Measles vaccine

Measles vaccine is a vaccine that prevents measles. Nearly all of those who do not develop immunity after a single dose develop it after a second dose. When rates of vaccination within a population are greater than 92% outbreaks of measles typically no longer occur; however, they may occur again if rates of vaccination decrease. The vaccine's effectiveness lasts many years. It is unclear if it becomes less effective over time. The vaccine may also protect against measles if given within a couple of days after exposure to measles. Measles vaccine is a vaccine that prevents measles. Nearly all of those who do not develop immunity after a single dose develop it after a second dose. When rates of vaccination within a population are greater than 92% outbreaks of measles typically no longer occur; however, they may occur again if rates of vaccination decrease. The vaccine's effectiveness lasts many years. It is unclear if it becomes less effective over time. The vaccine may also protect against measles if given within a couple of days after exposure to measles. The vaccine is generally safe, even for those with HIV infections. Side effects are usually mild and short lived. These may include pain at the site of injection or mild fever. Anaphylaxis has been documented in about 3.5–10 cases per million doses. Rates of Guillain–Barré syndrome, autism and inflammatory bowel disease do not appear to be increased by measles vaccination. The vaccine is available both by itself and in combinations such as the MMR vaccine (a combination with the rubella vaccine and mumps vaccine) or the MMRV vaccine (a combination of MMR with the chickenpox vaccine). The measles vaccine is equally effective for preventing measles in all formulations, but side effects vary depending with the combination. The World Health Organization recommends measles vaccine be given at nine months of age in areas of the world where the disease is common, or at twelve months where the disease is not common. Measles vaccine is based on a live but weakened strain of measles. It comes as a dried powder which is mixed with a specific liquid before being injected either just under the skin or into a muscle. Verification that the vaccine was effective can be determined by blood tests. About 85% of children globally have received this vaccine as of 2013. In 2015, at least 160 countries provided two doses in their routine immunization. The measles vaccine was first introduced in 1963. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. The wholesale cost in the developing world is about 0.70 USD per dose as of 2014. As outbreaks easily occur in under-vaccinated populations, the disease is seen as a test of sufficient vaccination within a population. Before the widespread use of the vaccine, measles was so common that infection was considered 'as inevitable as death and taxes.' In the United States, reported cases of measles fell from hundreds of thousands to tens of thousands per year following introduction of the vaccine in 1963 (see chart at right). Increasing uptake of the vaccine following outbreaks in 1971 and 1977 brought this down to thousands of cases per year in the 1980s. An outbreak of almost 30,000 cases in 1990 led to a renewed push for vaccination and the addition of a second vaccine to the recommended schedule. No more than 220 cases were reported in any year from 1997 to 2013, and the disease was believed no longer endemic in the United States. In 2014, 667 cases were reported. The benefit of measles vaccination in preventing illness, disability, and death have been well documented. Within the first 20 years of being licensed in the U.S., measles vaccination prevented an estimated 52 million cases of the disease, 17,400 cases of mental retardation, and 5,200 deaths. During 1999–2004, a strategy led by the World Health Organization and UNICEF led to improvements in measles vaccination coverage that averted an estimated 1.4 million measles deaths worldwide. The vaccine for measles has led to the near-complete elimination of the disease in the United States and other developed countries. While the vaccine is made with a live virus which can cause side effects, these are far fewer and less serious than the sickness and death caused by measles itself, side effects ranging from rashes to, rarely, convulsions, occur in a small percentage of recipients. Measles is common worldwide. Although it was declared eliminated from the U.S. in 2000, high rates of vaccination and excellent communication with those who refuse vaccination are needed to prevent outbreaks and sustain the elimination of measles in the U.S. Of the 66 cases of measles reported in the U.S. in 2005, slightly over half were attributable to one unvaccinated individual who acquired measles during a visit to Romania. This individual returned to a community with many unvaccinated children. The resulting outbreak infected 34 people, mostly children and virtually all unvaccinated; 9% were hospitalized, and the cost of containing the outbreak was estimated at $167,685. A major epidemic was averted due to high rates of vaccination in the surrounding communities. The vaccine has non specific effects such as preventing respiratory infections, that may be greater than those of measles prevention alone. These benefits are greater when the vaccine is given before one year of age. A high titre vaccine resulted in worse outcomes in girls and thus is no longer recommended by the World Health Organization. The World Health Organization recommends two doses of vaccine for all children. In countries with high risk of disease the first dose should be given around nine months of age. Otherwise it can be given at twelve months of age. The second dose should be given at least one month after the first dose. This is often done at age 15 to 18 months. After one dose at the age of nine months 85% are immune, while a dose at twelve months results in 95% immunity.