There are currently new TB vaccine candidates in the pipeline that are being tested either to replace the BCG vaccine or to boost it. However, these new vaccines need to be carefully tested in humans and if effective, it will take years before these results are available.

BCG is the oldest vaccine currently in use in humans and was first administered to humans in 1921. According to the co-director of the SA TB Vaccine Initiative (SATVI) Dr Hassan Mahomed, the vaccine developers at the time found a child, administered the vaccine and when he failed to acquire TB declared it a success.

However, subsequent trials of BCG, one of the most famous being one in the United Kingdom in adolescents in the 1950s showed 80% protection. Ironically, a subsequent large trial in India showed zero protection.

‘€œSo, the efficacy against adult TB of the lungs is anything from zero to 80%,’€ explained Mahomed.

Of key importance is that trials amongst young children show good (60-80%) protection against severe widespread disease in children including TB meningitis (in the brain) and miliary TB (in the blood and other organs). BCG prevents around 40  000 cases of severe (disseminated) form of TB in young children globally.

‘€œAlthough BCG is, after polio, the most widely given vaccine in the world today, it therefore has limited effect of TB of the lungs in adults, the form of TB which is infectious and spreads TB in the community’€, Mahomed pointed out.

In South Africa more 95% of babies are routinely given the BCG vaccine at birth, based on World Health Organisation and South African recommendations.

Although BCG, a live attenuated vaccine, is generally very safe in most babies, the vaccine can rarely cause some serious side effects in a small number of HIV-infected babies (around 1%) if they are not started early on antiretroviral therapy (ART) to treat their HIV infection.

Professor Anneke Hesseling, Director of the Paediatric TB Research Program at the Desmond Tutu TB Centre at Stellenbosch University however said it was important to be ‘€œresponsible’€ with the data around the BCG vaccine or countries like South Africa could stand to lose the massive benefits of the vaccine.

She confirmed that the BCG was ‘€œvery effective’€ against the disseminated forms of TB and highly effective in preventing these more severe forms of TB, which may occur in around five to 10 percent of young children with TB.

‘€œThere are also other positive benefits of BCG vaccination. BCG access is a marker of access to healthcare and in many parts of the world it presents an opportunity to address other issues including access to general maternal and health care, access to other immunizations and nutritional support.

‘€œBCG is also used to treat bladder cancer in adults and has, in some studies, been shown to increase the protection against allergy, leprosy and all-cause (non-TB related) mortality in some countries. It is clear that BCG may do more to the immune system than just leading to some TB-protective immune responses,’€ Hassling added.

Addressing the concerns around administering a live vaccine to children with HIV, Hesseling said she and others believed the benefits outweighed the risks in settings with high burdens of HIV and TB such as South Africa.

‘€œIn developing countries like South Africa, babies born to HIV-infected mothers are given their BCG immunisation before we know their HIV status (which is usually only confirmed by around 6 weeks after birth). If the baby does become HIV positive there is a significant risk of BCG complications, but the most serious forms, disseminated BGC disease, is much reduced if HIV-infected babies are diagnosed early on and are treated rapidly with antiretroviral therapy.  

‘€œSince HAART has been routinely available to HIV-infected infants in the South African setting, we have seen very few of these serious vaccine compilations. Starting HAART early also reduces the risk of some less serious BCG complications such as BCG lymph glands which appear in the first months following the start of HAART, by more than 3-fold in HIV-infected babies. With the introduction of antiretrovirals to children at an earlier age we are seeing a dramatic decline in these BCG conditions, but importantly, also a massive reduction (more than 70%) in the risk of developing TB.

‘€œRather than demonising BCG we should focus our attention on preventing HIV infection in mothers and in newborns, and rapidly initiating those babies who are HIV-positive onto ARVs early,’€ said Hesseling.

‘€œThe take home message is that the problems presented by BCG in HIV babies, although not negligible, are very small compared to the bigger problems of better TB prevention in HIV-infected children ‘€“ where early ARVs and provision of Isoniazid (INH) prophylaxis after TB exposure can dramatically reduce TB rates These public health strategies are proven to be safe and effective and can greatly impact on TB control in settings like South Africa where we are faced with the twin pandemics of TB and HIV, also in children.’€