Vaccine-Preventable Diseases

Overview

Only measles immunization should be part of the initial emergency relief effort; however, a complete EPI should be planned as an integral part of an ongoing long-term health program.

Diphtheria, tetanus toxoids (TT) and pertussis vaccine (DTP), oral polio vaccine (OPV), and bacille Calmette-Guerin (BCG) vaccinations are recommended. None should not be undertaken, however, unless the following criteria are met: the population is expected to remain stable for at least 3 months; the operational capacity to administer vaccine is adequate, and the program can be integrated into the national immunization program within a reasonable length of time.

It is essential that adequate immunization records be kept. At the very minimum, personal immunization cards (i.e., "Road to Health" cards) should be issued. In addition, a central register of all immunizations is desirable.

Measles

Priority. Measles vaccination campaigns should be assigned the highest priority early in emergency situations. Measles immunization programs should begin as soon as the necessary personnel, vaccine, cold chain equipment, and other supplies are available. Measles immunization should not be delayed until other vaccines become available or until cases of measles have been reported.

In refugee populations fleeing from countries with high immunization coverage rates, measles immunization should still be accorded high priority. Studies of urban populations (e.g., Kinshasa, Zaire) and densely populated refugee camps (e.g., camps in Malawi) have shown that large outbreaks of measles may still occur even if vaccine coverage rates exceed 80%. For example, in a camp of 50,000 refugees, approximately 10,000 would be children less than 5 years of age. If the vaccine coverage rate was 80% and vaccine efficacy was 90%, approximately 2,800 children in this camp would still be susceptible to measles. In addition, certain countries achieved high coverage in the 12 to 23 month age group, leaving large numbers of older children unprotected.

Program management. Responsibilities for each aspect of the immunization program need to be explicitly assigned to agencies and persons by the coordination agency.

The national EPI should be involved from the outset of the emergency. National guidelines regarding immunization should be applied in refugee settings.

A pre-immunization count should be conducted to estimate the number of children eligible for vaccination. This should not be allowed, however, to delay the start of the vaccination program.

Choice of vaccine. The standard Schwarz vaccine is recommended. The use of medium or high titer Edmonston-Zagreb (E-Z) vaccine is not yet recommended for refugee populations, since there are still concerns about its safety.

Target population. During the emergency phase, defined as that time during which the CMR is higher than 1/10,000/day, all children ages 6 months-5 years should be vaccinated upon arrival at the camp.

In long-term refugee health programs, vaccination should be targeted at all children ages 9 months-5 years, except during outbreaks when the lower age limit should again be dropped to 6 months.

Any child who has been vaccinated between the ages of 6 and 9 months should be revaccinated as soon as possible after reaching 9 months of age, or 1 month later if the child was 8 months old at first vaccination.

If there is insufficient vaccine available to immunize all susceptible children, the immunization program should be targeted at the following high-risk groups, in order of priority:

Older children, adolescents, and adults may also need to be immunized if surveillance data show that these groups are being affected during an outbreak.

Undernutrition is not a contraindication for measles vaccination! Undernutrition should be considered a strong indication for vaccination. Similarly, fever, respiratory tract infection, and diarrhea are not contraindications for measles vaccination. Unimmunized persons who are infected with HIV should receive the vaccine. Measles vaccine should also be administered in the presence of active TB (1).

Outbreak control. Measles immunization programs should not be stopped or postponed because of the presence of measles in the camp or settlement. On the contrary, immunization efforts should be accelerated.

Among persons who have already been exposed to the measles virus, measles vaccine may provide some protection or modify the clinical severity of the disease, if administered within 3 days of exposure.

Isolation of patients with measles is not indicated in an emergency camp setting.

Case management. All children who develop clinical measles in refugee camps should have their nutritional status monitored and be enrolled in a feeding program if indicated.

Children with measles complications should be administered standard treatment, e.g., ORT for diarrhea and antibiotics for acute lower respiratory infection (ALRI).

If they have not received vitamin A during the previous month, all children with clinical measles should receive 200,000 IU vitamin A orally. Children less than 12 months of age should receive 100,000 IU. This should be repeated every 3 months as part of the routine vitamin A supplementation schedule.

Children with complicated measles (pneumonia, otitis, croup, diarrhea with moderate or severe dehydration, or neurological problems) should receive a second dose of vitamin A on day 2.

If any eye symptoms of vitamin A deficiency are observed (xerosis, Bitot's spots, keratomalacia, or corneal ulceration), the following treatment schedule should be followed:
200,000 IU oral vitamin A on day 1.
200,000 IU oral vitamin A on day 2.
200,000 IU oral vitamin A 1-4 weeks later.
Children less than 12 months of age receive half doses.

Diphtheria-tetanus-pertussis

Once a comprehensive EPI has been established, all children ages 6 weeks-5 years should receive three doses of DTP, 4-8 weeks apart.

Poliomyelitis

One dose of OPV should be administered at birth, followed by three doses 4-8 weeks apart to all children 6 weeks-5 years of age.

Tuberculosis

BCG vaccination should be offered as part of the comprehensive EPI, rather than as a separate TB program. One dose of BCG is administered subcutaneously at birth. Recommendations for TB control are presented in a separate section.

Neonatal tetanus

All women between the ages of 15-44 years should receive a full schedule of TT vaccination. Vaccination should commence at a younger age if girls less than 15 years of age commonly bear children in the refugee community. TT vaccination should be included as part of a standard antenatal care program. Female health workers should be employed to educate women about the need for the TT vaccination and to refer pregnant women to the antenatal care clinic. Although WHO recommends a 5-dose schedule for TT vaccination (see "WHO Tetanus Toxoid Vaccination Schedule"), the number of doses of TT administered varies from country to country. The schedule in refugee camps should be consistent with host country national policies.

Meningococcal meningitis

Surveillance. In areas where epidemics of meningococcal meningitis are known to occur, as in Africa's "meningitis belt," surveillance for meningitis should be a routine part of a HIS. Such surveillance requires a standard case definition, the identification (in advance) of laboratory facilities and a source of supplies (e.g., spinal needles, antiseptics, test tubes), and a clearly established reporting network.

Outbreak identification and control. If an outbreak of meningococcal meningitis is suspected, early priority should be given to the determination of etiology and serogroup. This may be accomplished through the use of latex agglutination tests. It is also important to determine antibiotic resistance patterns. Cerebral spinal fluid (CSF) or petechial washings should be placed in suitable transport media and kept at 37 C during transport to a local or regional laboratory with the capacity to perform the needed analysis. If transport media are unavailable, CSF specimens should be placed in a test tube and transported at body temperature as soon as possible.

After an outbreak has been confirmed, a presumptive diagnosis of meningococcal meningitis among persons with suggestive symptoms and signs can be made by visual inspection of CSF from lumbar punctures; CSF will appear cloudy in probable cases. Clinical characteristics include fever, severe headache, neck stiffness, vomiting, and photophobia.

Endemic rates of meningococcal disease vary by geographic area, season, and age; thus it is not possible to define a rate that can be applied universally to identify an epidemic disease. In one study, an average incidence rate of disease that exceeded 15 cases/100,000/week for a period of 2 consecutive weeks was predictive of an epidemic (defined as greater than 100 cases/100,000). Since this threshold may only be valid for populations greater than 100,000 and because the population in a refugee camp may be unknown, a doubling of the baseline number of cases from 1 week to the next over a period of 3 weeks may be used as a rough indicator of a meningitis outbreak.

Vaccination. Vaccination of refugees against meningococcal meningitis during non-epidemic periods is generally not considered to be an effective measure because of the short duration of protection in young children. If there are compelling reasons to believe that the refugee population is at high risk for an epidemic, preventive vaccination before the meningitis season may be warranted.

In the event of an outbreak, vaccination should be considered if the following criteria are met:

If it is logistically feasible, the household contacts of identified cases should be checked for vaccination status and immunized if necessary. It may be simpler to organize a mass immunization program.

Because cases of meningococcal meningitis are likely to cluster geographically within a refugee camp, it may be most efficient to focus the vaccination campaign on the affected area(s) first. Although the target group for immunization should be determined from the epidemiology of the specific outbreak, vaccination of children and young adults between the ages of 1-25 years will generally cover the at-risk population.

Chemoprophylaxis. Mass chemoprophylaxis is ineffective for control of epidemic meningococcal disease and is to be discouraged in a refugee setting.

If chemoprophylaxis is to be instituted, the following guidelines should be implemented: