relationship with a new partner or undergo any medical procedures)
Rabies shots (if you plan to go caving or are planning outdoor adventure activities where bats are present)
Japanese Encephalitis (see below)
What is Japanese Encephalitis?
Japanese encephalitis is a mosquito-borne viral disease prevalent in Western Japan with peak transmission occurring during the early summer and fall seasons. Because the virus is spread via mosquitoes feeding on infected animals, birds and mammals, those most at risk are people visiting or working in and around rice fields, irrigation systems and in similar rural areas.
Symptoms may include fever, severe headache, diarrhea, vomiting and general lethargy but not everybody will show symptoms. In rare cases, the disease can be fatal. The best prevention against Japanese encephalitis is vaccination and insect bite prevention. Vaccinations need to be timed appropriately before traveling. For further information, consult your medical practitioner.
Have there been any outbreaks in Japan?
Japan has occasional outbreaks of infectious diseases. In recent times these have mostly included rubella and measles, while a now contained incident of dengue fever was traced to mosquitoes found in Tokyo's Yoyogi Park in 2014.
Visitors to Japan are advised to take precautions and keep routine vaccinations up-to-date to prevent any unnecessary transmission of these diseases. Pregnant women planning to visit Japan who have not been vaccinated against rubella should consult with their medical practitioner before traveling.
What about cold and flu season in Japan?
Japan's flu season runs through the winter months (December-March). Japan's urban centers are densely populated, and the influenza virus is known to spread rapidly. A flu epidemic hit the country in 2018 with over 2.8 million people affected. The CDC recommends visitors to Japan get an annual flu shot, especially if visiting during winter months, to reduce any severity of the illness if contracted.
What is Norovirus?
Norovirus, otherwise known as "noro" or stomach flu, is another transmissible disease common during winter. Symptoms include vomiting, diarrhea, and in severe cases, dehydration. Frequent handwashing is the best way to prevent the transmission of norovirus.