Measles vaccine
Measles vaccine protects against becoming infected with measles.[1] Nearly all of those who do not develop immunity after a single dose develop it after a second dose.[1] When the rate of vaccination within a population is greater than 92%, outbreaks of measles typically no longer occur; however, they may occur again if the rate of vaccination decreases.[1] The vaccine's effectiveness lasts many years.[1] It is unclear if it becomes less effective over time.[1] The vaccine may also protect against measles if given within a couple of days after exposure to measles.[2][1][3][4]
Vaccine description
Measles virus
- none
The vaccine is generally safe, even for those infected by HIV.[1][5] Most children do not experience any side effects;[6] those that do occur are usually mild, such as fever, rash, pain at the site of injection, and joint stiffness; and are short-lived.[1][6] Anaphylaxis has been documented in about 3.5–10 cases per million doses.[1] Rates of Guillain–Barré syndrome, autism and inflammatory bowel disease do not appear to be increased by measles vaccination.[1][7]
The vaccine is available both by itself and in combinations such as the MMR vaccine (a combination with the rubella vaccine and mumps vaccine)[1] or the MMRV vaccine (a combination of MMR with the chickenpox vaccine).[8][9][10] The measles vaccine is equally effective for preventing measles in all formulations, but side effects vary for different combinations.[1][11] The World Health Organization (WHO) 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.[12][1] Measles vaccine is based on a live but weakened strain of measles.[1] 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.[1] Verification that the vaccine was effective can be determined by blood tests.[1]
The measles vaccine was first introduced in 1963.[13] In that year, the Edmonston-B strain of measles virus was turned into a vaccine by John Enders and colleagues and licensed in the United States.[14][15] In 1968, an improved and even weaker measles vaccine was developed by Maurice Hilleman and colleagues, and began to be distributed, becoming the only measles vaccine used in the United States since 1968.[16][14][15] About 86% of children globally had received at least one dose of the vaccine as of 2018.[17] In 2021, at least 183 countries provided two doses in their routine immunization schedule.[18] It is on the World Health Organization's List of Essential Medicines.[19] As outbreaks easily occur in under-vaccinated populations, non-prevalence of disease is seen as a test of sufficient vaccination within a population.[20][21]
Society and culture[edit]
Most health insurance plans in the United States cover the cost of vaccines, and Vaccines for Children Program may be able to help those who do not have coverage.[63] State law requires vaccinations for school children, but offer exemptions for medical reasons and sometimes for religious or philosophical reasons.[64] All fifty states require 2 doses of the MMR vaccine at the appropriate age.[65] A different vaccine distribution within a single territory by age or social class may define different general perceptions of vaccination efficacy. [66]