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Population Impact and Effectiveness of Monovalent Rotavirus Vaccination in Urban Malawian Children 3 Years after Vaccine Introduction: Ecological and Case-Control Analyses

Wednesday, 8th of June 2016

Clin Infect Dis. 2016 May 1;62 Suppl 2:S213-9. doi: 10.1093/cid/civ1183.

Population Impact and Effectiveness of Monovalent Rotavirus Vaccination in Urban Malawian Children 3 Years after Vaccine Introduction: Ecological and Case-Control Analyses

Bar-Zeev N1, Jere KC1, Bennett A1, Pollock L1, Tate JE2, Nakagomi O3, Iturriza-Gomara M4, Costello A5, Mwansambo C6, Parashar UD2, Heyderman RS7, French N1, Cunliffe NA4; Vaccine Effectiveness and Disease Surveillance Programme, Malawi (VACSURV) Consortium.

Collaborators (8)

Beard J, Crampin AC, King C, Lewycka S, Mvula H, Phiri T, Verani JR, Whitney CG.

Author information

1Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Blantyre Institute of Infection and Global Health, University of Liverpool, United Kingdom.

2Epidemiology Branch, Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.

3Graduate School of Biomedical Sciences, Nagasaki University, Japan.

4Institute of Infection and Global Health, University of Liverpool, United Kingdom.

5Institute of Global Health, University College London, United Kingdom.

6Ministry of Health, Lilongwe, Malawi.

7Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Blantyre Liverpool School of Tropical Medicine Division of Infection and Immunity, University College London, United Kingdom.

Abstract below; full text is at http://cid.oxfordjournals.org/content/62/suppl_2/S213.long

BACKGROUND:

Rotavirus vaccines have been introduced in many low-income African countries including Malawi in 2012. Despite early evidence of vaccine impact, determining persistence of protection beyond infancy, the utility of the vaccine against specific rotavirus genotypes, and effectiveness in vulnerable subgroups is important.

METHODS:

We compared rotavirus prevalence in diarrheal stool and hospitalization incidence before and following rotavirus vaccine introduction in Malawi. Using case-control analysis, we derived vaccine effectiveness (VE) in the second year of life and for human immunodeficiency virus (HIV)-exposed and stunted children.

RESULTS:

Rotavirus prevalence declined concurrent with increasing vaccine coverage, and in 2015 was 24% compared with prevaccine mean baseline in 1997-2011 of 32%. Since vaccine introduction, population rotavirus hospitalization incidence declined in infants by 54.2% (95% confidence interval [CI], 32.8-68.8), but did not fall in older children. Comparing 241 rotavirus cases with 692 test-negative controls, VE was 70.6% (95% CI, 33.6%-87.0%) and 31.7% (95% CI, -140.6% to 80.6%) in the first and second year of life, respectively, whereas mean age of rotavirus cases increased from 9.3 to 11.8 months. Despite higher VE against G1P[8] than against other genotypes, no resurgence of nonvaccine genotypes has occurred. VE did not differ significantly by nutritional status (78.1% [95% CI, 5.6%-94.9%] in 257 well-nourished and 27.8% [95% CI, -99.5% to 73.9%] in 205 stunted children;P= .12), or by HIV exposure (60.5% [95% CI, 13.3%-82.0%] in 745 HIV-unexposed and 42.2% [95% CI, -106.9% to 83.8%] in 174 exposed children;P= .91).

CONCLUSIONS:

Rotavirus vaccination in Malawi has resulted in reductions in disease burden in infants <12 months, but not in older children. Despite differences in genotype-specific VE, no genotype has emerged to suggest vaccine escape. VE was not demonstrably affected by HIV exposure or stunting.

© The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America.