TUBERCULOSIS: History: June 18: 90 Years of Tuberculosis Vaccination

June 16, 2011 by Project Staff
National Library of MedicineJune 18, 2011, marks an important anniversary in the history of infectious disease and vaccines—on June 18, 1921, the tuberculosis vaccine was first given to a human. The vaccine, developed by French scientists Albert Calmette and Camille Guérin, was an oral preparation of Bacillus Calmette-Guérin, or BCG in shorthand. BCG is a weakened form of a tuberculosis bacterium that causes the disease in cows. Benjamin Weill-Hall (1875-1958), French pediatrician and bacteriologist, fed the vaccine to infants in Paris who were at risk for the disease in this first use of the vaccine.



Albert Calmette (1863-1933) had acquired the Mycobacterium bovis strain of tuberculosis, which had been isolated from the milk of an infected cow, in 1904. In 1908, at the Institut Pasteur in Lille, France, he and veterinarian Jean-Marie Camille Guérin (1872-1961) began attenuating M. bovis by passing it through a growth medium they had developed specifically for this purpose. Their immediate goal was to weaken the bacteria to the point where they could no longer kill a guinea pig. In the end, the researchers hoped to produce an attenuated strain of the bacillus that would safely confer immunity to an uninfected human host. It would be 13 years before they saw the fruits of their efforts.

The League of Nations endorsed the oral BCG vaccine in 1928. Intradermal (injected) BCG vaccine began to be used in 1927; this became the most common mode of delivery of the vaccine. Today, BCG vaccine is not routinely used in the United States, but is given to about 100 million children worldwide each year. The vaccine does not prevent primary tuberculosis infection (though it does protect children from certain severe forms of tuberculosis). As the World Health Organization says in its position paper on tuberculosis vaccine, “Despite its shortcomings, BCG vaccination is considered a life-saving and important part of standard TB control measures in most endemic countries.”

More than 9.4 million new cases of tuberculosis are diagnosed each year, and one in three individuals worldwide is infected. An estimated 1.7 million people died from tuberculosis in 2009. Thus the need for new, more effective TB vaccines is clear, and many groups are working toward this goal. One of the concepts being studied is a so-called prime-boost regimen, in which one vaccine is given to ready the immune system to recognize TB and another vaccine follows that stimulates the body’s memory immune cells. (This approach has been applied to HIV vaccines and resulted in encouraging results in one large-scale trial.) The Aeras Global TB Vaccine Foundation, a nonprofit organization devoted to TB prevention, is one of the leading groups in developing and testing TB vaccines.

Further Information
See the tuberculosis entries in our collected disease timeline, and read about a global TB vaccination effort in the wake of World War Two in this blog post.
Sources
Aeras Global TB Foundation. Vaccine Science: TB Vaccine. http://www.aeras.org/about-tb/vaccine-science.php
Plotkin SA, Orenstein WA, Offit PA. Vaccines, 5th ed. Philadelphia: Saunders, 2008.
World Health Organization. Vaccine Position Papers: BCG. http://www.who.int/wer/2004/en/wer7904.pdf
World Health Organization. Tuberculosis. http://www.who.int/mediacentre/factsheets/fs104/en/
http://www.historyofvaccines.org/content/blog/june-18-90-years-tuberculosis-vaccination

TUBERCULOSIS: Simple Face Masks Could Significantly Prevent Spread of TB to Non-Infected Patients

Face masks worn by patients infected with tuberculosis (TB) may be able to significantly cut transmission rates to non-infected patients, according to a new study by researchers from the U.S. and South Africa. The study was conducted in a specialized airborne infections research facility in South Africa, which was designed to allow study of methods to control the spread of TB. Transmission rates were measured using healthy guinea pigs exposed to infected patients. The results of the study will be presented at the ATS 2011 International Conference in Denver.
“We found that when infectious patients with multidrug resistant tuberculosis (MDR-TB) wore face masks while they were hospitalized, the face masks helped decrease the transmission of tuberculosis by 50 percent compared to when the patients did not wear face masks,” says study author Ashwin Dharmadhikari, MD, associate physician at Harvard Medical School’s Brigham &Women’s Hospital. “Simply put, face masks were able to cut tuberculosis transmission in half.”
The masks may represent a simple way to reduce TB transmissions in areas with limited resources and widespread TB. “This is especially important when one thinks about the importance of protecting healthcare workers and other patients from getting TB when these vulnerable individuals might be in the same room as a TB patient,” says Dharmadhikari.
During the three-month study period, a series of 17 adult TB patients occupied the Airborne Infections Research Facility ward at the Mpumalanga Provincial MDR-TB Referral Hospital in Emalahleni, South Africa. Each patient occupied the ward for three weeks before being replaced and was encouraged and monitored to make sure face masks were worn for 12-hour periods on alternate days. Masks were removed during mealtimes and to allow patients to take medications.
A mechanical ventilation system exhausted all ward air on alternating days to each of two identical exposure chambers holding 180 healthy guinea pigs equally divided into an intervention group and a control group. Skin tests to monitor for tuberculosis infection were administered to the guinea pigs at the beginning of the study and monthly during the study. Intervention group animals only breathed ward air during periods when patients wore surgical face masks, and control animals only breathed ward air during periods when patients did not wear any masks. At the end of the study, efficacy was determined by comparing the incidence of infection among animals in each chamber.
Guinea pigs in the control group had more than twice the risk of becoming infected compared to guinea pigs in the intervention group. In the control group, 69 animals (76 percent) became infected. In the intervention group, 36 animals (40 percent) became infected.
“These findings provide evidence on methods that could be used for TB control,” Dharmadhikari says. “They may also help healthcare facilities and other stakeholders involved in TB control decide on how suitable this intervention is for protecting individuals against TB infection in the environments in which they work.”
In a traditional clinical setting, the efficacy of face mask use will depend in part on the ability of the patient to keep the mask on, Dharmadhikari notes.
“In the current study, patients wore the masks for 12-hour periods on alternate days, which may be difficult to achieve in actual inpatient clinical settings,” he said. “However, mask usage for shorter periods of time, such as when patients with chronic cough or other symptoms suggestive of TB present to a clinic or hospital for evaluation, may be more easily achievable and still provide reduction in transmission,” he adds.
“In those settings, it may be possible to encourage patients to wear masks while they are getting worked up for TB, so that the chances of healthcare workers or other patients getting TB are reduced,” he says.
Dharmadhikari says additional studies are needed to determine how well face mask use is accepted by patients, healthcare workers and health systems, how masks contribute to a hospital’s infection control program, and whether masks are economically and logistically feasible interventions in settings with a high burden of TB.
“It is important to keep in mind that masks should be viewed as part of a comprehensive TB infection control program that also includes timely diagnosis of TB patients and initiation of effective treatment,” he notes. “While masks worn by patients helped reduce TB transmission, they likely best fit into a plan that includes additional methods of TB infection control.”
http://www.infectioncontroltoday.com/news/2011/05/simple-face-masks-could-significantly-prevent-spread-of-tb-to-non-infected-patients.aspx