Cape Town - Children may still be vulnerable to the cancer-causing hepatitis B virus despite having been inoculated against it at infancy, new research has revealed.
The study in the latest issue of SA Medical Journal showed that at an average age of six-and-a-half, most children had no immunity to the virus, leaving them at risk of acquiring infection.
Of more than 200 children treated for various cancers at Pretoria’s Steve Biko Academic Hospital between January 2012 and December last year, researchers found that 40 percent were not immune to the virus despite having been inoculated three times between the ages of six and 14 weeks.
HIV-positive children were worse off with 80 percent found to have no immunity to hepatitis B virus at all.
The study raises questions about the level of immunity some vaccines in the country’s Expanded Programme of Immunisation provide. It could also stir a debate on whether or not some vaccines need to be boosted later in life.
Hepatitis B, which is transmitted through blood contact and body fluids, mainly affects the liver. Chronic infection causes about 80 percent of liver cancers. The hepatitis B vaccine which was introduced in South Africa almost 20 years ago.
In 2010, 94 percent of the country’s children were reported to be fully immunised against hepatitis B in their first year, but this figure was disputed by the World Health Organisation, which noted that only 56 percent of children received all three doses.
In the latest study, while none of the patients analysed had active hepatitis B at initial screening, and only six had evidence of previous infection, about 77 percent of patients were found to have sub-optimal anti-hepatitis concentration in their bodies.
While there is no consensus about the necessary level of antibodies in immune-compromised patients, it is accepted that children with a normal immune response will be protected with 10ml of antibodies.
Fareed Ebrahim Omar, a co-author of the study from the paediatric haematology and oncology unit at Steve Biko Academic Hospital, called for active surveillance and continued screening of the virus, especially among people being treated for cancer. He also called for the boosting of hepatitis vaccination through combination with other anti-hepatitis preventative medication to protect patients against severe infection.
“The use of combined passive-active immunisation should be encouraged, especially in children with haematological malignancies and in HIV-infected children. Implementation of an effective screening and vaccination programme in the haematology and oncology units should protect all patients from hepatitis B.”
Cape Argus