Woman holding a baby

An old vaccine for new diseases?

Updated May 2023

The tuberculosis vaccine BCG may help protect against other allergies and infections, although not COVID according to the latest publications from a global project responding to the pandemic.

Long term trials suggest the Bacille Calmette-Guérin vaccine targeting tuberculosis improves the performance of the innate immune system in babies. This innate response is our first line of defence, at least in babies.

The study was expanded during the COVID-19 pandemic to see if BCG also offered protection against SARS-CoV2, in a collaboration between European researchers and Professor Nigel Curtis and his team at the Murdoch Children’s Research Institute in Melbourne.

“At the end of 2019 we thought that it would take at least two years to make a vaccine so we thought, while we’re waiting for these vaccines, we could at least try to protect healthcare workers on the front line by boosting their immune system,” says Professor Curtis.

“But within a few months, it became very obvious that Australia, with low infection rates, was exactly the worst place to be doing a COVID-related trial.

“With the support of the Gates Foundation, we rapidly expanded to Europe because at that stage, the COVID peak was in Italy and the UK.”

Using the methodology established in Australia, trial sites were set up in the UK, the Netherlands, Spain and, later, Brazil. In total there are over 35 sites with over 7,000 participants.

“The study has also allowed us to collect an enormous amount of data that allows us to understand, not just how BCG might work, but also a bit more about why some people get severe diseases and some don’t,” says Professor Curtis.

The team reported in April 2023 in the New England Journal of Medicine that that BCG does not protect against mild COVID-19, while the rapid arrival of COVID-19-specific vaccines meant they were unable to assess its usefulness in preventing severe disease or death.

Trials continue into assessing the role BCG could play in infants. “Babies who received BCG at birth compared with those who didn’t… had reduced rates of eczema,” says Professor Curtis.