Abstract
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.
Highlights
MethodsQueen Elizabeth Central Hospital (QECH) is a governmentfunded teaching hospital for the southern region of Malawi, and provides free healthcare to a population of about 1.3 million persons
Rotavirus vaccines have been introduced in many low-income African countries including Malawi in 2012
Among vaccine age-eligible infants
Summary
QECH is a governmentfunded teaching hospital for the southern region of Malawi, and provides free healthcare to a population of about 1.3 million persons It is the referral facility for a network of 23 government primary health centers. Study nurses actively recruited children in the Accident and Emergency Department Monday through Friday, and selectively sought to capture all admitted children and those with short-stay (approximately 4 hours) for observed oral rehydration. During both surveillance periods, we collected stool for rotavirus testing by enzyme immunoassay (EIA) (Rotaclone, Meridian Bioscience, Cincinnati, Ohio). Children whose mother’s status was unknown and who themselves had a negative rapid test were considered unexposed
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