Measles vaccination

Prevention of measles in emergency situations has two major components: routine vaccination and measles outbreak response. The disease can be prevented by the administration of measles vaccine. Some 95% of individuals vaccinated when over 9 months old gain lifelong immunity. Mass vaccination is a priority in emergency situations where people are displaced, there is disruption of normal services, there are crowded or insanitary conditions and/or where there is widespread malnutrition, regardless of whether a single case of measles has been reported or not. A measles vaccination campaign should begin as soon as the necessary human resources, vaccine, cold chain equipment and other supplies are available. Measles vaccination should not be delayed until other vaccines become available or until cases of measles have been reported (if cases are reported the campaign should begin within 72 hours of the first report). Vaccination is also a priority in refugee populations from countries with high vaccination rates, as studies have shown that large outbreaks of measles can occur even if vaccine coverage exceeds 80%. It is important to remember that measles is a highly contagious disease requiring 96% coverage for herd immunity to be established. The presence of several cases of measles in an emergency setting does not preclude a measles vaccination campaign. Even among individuals who have already been exposed and are incubating the natural virus, measles vaccine, if given within 3 days of infection, may provide protection or modify the clinical severity of the illness. If cases of measles occur, isolation is not indicated and children with measles participating in selective feeding programmes should not be withdrawn.

The emergency-affected population must be vaccinated during the first days of the emergency and all new arrivals should be vaccinated. The target age group depends on the vaccine coverage in the country of origin of the affected population. The optimal age group to vaccinate for measles is 6 months through 14 years of age if possible, with a minimum acceptable age range of 6 months through 4 years of age. The target age group for vaccination must be chosen based on vaccine availability, funding, human resources and local measles epidemiology. A measles control plan should be developed and implemented as rapidly as possible while ensuring high quality in coverage, cold chain/ logistics, and vaccination safety. Children aged between 6 and 9 months should be revaccinated as soon as they reach 9 months of age.

• Measles vaccination should be accompanied by vitamin A distribution in children aged 6 months to 5 years to decrease mortality and prevent complications.

A pre-vaccination count of the target population should be conducted, but this should not delay the start of the vaccination programme. In long-term refugee health programmes, vaccination should be targeted at all children aged between 9 months and 5 years.

If there is insufficient vaccine available to immunize the entire target population, the following high-risk groups should be targeted (in order of priority):

• undernourished or sick children aged 6 months to 12 years who are enrolled in feeding centres or inpatient wards,

• all other children aged 6-23 months,

• all other children aged 24-59 months.

Older children and adults may need to be immunized if surveillance data show that these age groups are being affected during an outbreak. Table 2.31 summarizes the key points concerning measles vaccination and vaccines.

Malnutrition is not a contraindication for measles vaccination; on the contrary, it should be considered a strong indication for vaccination. Similarly, fever, respiratory tract infection and diarrhoea are not contraindications for measles vaccination. Children with HIV infection or clinical AIDS should receive measles vaccine because of the greater risk of severe measles in such cases.

Table 2.31 Measles vaccination recommendations

Age

In emergency situations, all children from 6 months to 14 years of age should be immunized, with a minimum age range of 6 months to 4 years if resources are limited. In stable situations, measles vaccine is usually given between 9 and 12 months of age as part of the routine EPI

If the first dose is given at 6-8 months of age, a second dose must be given at 9 months of age.

More than one dose can be administered to an individual, as it does no harm and can strengthen immunity; it is a waste of vaccine, however

Route

Subcutaneous injection, usually in the arm, using a new sterile disposable needle (23 gauge) and syringe for each individual

Reactions

Some 5-15% of those vaccinated develop a fever and rash

Side-effects

A small number of cases of encephalitis have been reported

Contraindications

Pregnancy

Instructions for carers

The carer should be told that fever and rash may occur; it should be explained that this is a very mild form of the disease and, unless the temperature is high, there is no need for special action

Records

Each individual should receive a card stating the vaccine given and if a further dose is required

The name, date of birth, sex and location of each vaccinated individual should be recorded in an appropriate vaccine register

Storage

Measles vaccine is very sensitive to heat and should be stored at a temperature of 2-8 °C (usually on the top shelf of the fridge or in a vaccine carrier)

Reconstitution

Reconstitute with the sterile water that accompanies the vaccine; follow the instructions given on the vial, always check that the vaccine is within its expiry date before reconstitution; unused reconstituted vaccines must be discarded after 8 hours

Storage once reconstituted

The reconstituted vaccine should be placed in the circular hollow of the icepack in a shady place

The WHO/UNICEF global measles elimination strategy recommends that a second opportunity for measles revaccination should be offered to all children from 9 months through 14 years, with a minimum interval of one month between the 2 doses.

The WHO/UNICEF global measles elimination strategy recommends that a second opportunity for measles revaccination should be offered to all children from 9 months through 14 years, with a minimum interval of one month between the 2 doses.

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