Evaluating the impact of the HIV pandemic on measles control and elimination.
OBJECTIVE
To estimate the impact of the HIV pandemic on vaccine-acquired population immunity to measles virus because high levels of population immunity are required to eliminate transmission of measles virus in large geographical areas, and HIV infection can reduce the efficacy of measles vaccination.


METHODS
A literature review was conducted to estimate key parameters relating to the potential impact of HIV infection on the epidemiology of measles in sub-Saharan Africa; parameters included the prevalence of HIV, child mortality, perinatal HIV transmission rates and protective immune responses to measles vaccination. These parameter estimates were incorporated into a simple model, applicable to regions that have a high prevalence of HIV, to estimate the potential impact of HIV infection on population immunity against measles.


RESULTS
The model suggests that the HIV pandemic should not introduce an insurmountable barrier to measles control and elimination, in part because higher rates of primary and secondary vaccine failure among HIV-infected children are counteracted by their high mortality rate. The HIV pandemic could result in a 2-3% increase in the proportion of the birth cohort susceptible to measles, and more frequent supplemental immunization activities (SIAs) may be necessary to control or eliminate measles. In the model the optimal interval between SIAs was most influenced by the coverage rate for routine measles vaccination. The absence of a second opportunity for vaccination resulted in the greatest increase in the number of susceptible children.


CONCLUSIONS
These results help explain the initial success of measles elimination efforts in southern Africa, where measles control has been achieved in a setting of high HIV prevalence.
Helfand
Rita F
RF
Respiratory and Enteric Viruses Branch, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop A-30, Atlanta, GA 30333, USA. rzh7@cdc.gov
Moss
William J
WJ
Harpaz
Rafael
R
Scott
Susana
S
Cutts
Felicity
F
D000293:Adolescent; D000328:Adult; D017954:Africa South of the Sahara / Q000453:epidemiology; D000937:Antigen-Antibody Reactions; D002648:Child; D002675:Child, Preschool; D015658:HIV Infections / Q000150:complications* / Q000401:mortality; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008457:Measles / Q000276:immunology / Q000401:mortality / Q000517:prevention & control; D008458:Measles Vaccine; D015995:Prevalence
D008458:Measles Vaccine