Children with HIV have higher mortality and morbidity rates in their first 2 years of life than adults if untreated. Approximately 80% of untreated infants, well at 6 weeks of age, will progress to AIDS-defining illnesses within 6 – 12 months (3). 

The mechanism behind these concerning data remains unclear, however, it may be due to the ‘normal’ physiological immaturity of the infant’s immune system (4).  Tobin and Aldrovandi (2013) note that: 

Regardless of the level of CD4+ T cells or plasma viremia, younger children are at      greater risk of death or progression to AIDS compared to their older counterparts […]. A 1-year-old child with 10% CD4+ T cells has a 40% risk of progression to AIDS and 20% risk of death within 12 months (4, p. 149). 

These authors explain further that factors contributing to the high level of viraemia in young children might include ‘an increased susceptibility of infant cells to HIV-1 infection and shared HLA alleles between mother and child, so that the virus is preselected for fitness in the infant’ (4, p. 149).    

Acute HIV infection in adults is characterised by high viraemia, which rapidly declines. In contrast, perinatally infected infants do not show the same fall in viraemia. HIV viral loads only start to decline beyond infancy, to reach an ‘adult’ set point by approximately 5 years of age (4).