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. 2018 Apr 3;66(8):1270-1275.
doi: 10.1093/cid/cix974.

Genotype-Specific Measles Transmissibility: A Branching Process Analysis

Sarah F Ackley  1   2 , Jill K Hacker  3 , Wayne T A Enanoria  2 , Lee Worden  1 , Seth Blumberg  1   4 , Travis C Porco  1   2   5 , Jennifer Zipprich  3
Affiliations

Genotype-Specific Measles Transmissibility: A Branching Process Analysis

Sarah F Ackley et al. Clin Infect Dis. .

Abstract

Background: Substantial heterogeneity in measles outbreak sizes may be due to genotype-specific transmissibility. Using a branching process analysis, we characterize differences in measles transmission by estimating the association between genotype and the reproduction number R among postelimination California measles cases during 2000-2015 (400 cases, 165 outbreaks).

Methods: Assuming a negative binomial secondary case distribution, we fit a branching process model to the distribution of outbreak sizes using maximum likelihood and estimated the reproduction number R for a multigenotype model.

Results: Genotype B3 is found to be significantly more transmissible than other genotypes (P = .01) with an R of 0.64 (95% confidence interval [CI], .48-.71), while the R for all other genotypes combined is 0.43 (95% CI, .28-.54). This result is robust to excluding the 2014-2015 outbreak linked to Disneyland theme parks (referred to as "outbreak A" for conciseness and clarity) (P = .04) and modeling genotype as a random effect (P = .004 including outbreak A and P = .02 excluding outbreak A). This result was not accounted for by season of introduction, age of index case, or vaccination of the index case. The R for outbreaks with a school-aged index case is 0.69 (95% CI, .52-.78), while the R for outbreaks with a non-school-aged index case is 0.28 (95% CI, .19-.35), but this cannot account for differences between genotypes.

Conclusions: Variability in measles transmissibility may have important implications for measles control; the vaccination threshold required for elimination may not be the same for all genotypes or age groups.

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Figures

Figure 1.
Figure 1.
Estimated reproduction numbers for measles transmission: overall, genotype B3 vs non-B3 genotypes, and school-aged (age 5–18 years) vs non-school-aged index cases.
See this image and copyright information in PMC

References

    1. Orenstein WA, Samuel KL, Hinman AR. Summary and conclusions: measles elimination meeting, 16–17 March 2000. J Infect Dis 2004; 189(Suppl 1):S43–7. - PubMed
    1. Katz SL, De Quadros CA, Izurieta H, Venczel L, Carrasco P. Measles eradication in the Americas: progress to date. J Infect Dis 2004; 189(Suppl 1):S227–35. - PubMed
    1. Fiebelkorn AP, Redd SB, Gallagher K et al. Measles in the United States during the postelimination era. J Infect Dis 2010; 202:1520–8. - PubMed
    1. Blumberg S, Enanoria WT, Lloyd-Smith JO, Lietman TM, Porco TC. Identifying postelimination trends for the introduction and transmissibility of measles in the United States. Am J Epidemiol 2014; 179:1375–82. - PMC - PubMed
    1. Zipprich J, Winter K, Hacker J, Xia D, Watt J, Harriman K; Centers for Disease Control and Prevention (CDC). Measles outbreak—California, December 2014-February 2015. MMWR Morb Mortal Wkly Rep 2015; 64:153–4. - PMC - PubMed

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