Scientists do the best they can, but no drug is properly tested until it is fully deployed. And sometimes the result is better than anyone could have hoped.
In all the hand-wringing over whether it was right to release untested drugs to treat ebola victims, an important truth has gone largely unreported: even when completed, drug trials rarely tell the whole story. Many drugs have side effects that emerge only after deployment in the population at large. If you want proof, look at the millions of reports of adverse effects on the US Food and Drug Administration’s new OpenFDA website.
It’s worth noting, however, that unexpected effects can sometimes be surprisingly good. Take BCG. The Bacillus Calmette-Guérin vaccination was designed to protect against tuberculosis but it does far more. It stimulates an immune reaction against bladder cancer, for instance – the vaccine, delivered directly into the bladder, is now a standard treatment for this disease. It has also been used to fight multiple sclerosis and diabetes. No one knows exactly why this immunity-boosting effect takes place.
Other vaccines also have unexpected protective effects. Studies have shown that, when deployed in Africa, the measles vaccine cuts deaths from diseases other than measles by a third. The way it stimulates the immune system seems to enhance the body’s defence against infections. As a result, pneumonia, sepsis and diarrhoea – the most common causes of death in developing countries – are reduced by vaccinating against a completely unrelated disease.
We have known this for a while. In the early 20th century a physician logged the survival rates of children when vaccination was introduced to Sweden. Even though tuberculosis mostly kills older children, the vaccination had an effect on babies, too: those who had received it stood a much higher chance of reaching their first birthday. Follow-up trials in the US and UK in the 1940s and 1950s suggested that BCG-vaccinated children had a 25 per cent lower death rate from diseases unconnected to tuberculosis.
More recent studies have shown that vaccines for both smallpox and BCG can reduce susceptibility to lymphoma, leukaemia and asthma. Some researchers suggest that the rise in allergies and asthma in developed countries might be linked to the phasing out of the BCG vaccines.
There are still improvements to be made. This year, the World Health Organisation (WHO) has announced that it is looking into tweaking the sequence in which certain vaccines are administered in developing countries, after a team of experts concluded that the way they interact might be having an adverse effect on girls’ health.
It is not the first time that gender-specific effects have been noted after vaccination. In 1992, WHO withdrew a high-dose measles vaccine that had been shown to increase girls’ susceptibility to infection. No one is advocating that we drop any vaccinations – they save far more lives than they put at risk. But just changing the order in which they are given might help them save even more lives.
In the messy world of pharmaceuticals, nothing is ever certain. Whatever the outcome, releasing the untested ebola drugs was the right thing to do. In a crisis, we sometimes have to jump and hope for the best. Or maybe even better.