<unk> , also known as chickenpox vaccine, is a vaccine that protects against chickenpox. One dose of vaccine prevents 95% of moderate disease and 100% of severe disease. Two doses of vaccine are more effective than one. If given to those who are not immune within five days of exposure to chickenpox it prevents most cases of disease. Vaccinating a large portion of the population also protects those who are not vaccinated. It is given by injection just under the skin. Another vaccine, known as zoster vaccine, is used to prevent diseases caused by the same virus - the<unk>  zoster virus. The World Health Organization (WHO) recommends routine vaccination only if a country can keep more than 80% of people vaccinated. If only 20% to 80% of people are vaccinated it is possible that more people will get the disease at an older age and outcomes overall may worsen. Either one or two doses of the vaccine is recommended. In the United States two doses are recommended starting at twelve to fifteen months of age. , twenty-three countries recommend all non-medically exempt children receive the vaccine, nine recommend it only for high risk groups, three additional countries recommend use in only parts of the country, while other countries make no recommendation. Not all countries provide the vaccine due to its cost. In the United Kingdom, Varilrix, a live viral vaccine is approved from the age of 12 months. Minor side effects may include pain at the site of injection, fever, and rash. Severe side effects are rare and occur mostly in those with poor immune function. Its use in people with HIV/AIDS should be done with care. It is not recommended during pregnancy; however, the few times it has been given during pregnancy no problems resulted. The vaccine is available either by itself or along with the MMR vaccine, in a version known as the MMRV vaccine. It is made from weakened virus. A live attenuated<unk> , the Oka strain, was developed by Michiaki Takahashi and his colleagues in Japan in the early 1970s. American vaccinologist Maurice Hilleman's team developed a chickenpox vaccine in the United States in 1981, based on the "Oka strain" of the<unk>  virus. The chickenpox vaccine first became commercially available in 1984. It is on the WHO Model List of Essential Medicines.
Varicella vaccine
Measles vaccine
Hantavirus vaccine
Typhus vaccine
Polio vaccine
Typhoid vaccine
Ebola vaccine
Mumps vaccine