MEASLES ELIMINATION IN THE AMERICAS: A COMPARISON BETWEEN COUNTRIES WITH A ONE-DOSE AND TWO-DOSE ROUTINE VACCINATION SCHEDULE.

Tuesday, 27th of August 2013

[source]Journal of Infectious Diseases[|source]

This report found no impact of a second routine measles dose in the Region of the Americas, but quickly added that their findings might not be applicable to other countries and regions. In particular, the authors report that a second routine dose might have greater impact when administered at 2 years of age and in countries and regions with lower measles vaccine coverage than was achieved in the Region of the Americas from routine vaccination and from vaccination campaigns. As other regions and countries come closer to achieving measles elimination goals, more evidence is needed to determine the most-effective means and timing of delivering a second routine dose of measles vaccine. Future research could in addition focus on the role of a second routine dose on sustaining measles elimination. More details available at:  http://jid.oxfordjournals.org/content/204/suppl_2/S748.long

 

Abstract

BACKGROUND: The Region of the Americas eliminated measles in 2002 through high first-dose routine measles vaccine coverage and vaccination campaigns every 4-6 years; a second routine dose at school entry was added in some countries. The impact of this second routine dose on measleselimination was evaluated.

METHODS: Data on socioeconomic factors, demographic characteristics, vaccination coverage, and the estimated proportion of children (<15 years of age) susceptible to measles were compiled. Countries were grouped using propensity score methods, and Kaplan-Meier curves were used to compare time to measles elimination between countries with a 1-dose schedule and those with a 2-dose schedule.

RESULTS: One-dose (n = 14) and 2-dose (n = 7) countries did not differ with respect to median routine first-dose measles vaccine coverage, median coverage for 3 measles campaigns, or estimated percentage of susceptible children after routine first vaccination dose and campaigns. Compared with 1-dose countries, 2-dose countries had higher median gross national income per capita (P = .002), percentage of population living in urban areas (P = .04), and female literacy (P = .01), as well as lower infant mortality (P = .007); however, no differences in time to elimination were found.

CONCLUSIONS: One-dose and 2-dose countries had similar times to measles elimination despite socioeconomic differences between their populations. A second routine dose might not have hastened measles elimination, because threshold immunity needed to eliminate measles was achieved with high first routine dose coverage and vaccination campaigns. Further research will be needed to determine the applicability of these findings to other regions.