Q&A: Measles Vaccination Campaigns
Posted by chads on November 28, 2006
For an explanation of the Q&A series, look here.
Q: How effective are mass measles vaccination campaigns?
Methods: A PubMed search was done using the words “measles immunization campaigns.” 169 Articles were found. Of those, 15 were thought to be applicable.
A: Measles vaccination campaigns can reduce measles cases by as much as 90%, and eradication of the disease is a possibility with effective, comprehensive campaigns.
A September, 2005 Lancet article reported on 19 African countries that had completed measles immunization activities in children aged 9 months to 14 months between 2000 and June, 2003. 82·1 million children were targeted for vaccination in 12 countries and follow-up immunization in seven countries, reaching an average of 97% of the targeted population. The average decline in the number of reported measles cases was 91%. They also estimated the percentage decline in annual measles deaths to be around 20% (90 043 of 454 000).
There were several limitations to this study. First, measles cases were defined based on a clinical criteria (an illness characterised by rash, fever, and cough, coryza, or conjunctivitis), or “any illness that a clinician suspected to be measles.” Diagnosis (and, therefore, reporting) of measles cases, then, depended on the clinicians’ training, as well as possible discrepancies in the very definition of measles. Number of deaths averted were also estimated based on the percentage of measles deaths from prior years.
A 2003 article in the Journal of Infectious Diseases reported 39% decrease in measles cases in Uganda. However, only children aged 6 months to 5 years were targeted.
A report by the CDC estimated that cases of measles fell from 8,762 to 2,574 (about 70%) in 2002 after a mass immunization campaign in Afghanistan. An estimated 82% of the targeted 6 months-12 years population was reached.
Complications of vaccinations are rare, but have been reported and discussed in Brazil, where meningitis was reported, and Afghanistan, where abscesses formed. Reports also stress the importance of immunizing all of the 9-month to 15 year-old age group, using sterile needles, having the necessary infrastructure in place, as well as considering the impact that the campaign has on the underlying health system.