TB Vaccines Could Spread Infection
TB vaccinations could actually spread the lung infection by clearing the way for tougher strains to flourish, a new study has claimed.
Vaccinating against tuberculosis might simply remove a weak form of the infection, allowing a virulent strain to break out, researchers from the University of Bristol found.
Nearly nine million new cases of TB break out every year, with nearly two million deaths worldwide. Efforts to create a vaccine have created more than 200 candidates, many of which are currently undergoing animal testing and early clinical trials.
Large-scale genetic analysis of strains of TB mycobacteria have shown they are more varied than first thought and that vaccines may be effective against only some of the circulating strains.
Dr Caroline Colijn, from Bristol’s department of engineering and maths, devised several models to replicate how these various strains would react to certain drugs.
She said: “In most scenarios increasing vaccine coverage reduces the overall TB burden. However, the benefits are reduced if the preferential removal of one strain allows a previously suppressed strain to succeed.
“We found that there is a possibility that TB prevalence may increase due to a vaccination programme effective against a dominant strain, if that strain didn’t provoke a good immune response.”
Source: Nursing In Practice, 10th October 2008.
Vaccine Could Give Deadly Form of TB to HIV Positive Babies
The World Health Organization says a study has shown that babies with HIV could die if given a standard tuberculosis vaccine.
WHO says a three-year study in South Africa found babies born with HIV had a higher risk of contracting a deadly form of TB if given the widely used BCG vaccine.
The study recommends not vaccinating babies with HIV and delaying vaccination for those babies whose HIV status is unknown.
The study was published Wednesday in the journal Bulletin of the World Health Organization.
Source: The Associated Press, 1st July 2009.
BCG Vaccine is NOT Protective Against TB
A new tuberculosis vaccine is urgently needed.
These results demonstrated that neonatal BCG immunization followed by DNAhsp65 boosters is highly immunogenic but is not protective against tuberculosis.
Source: Scandinavian Journal of Immunology, Volume 71 Issue 2, Pages 63 – 69, 30 November 2009.
Tuberculous meningitis in Bacille Calmette-Guerin-vaccinated children: clinical spectrum and outcome
The Bacille Calmette-Guérin vaccination (BCG) contributed widely to reduce tuberculosis incidence in developing countries. The aim of this report was to assess the clinical “spectrum” and outcome of tuberculous meningitis in 16 Bacille Calmette-Guérin-vaccinated Tunisian children. They were 9 boys and 7 girls aged 2 to 168 months (median 72 months ± 65.88). Patients presented mainly with nonspecific symptoms. Neurologic severity was classified as grade I (n = 6) and grade II or III (n = 10). At short-term course, the majority of patients developed serious complications: hydrocephalus (n = 12), seizures (n = 8), tuberculoma (n = 6), and acute respiratory failure (n = 2). Three patients died. Among survivors, 4 patients showed a complete recovery while 9 developed permanent sequelae which were mild (n = 6) to severe (n = 3). Despite the Bacille Calmette-Guérin vaccination, tuberculous meningitis remains a life-threatening condition; vaccinated children have shown common presentation of tuberculous meningitis in terms of severity and poor outcome.
Source: J Child Neurol. 2012 Jun;27(6):741-6. doi: 10.1177/0883073811426930. Epub 2011 Dec 21.