Mortality associated with seasonal and pandemic influenza and respiratory syncytial virus among children <5 years of age in a high HIV prevalence setting--South Africa, 1998-2009

Abstract

Background: There are few published data describing the mortality burden associated with influenza and respiratory syncytial virus (RSV) infection in children in low- and middle-income countries and particularly from Africa and settings with high prevalence of human immunodeficiency virus (HIV).

Methods: We modeled the excess mortality attributable to influenza (seasonal and pandemic) and RSV infection by applying Poisson regression models to monthly all-respiratory and pneumonia and influenza deaths, using national influenza and RSV laboratory surveillance data as covariates. In addition, we estimated the seasonal influenza- and RSV-associated deaths among HIV-infected and -uninfected children using Poisson regression models that incorporated HIV prevalence and highly active antiretroviral therapy coverage as covariates.

Results: In children <5 years of age, the mean annual numbers of seasonal influenza- and RSV-associated all-respiratory deaths were 452 (8 per 100 000 person-years [PY]) and 546 (10 per 100 000 PY), respectively. Infants <1 year of age experienced higher mortality rates compared with children 1-4 years of age for both influenza (22 vs 5 per 100 000 PY) and RSV (35 vs 4 per 100 000 PY). HIV-infected compared with HIV-uninfected children <5 years of age were at increased risk of death associated with influenza (age-adjusted relative risk [aRR], 11.5; 95% confidence interval [CI], 9.6-12.6) and RSV (aRR, 8.1; 95% CI, 6.9-9.3) infection. In 2009, we estimated 549 (11 per 100 000 PY) all-respiratory influenza A(H1N1)pdm09-associated deaths among children aged <5 years.

Conclusions: Our findings support increased research efforts to guide and prioritize interventions such as influenza vaccination and HIV prevention in low- and middle-income countries with high HIV prevalence such as South Africa.

Keywords: HIV; South Africa; influenza; mortality; respiratory syncytial virus.

Figure 1.

Mortality rate, detection of influenza and respiratory syncytial virus, human immunodeficiency virus (HIV) prevalence, and highly active antiretroviral therapy (HAART) coverage in children <5 years of age in South Africa, 1998–2009. A, Observed all-respiratory deaths, predicted deaths, and predicted baseline by month (Poisson model 1). B, Monthly detection rate (ie, monthly number of positive specimens divided by total specimens) of influenza and respiratory syncytial virus (all ages). C, Annual HIV prevalence and HAART coverage obtained from the Actuarial Society of South Africa AIDS and Demographic Model [24]. Observed deaths [31] are adjusted using estimates of death underreporting from 1998 to 2006 [33].