TB vaccine failing worldwide
Aug 23, 2005
GLOBAL health scientists are back in the laboratories after the tuberculosis (TB) vaccine appears to be having little success. The vaccine is expected to protect children from contracting the disease later in life.
By Denis Ocwich
GLOBAL health scientists are back in the laboratories after the tuberculosis (TB) vaccine appears to be having little success. The vaccine is expected to protect children from contracting the disease later in life.
The BCG vaccine, (named after French researchers Albert Calmette and Camille Guerin), was first tested in 1921.
It works by exposing the body to a very small, but harmless amount of the agent that causes the disease, so the body can learn to attack it and prevent future infection. It is approved by the World Health Organisation (WHO) and used regularly in almost all countries.
In Uganda, it was nationalised in 1983. Children are given single jabs on shoulders, when they are a few days or weeks old. All children born in the country are supposed to be vaccinated free of charge.
Despite the vaccine, the rate of infection and resistance to treatment, both in adults and children, has widened. It is even worse in children, who succumb much easily to TB. Uganda is now on the list of the top 22 ‘high burden’ countries, which contribute 80% to the global caseload. The Global Tuberculosis Control Report Card 2005 ranks Uganda among the 12 countries, where less than a half of TB cases are being cured. The report urges the above countries to “make TB control a greater priority†to avoid thousands of needless deaths.
Dr. Issa Makumbi, the assistant commissioner of Health services in-charge of immunisation says the failure of the vaccine is partly due to HIV/AIDS, which weakens the body immunity, making it susceptible to diseases. HIV wakes up all sleeping dogs, including latent TB to explode. Some babies get the disease from infected parents. Others develop it when they are adults. But many acquire it through inhalation of air contaminated by the germ coughed out, sneezed, spitted, or propelled through speaking to an infected person. Between 70,000 and 80,000 people are infected every year in Uganda. Of these, only about a half access treatment and a few get healed. About 25,000 people are reported to have died of TB between 2000 and 2003.
“Four years ago, four (40%) out of every 10 Ugandans with TB were being cured using the direct oral treatment strategy. Now, only three (30%) out of 10 are being cured,†health minister Jim Muhwezi said during this year’s world TB Day in March.
TB treatment takes between six and eight months of swallowing tablets, normally under close medical supervision in the first two months. The common drugs are isoniazid and rifampicin.
However, HIV is not the only excuse. Early this month, the BBC reported that the TB vaccine is failing in countries around the Equator, in Africa, Asia and Latin America because people there “have another simultaneous mechanism that acts in a subversive role to undermine the effects of the protective mechanism,†London University team wrote in Nature Review Immunology.
This subversive mechanism allows TB to evade destruction of the immune system and thrive in parts of the body such as the lungs. The BCG vaccine works well in other parts of the body, but fails to destroy the TB germs in the lungs.
World scientists are now trying to make another vaccine that can attack from all angles of the body, especially the lungs.
“We will have to carry out more trials to see if the new vaccine actually stops people from contracting TB, but initial results show that MVA85A works perfectly well alongside BCG. It is safe and stimulates a strong immune system,†says Dr. Helen McShane from Oxford University’s Centre for Clinical Vaccinology and Tropical Medicine.
McShane, who led a team of researchers on the yet-to-be-approved MVA85A vaccine, says it might be given to babies six months after birth or in adolescence, when the effect of BCG begins to wane. The current BCG vaccine works well to protect children from the most severe childhood form of TB. But when the kid reaches five years, it loses strength.
“In the next five to 10 years, hopefully, the (combination) vaccine against TB, malaria and HIV/AIDS will be in place,†says Makumbi.
Makumbi, however, says without immunisation, the TB situation in the country would be worse. And until another vaccine is approved, children will have to continue receiving BCG vaccines until a new vaccine is approved by WHO.
Ends
GLOBAL health scientists are back in the laboratories after the tuberculosis (TB) vaccine appears to be having little success. The vaccine is expected to protect children from contracting the disease later in life.
The BCG vaccine, (named after French researchers Albert Calmette and Camille Guerin), was first tested in 1921.
It works by exposing the body to a very small, but harmless amount of the agent that causes the disease, so the body can learn to attack it and prevent future infection. It is approved by the World Health Organisation (WHO) and used regularly in almost all countries.
In Uganda, it was nationalised in 1983. Children are given single jabs on shoulders, when they are a few days or weeks old. All children born in the country are supposed to be vaccinated free of charge.
Despite the vaccine, the rate of infection and resistance to treatment, both in adults and children, has widened. It is even worse in children, who succumb much easily to TB. Uganda is now on the list of the top 22 ‘high burden’ countries, which contribute 80% to the global caseload. The Global Tuberculosis Control Report Card 2005 ranks Uganda among the 12 countries, where less than a half of TB cases are being cured. The report urges the above countries to “make TB control a greater priority†to avoid thousands of needless deaths.
Dr. Issa Makumbi, the assistant commissioner of Health services in-charge of immunisation says the failure of the vaccine is partly due to HIV/AIDS, which weakens the body immunity, making it susceptible to diseases. HIV wakes up all sleeping dogs, including latent TB to explode. Some babies get the disease from infected parents. Others develop it when they are adults. But many acquire it through inhalation of air contaminated by the germ coughed out, sneezed, spitted, or propelled through speaking to an infected person. Between 70,000 and 80,000 people are infected every year in Uganda. Of these, only about a half access treatment and a few get healed. About 25,000 people are reported to have died of TB between 2000 and 2003.
“Four years ago, four (40%) out of every 10 Ugandans with TB were being cured using the direct oral treatment strategy. Now, only three (30%) out of 10 are being cured,†health minister Jim Muhwezi said during this year’s world TB Day in March.
TB treatment takes between six and eight months of swallowing tablets, normally under close medical supervision in the first two months. The common drugs are isoniazid and rifampicin.
However, HIV is not the only excuse. Early this month, the BBC reported that the TB vaccine is failing in countries around the Equator, in Africa, Asia and Latin America because people there “have another simultaneous mechanism that acts in a subversive role to undermine the effects of the protective mechanism,†London University team wrote in Nature Review Immunology.
This subversive mechanism allows TB to evade destruction of the immune system and thrive in parts of the body such as the lungs. The BCG vaccine works well in other parts of the body, but fails to destroy the TB germs in the lungs.
World scientists are now trying to make another vaccine that can attack from all angles of the body, especially the lungs.
“We will have to carry out more trials to see if the new vaccine actually stops people from contracting TB, but initial results show that MVA85A works perfectly well alongside BCG. It is safe and stimulates a strong immune system,†says Dr. Helen McShane from Oxford University’s Centre for Clinical Vaccinology and Tropical Medicine.
McShane, who led a team of researchers on the yet-to-be-approved MVA85A vaccine, says it might be given to babies six months after birth or in adolescence, when the effect of BCG begins to wane. The current BCG vaccine works well to protect children from the most severe childhood form of TB. But when the kid reaches five years, it loses strength.
“In the next five to 10 years, hopefully, the (combination) vaccine against TB, malaria and HIV/AIDS will be in place,†says Makumbi.
Makumbi, however, says without immunisation, the TB situation in the country would be worse. And until another vaccine is approved, children will have to continue receiving BCG vaccines until a new vaccine is approved by WHO.
Ends