It's the plot of a hundred films: when things are at their worst some technology, long-neglected for flashier alternatives, saves the day. Scientists are hoping to make life imitate art by drawing on a last-ditch treatment for diphtheria and tetanus, and a very imperfect vaccine for tuberculosis (TB). Neither will magically cleanse the world of the current plague in a Hollywood-friendly ending, but either or both may save a lot of lives before an effective vaccine is available.
The BCG vaccine doesn't quite fit the role of having been neglected for decades; it is given to millions in regions where TB remains a major killer. BCG is safe and very cheap, but where more modern vaccines provide close to 100 percent protection against lethal diseases, BCG's effectiveness is much lower with estimates of 50-80 percent in different studies. With TB killing 1.5 million children a year, doctors in affected countries are desperate for something better.
However, where most vaccines work only against a specific virus or bacterium, BCG stimulates the immune system more broadly. Introduced in 1921 for TB, it is now recognized as also being beneficial against leprosy and Buruli ulcers. A growing body of research indicates it can help protect against pathogens completely unrelated to TB, and even some preliminary understanding of how it achieves this remarkable feat.
Danish researchers have published evidence BCG provides an average of 30 percent protection for months after vaccination against every type of infection they have tested it against.
Science reports teams in the Netherlands and Australia are about to begin trials giving healthcare workers who are likely to be exposed to the new coronavirus either BCG or a placebo. If effective, the vaccine may dampen the seriousness of an infection, rather than stopping it outright, so the studies will measure success by days taken off work, rather than the numbers testing positive to COVID-19.
No one thinks it will be a complete solution, but BCG's safety (except in pregnancy) is already established, so we'll have results from both trials long before any corona-specific vaccine is available. BCG could be the equivalent of going into battle with 30 percent effective armor – not ideal, but better than nothing.
Many doctors around the world are reaching back even further, to a technique developed in the 1890s to provide short-term protection during epidemics.
As our bodies learn to fight off an infection they produce antibodies, and we know that for most COVID-19 survivors these come in abundance. Why not, 19th-century doctors thought, take blood from those now immune to a disease and give it to those still vulnerable? As Professor Arturo Casadevall of Johns Hopkins University points out in the Journal of Clinical Investigation this provided the best method of treating many diseases for 50 years and, bolstered with modern purification technologies probably saved lives in the 2013 Ebola epidemic.
During the original 2003 SARS outbreak, a small group of patients given antibodies from others appeared to do better than their counterparts, particularly when they received them early on. The paper also notes that, for unknown reasons, antibody therapy has proven more effective in protecting infected people whose symptoms are yet to appear. This protection is probably short-term, but could be immensely precious to those thought to have been exposed to the virus but not yet sick.
"Deployment of this option requires no research or development," Casadevall said in a statement. "It could be deployed within a couple of weeks since it relies on standard blood-banking practices."