TB vaccine could help treat COVID

If you were born before the 1990s the chances are you got a routine BCG vaccination at school. This is used to protect against the bacteria that cause tuberculosis or TB. But recently scientists have spotted a pattern connecting countries with BCG vaccination programmes that repeatedly vaccinate people throughout life and lower rates of Covid-19, suggesting that BCG vaccines, especially in older people, might be protective against the complications of catching the new coronavirus. If that's true, while we wait for a covid vaccine, perhaps we could use the BCG to protect people instead? On the other hand, it could just be a spurious association, and that's what a large trial looking at healthcare workers across several countries is now setting out to discover. Chris Smith spoke with John Campbell, who is at the University of Exeter…

John: These papers that have come out over the last few months have been very important. There's now three of them, at least, that have looked at whether BCG is associated with COVID rates. And in fact, it does look as though there is an association with countries who have high BCG coverage tending to have lower problems with COVID. There is evidence that BCG may have important effects on the immune system acting as a sort of booster to the immune system generally.

Chris - It's not just the simple fact that if you have a country that's rich enough to have a vaccination program, and you compare that with a poor country that doesn't have a vaccination program, you're merely reflecting the richness of the country and its ability to cope with any kind of pressure, and it's not the BCG that's doing it per se?

John - Absolutely. And that's one of the confounding factors that have to be considered in these types of studies. And that's really the reason that the studies that are going to give a definitive answer are going to be based on individual large randomized trials. And that of course is what we are doing. We in the UK are part of a large international research effort led from Melbourne in Australia. And what we are doing is testing BCG compared to a dummy vaccination in 10,000 healthcare workers and following them up for a whole year. And what we're looking at is whether BCG might stop people getting COVID or if they do get COVID, whether it might result in reduced severity of the disease.

Chris - And you'd anticipate that the reason that older people appear to be more vulnerable when they catch COVID, at least one factor might be that any immunity they may have had to BCG administered previously has now worn off with age and therefore they become more susceptible?

John - Yeah. And that's an important observation because a number of countries still have repeat programs of vaccination using BCG. So there's at least 16 countries listed by the WHO, but many people will probably have waning immunity. So what we're doing can probably thought of as a sort of general booster to the immune system

Chris - Is your trial not then going for the wrong group of people because by looking at healthy fit hale and hearty healthcare workers, are we possibly missing a trick? Should you not be going in and hitting older people who are at higher risk because then the effect or impact if there is one would be easier to spot, it would be magnified?

John - There's a strong argument for giving it to older people that is certainly true, but healthcare workers are at the sharp end and we felt that, you know, where we can do something to protect healthcare systems and healthcare workers - that's an important group. And in the UK in particular, we are focusing not just on healthcare workers, but on care home staff who are a particularly vulnerable group of individuals. We think that targeting care home staff and community based healthcare workers is really good because it's very important the healthcare system is also supported.

Chris - It'll be ironic, won't it, if your results show that we've got something already in our medicine chest that we could use against this and we don't need to wait for a vaccine.

John - Yeah. This is the really exciting thing about this study because not only the sort of premise for this study is that the BCG vaccine gives these nonspecific effects, including important effects against viruses - a number of viruses, RSV the respiratory syncytial virus, the flu virus, and some, corona-type viruses, there's good evidence that we may be on to something here - it's been given to 4 billion people. It's safe and it's widely available. It would be fantastic if we found that it could buy us the time whilst the specific vaccines come through.

Chris - And in terms of scale, how much of a difference can BCG make to a person's COVID outcome?

John - The work that has recently been published from Greece within the last couple of months, the so called activate trial, identified that people - older people - who had been given BCG had a really quite remarkable reduction in upper respiratory viral type infections. In fact, it actually reduced by 79% compared to people who had been given a placebo. If we were even remotely near that, it would be absolutely fantastic.