Maternal HIV-positive status shown to be linked to poor vaccination coverage in children

Children born to HIV-positive mothers were 25 to 40% less likely to be vaccinated for childhood diseases, according to findings from a study based on data from rural KwaZulu-Natal, presented at the Fourth South African AIDS Conference in Durban in early April.

The distance to mobile clinics was also a significant determinant of vaccination. Wealth index was a significant determinant for vaccinations given once, but for those vaccinations that required three visits to healthcare facilities, coverage was mediated by other factors, such as distance to the nearest road, since mothers have to overcome transport challenges more than once to complete the course of vaccinations.

Globally, vaccinations have led to reduced morbidity and mortality in children, with an estimated 2.9 million potential deaths prevented by vaccinations between 2000 and 2007, according to the World Health Organization.

However a cross-sectional study conducted among pregnant women in Rakai, Uganda, showed that children born to HIV-infected mothers were significantly less likely to be vaccinated (OR=2.21, 95% CI; 1.14 to 4.29).

To investigate the relationship between immunisation status of children and maternal HIV status, 2431 children in the Hlabisa district were included in a regression analysis by James Ndirangu from the Africa Centre for Health and Population Studies, at the University of KwaZulu-Natal.

The sample included all children born between January 2004 and December 2005 and resident in the area covered by the Africa Centre’s demographic survey, an ongoing research project in a rural district in northern KwaZulu-Natal.

Maternal HIV status was found to be positive for 890 (36.6%) and negative for 275 (11.5%) of the mothers. More than half of the mothers (52.1%) did not know their HIV-status.

Data were collected from each child’s Road to Health (RTH) card and mothers were also requested to recall the vaccinations of their children.

After adjusting for maternal age, maternal education, household wealth and distance to the nearest road, mobile clinic or fixed clinic, it was found that children born to HIV-positive mothers were 40% less likely to have received a BCG vaccination than those born to HIV-negative mothers.

For the polio, DTP and hepatitis B vaccinations, which must be administered three times, it was found that children born to HIV-positive mothers were 36% less likely to have received the vaccinations than those born to HIV-negative mothers (p = 0.05).

Possible reasons for HIV-positive mothers to be less likely to vaccinate their children may be due to maternal HIV-related diseases and weakness. Another factor that may be contributing to the lower rate of immunisation is the time and resources mothers have to devote to accessing antiretroviral treatment, especially in this rural setting. Fear of stigmatisation is also a suggested factor, with mothers not wanting to attend facilities where their status may be known.

Distance to mobile clinic was also a significant determinant of vaccination. Sixty-five per cent of mothers in the study area walk for one hour or more to the nearest clinic.

The median distance to the nearest road was 2.01 km, while the median distance to the nearest mobile clinic was as much as 5.77km and to the nearest fixed clinic was 3.11km. The relative distance to mobile clinics as opposed to fixed clinics is also a contributing factor, as fixed clinics provide comprehensive primary care while mobile clinics are specifically for vaccination, family planning and antenatal care.

Future interventions to improve vaccination coverage should take into account the relationship between maternal HIV status and vaccination coverage. Specific vaccination campaigns which target HIV-positive mothers should be carried out at community and individual level to improve coverage. This is especially important given that the children of many of the HIV-positive mothers may be HIV-positive themselves and hence more likely to fall ill with the diseases they need to be vaccinated against.