Why are there effective vaccines against COVID-19 but not TB?
Several vaccines against COVID-19 have been shown to be highly efficacious and seem close to licensure — a development made in less than 1 year.
Yet, after 140 years, there is still not a widely used, highly effective vaccine against tuberculosis. We asked Aaron E. Glatt, MD, MACP, FIDSA, FSHEA, chairman of the department of medicine and chief of infectious diseases at Mount Sinai South Nassau in New York and professor of medicine at Icahn School of Medicine at Mount Sinai, why.
When people think of TB, they do not think of it as a vaccine-preventable disease. However, a vaccine for TB named after the French scientists who developed it, Calmette and Guérin, does exist. It is not recommended for use in the United States to prevent TB; however, in many other parts of the world, especially in other countries where TB is very prevalent, it is routinely used with varying success in young children to prevent their acquisition of TB.
With the rapid advances we have seen in the development of a vaccine against COVID-19, a disease entity that is still not 1 year old, one might wonder why we have not been successful in developing a better vaccine against TB. The question is further magnified when you consider that there are well over 1 billion people worldwide with latent TB infection. Some estimates suggest that one in four people worldwide have latent TB, which begs the question, “Why has a successful vaccine not been found?”
The answer is simple — vaccines are not easy to develop, despite the many success stories we have to date. Many diseases such as TB, malaria, Staphylococcus aureus — all major world pathogens — have not seen success in terms of vaccine development, certainly not because of lack of effort. We have had a relative modicum of success with influenza, but it remains elusive in finding a great vaccine therapy. Yet other illnesses, such as many of the childhood viral exanthems, have been almost totally eradicated — think polio or measles.
Each infectious agent is different. Some mutate easily, thwarting vaccine efforts, whereas others simply pose technical issues, making an effective vaccine near impossible.
However, there is renewed hope based on some of the COVID-19 efforts. New vaccine modalities such as messenger RNA vaccines potentially open up an entire new vast technology for vaccine development. Maybe the silver lining in this horrific COVID-19 pandemic will be the development of a prevention for TB.
Click here to read the Cover Story, 'In shadow of COVID-19, TB vaccine research enters new era.'