|An evaluation of measles revaccination among school-entry-aged children
|Watson J C, Pearson J A, Markowitz L E, Baughman A L, Erdman D D, Bellini W J, Baron R C, Fleming D W
This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.
Two dose measles vaccination schedule.
Economic study type
Children aged 4-6 years who had received one dose of measles vaccine at age 15-17 months and who had been enrolled at the time in the study HMO (see below) and still were at the time of the study. These children had never been diagnosed as having measles, cancer, leukemia or a serious defect of the immune system.
The setting was the community: a large HMO providing health services to 20% of the population of Portland, Oregon, USA.
Dates to which data relate
The effectiveness data corresponded to 1990, whereas the dates for the resource data and the price year were not reported.
Source of effectiveness data
Link between effectiveness and cost data
Cost estimation was undertaken retrospectively on the study cohort.
A total of 679 children whose parents accepted the invitation to participate from an original eligible group of 2,305, were included in the study and underwent initial antibody testing. Thirty-seven patients were found to be seronegative and were re-vaccinated.
Single-centred case series. Seroprevalence study on a cohort of children whose parents responded to the invitation (679/2305). The duration of follow-up (time at which post re-vaccination serum was drawn for antimeasles immunoglobulin M (IgM) testing) was 12 to 33 days (median 14 days).
Analysis of effectiveness
The outcome of effectiveness was seroconversion after revaccination (assayed by ELISA) and defined as IGM response.
No differences in age, sex, zip code, or age at and time since first MMR were detected between participants and non-responders to the invitation. Of the 37 seronegative children, 36 (97%) responded by seroconversion. Maternal education level was the only factor significantly associated with non-response to initial vaccination (p < 0.01).
Revaccination substantially reduces the pool of susceptible children.
Measure of benefits used in the economic analysis
Cases of probable measles susceptibility avoided with revaccination.
The cost of vaccination based on public health clinics' fees (MMR vaccine and administration fee) in Oregon were calculated. The price year and quantities of resource use were not reported.
Estimated benefits used in the economic analysis
No differences in age, sex, zip code, or age at and time since first MMR were detected between participants and non-responders to the invitation. Of the 37 seronegative children, 36 (97%) responded by seroconversion. Maternal education level was the only factor significantly associated with non-response to initial vaccination (P<0.01). Thus, of 679 patients re-vaccinated, an additional 36 (5%) seroconversions were achieved relative to the initial vaccination option.
The total cost of vaccination for the 679 participants (initial vaccinations) was $14,938, whereas the revaccination of those patients would have incurred double that cost.
Synthesis of costs and benefits
Vaccinating the 679 children once would cost $23 per seroconversion. Vaccinating only children whose mother had completed college education would cost $250 per seroconversion. Vaccinating all 679 twice would cost $415 per seroconversion gained, relative to the single vaccination strategy.
Revaccination reduced the pool of children who were susceptible to measles. Although the cost of $415 per seroconversion was high, a two dose schedule should significantly reduce the risk and impact of outbreaks of measles in vaccinated cohorts.
The economic component could have been designed and reported in a more informative way. Neither the quantities of resources consumed nor their costs were clearly reported. The most significant parts of the study are the confirmation that two dose-measles vaccination affords good immunity and the discovery, in mothers' educational level, of a possible confounder for seroconversion. The reasons for this finding are explored but not adequately explained in the text. The study results are unlikely to be internally valid due to the study design used. An important assumption made was that all children were seronegative for neutralizing antibody by microneutralization at initial vaccination, and that such a finding is indicative of probable measles susceptibility.
Implications of the study
Further studies are needed in order validly to state the cost and effectiveness of measles revaccination relative to initial vaccination alone.
Watson J C, Pearson J A, Markowitz L E, Baughman A L, Erdman D D, Bellini W J, Baron R C, Fleming D W. An evaluation of measles revaccination among school-entry-aged children. Pediatrics 1996; 97(5): 613-618
Subject indexing assigned by NLM
Antibodies, Viral /biosynthesis /blood; Case-Control Studies; Child; Child, Preschool; Cohort Studies; Cost-Benefit Analysis; Disease Outbreaks /prevention & Educational Status; Enzyme-Linked Immunosorbent Assay; Evaluation Studies as Topic; Female; Humans; Immunization Schedule; Immunization, Secondary /economics; Immunoglobulin G /blood; Immunoglobulin M /analysis; Male; Measles Vaccine /administration & Measles virus /immunology; Mothers; Neutralization Tests; Vaccination /economics; control; dosage /economics
Date bibliographic record published
Date abstract record published