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EQUALITY OF ACCESS FOR MEASLES VACCINATION/ AEROSOL VACCINATION AGAINST MEASLES

Friday, 28th of March 2008 Print

CHILD SURVIVAL UPDATE 13/2008: THREE ON MEASLES/READER FEEDBACK
  
 1) HIGHER MEASLES VACCINATION COVERAGE AND EQUALITY OF ACCESS
 
 In their review of data from 21 Demographic and Health Surveys (first
 attachment), Meheus and van Doorslaer conclude that "most countries have
 experienced an improvement in their mean measles immunization rate, but
 that this improvement was often unequally distributed across wealth groups,
 disfavouring the poor in all countries." How can this be, when vaccinations
 are given free? Inequality of access may be linked either to user fees (in
 some countries) or, in most countries, the relatively thin spread of health
 facilities in remote and inaccessible areas, which are typically less
 wealthy than urban and peri-urban areas.
 
  As shown in the CDC study from Kenya, mass campaigns
 tend to improve both coverage and equity. Depending on the country,
 guaranteeing access may require one or more of the following:
 
 i) outreach and mobile strategies as part of routine vaccination
 ii) periodic Child Health Days designed to reach everyone, especially
 those in remote areas
 iii) measles catch-up and follow-up campaigns, with special strategies to
 reach the least accessible populations..
 
 Full text of these articles is available to subscribers of the journals
 where they appeared.
 
 
 2) AEROSOLIZED MEASLES VACCINE, GLOBALLY AND IN SOUTH AFRICA
 
 The abstract below describes progress in a new vaccine delivery technology.
 Thanks to A. Henao-Restrepo for bringing it to my attention. Full text is
 available to Vaccine subscribers.
 

1: Vaccine. 2008 Jan 17;26(3):383-98. Epub 2007 Nov 26
 
 Immunogenicity and safety of aerosolized measles vaccine: systematic
 review and meta-analysis
 Low N, Kraemer S, Schneider M, Restrepo AM.
 
 
 Insititute of Social and Preventive Medicine, University of Bern,
 Bern, Switzerland. low@ispm.unibe.ch
 
 
 Aerosols are the most promising non-injectable method of measles
 vaccination studied so far and their efficacy is thought to be
 comparable to injected vaccine. We conducted a systematic review up
 to May 2006 to examine the immunogenicity and safety of aerosolized
 measles vaccine (Edmonston-Zagreb or Schwarz strains) 1 month or more
 after vaccination. Where possible we estimated pooled serological
 response rates and odds ratios (with 95% confidence intervals, CI)
 comparing aerosolized and subcutaneous vaccines in children in three
 age groups and adults. We included seven randomized trials, four
 non-randomized trials and six uncontrolled studies providing
 serological outcome data on 2887 individuals. In children below 10
 months, the studies were heterogeneous. In four comparative studies,
 seroconversion rates were lower with aerosolized than with
 subcutaneous vaccine and in two of these the difference was unlikely
 to be due to chance. In children 10-36 months, the pooled
 seroconversion rate with aerosolized vaccine was 93.5% (89.4-97.7%)
 and 97.1% (92.4-100%) with subcutaneous vaccine (odds ratio 0.27,
 0.04-1.62). In 5-15-year olds the studies were heterogeneous. In all
 comparative studies aerosolized vaccine was more immunogenic than
 subcutaneous. Reported side effects were mild. Aerosolized measles
 vaccine appears to be equally or more immunogenic than subcutaneous
 vaccine in children aged 10 months and older. Large randomized trials
 are needed to establish the efficacy and safety of aerosolized
 measles vaccine as primary and booster doses.
 
 Immunization of six-month-old infants with different doses of
 Edmonston-Zagreb and Schwarz measles vaccines. [N Engl J Med.
 1990]
 Alternative routes of measles immunization: a review.
 [Biologicals. 1997]
 Response to different measles vaccine strains given by aerosol
 and subcutaneous routes to schoolchildren: a randomised trial.
 [Lancet. 2000]
 Aerosolized measles and measles-rubella vaccines induce better
 measles antibody booster responses than injected vaccines:
 randomized trials in Mexican schoolchildren. [Bull World Health
 Organ. 2002]
 Immunogenicity of aerosol measles vaccine given as the primary
 measles immunization to nine-month-old Mexican children.
 [Vaccine. 2006]
 
 
 In a research report from South Africa, Dilraj and colleagues show
 persistence of satisfactory antibody levels in those vaccinated by aerosol
 compared to subcutaneous routes. "Measles revaccination by aerosol evokes a
 stronger and much longer lasting antibody response than injected vaccine
 and should thus provide more durable protection against measles."
 
 
 
 3) MEASLES VACCINATION AND SUBACUTE SCLEROSING PANENCEPHALITIS
 
 The measles vaccine, alone and in combination, has no lack of critics.
 Here, Campbell and colleagues put paid to the notion that measles is
 causally linked to SSPE. On the contrary, rises in measles vaccination are
 associated with steep declines in the incidence of SSPE.
 
 Of course, measles vaccination does not protect against SSPE among those
 who contract measles in the perinatal period. However, the number of
 perinatal measles cases shrinks as vaccination coverage grows. The end of
 measles may lead to the end of SSPE.
 
1: Int J Epidemiol. 2007 Dec;36(6):1334-48. Epub 2007 Nov 23.
 
 Review of the effect of measles vaccination on the epidemiology of SSPE
 Campbell H, Andrews N, Brown KE, Miller E.
 
 
 Immunisation Department, Health Protection Agency Centre for
 Infections, 61 Colindale Avenue, London NW9 5EQ, UK.
 
 
 BACKGROUND: When measles vaccines were widely introduced in the
 1970s, there were concerns that they might cause subacute sclerosing
 panencephalitis (SSPE): a very rare, late-onset, neurological
 complication of natural measles infection. Therefore, SSPE registries
 and routine measles immunization were established in many countries
 concurrently. We conducted a comprehensive review of the impact of
 measles immunization on the epidemiology of SSPE and examined
 epidemiological evidence on whether there was any vaccine-associated
 risk. METHODS: Published epidemiological data on SSPE, national SSPE
 incidence, measles incidence and vaccine coverage, reports of SSPE in
 pregnancy or shortly post partum were reviewed. Potential adverse
 relationships between measles vaccines and SSPE were examined using
 available data. RESULTS: Epidemiological data showed that successful
 measles immunization programmes protect against SSPE and, consistent
 with virological data, that measles vaccine virus does not cause
 SSPE. Measles vaccine does not: accelerate the course of SSPE;
 trigger SSPE or cause SSPE in those with an established benign
 persistent wild measles infection. Evidence points to wild virus
 causing SSPE in cases which have been immunized and have had no known
 natural measles infection. Perinatal measles infection may result in
 SSPE with a short onset latency and fulminant course. Such cases are
 very rare. SSPE during pregnancy appears to be fulminant. Infants
 born to mothers with SSPE have not been subsequently diagnosed with
 SSPE themselves. CONCLUSIONS: Successful measles vaccination
 programmes directly and indirectly protect the population against
 SSPE and have the potential to eliminate SSPE through the elimination
 of measles. Epidemiological and virological data suggest that measles
 vaccine does not cause SSPE.
 
 
 The epidemiology of subacute sclerosing panencephalitis in
 England and Wales 1990-2002. [Arch Dis Child. 2004]
 Frequency, serodiagnosis and epidemiological features of
 subacute sclerosing panencephalitis (SSPE) and epidemiology and
 vaccination policy for measles in the Federal Republic of
 Germany (FRG). [Dev Biol Stand. 1978]
 Subacute sclerosing panencephalitis in Bulgaria (1978-2002).
 [Neuroepidemiology. 2004]
 [Epidemiological aspects of SSPE] [Nippon Rinsho. 2007]
 Measles, measles vaccination, and risk of subacute sclerosing
 panencephalitis (SSPE).. [Neurology. 1983]
 
 4) READER FEEDBACK
 
 From reader Jules Millogo comes this observation on a previous posting on
 measles vaccination:
 
 "A small comment on your first sentence: 'Except for Breast Feeding, which
 is free...'
 
 "I understand the point made and I don't want to just argue with my friend
 Bob for the sake of argument. However, simple statements like this disvalue
 the effort and time of women who rear children. It is true that nobody is
 thinking about paying a woman for breast feeding, but this does not mean
 that it does not come at a cost for the women. It is time we recognize the
 fact that women work hard for the health and nutrition of the entire
 family."
 
 Hmm. True, but Mrs. Davis tells me that breast feeding yields benefits for
 the mother, especially in terms of bonding to the infant. So breast feeding
 is probably a benefit to the mother, though entailing intangible costs.
 
 Good reading.
 
 BD

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