By Layal Liverpool
NIBSC/SCIENCE PHOTO LIBRARY
The BCG (Bacillus Calmette-Guérin) tuberculosis vaccine boosts the production of immune cells, which may explain why it can protect newborn babies from dying of sepsis.
Previous studies have shown that BCG vaccination can protect newborns against a broad range of infections beyond tuberculosis, reducing overall deaths from sepsis. But exactly how this works was unclear.
“Knowing the mechanism behind this effect will support the use of the BCG vaccine to prevent newborn sepsis,” says Nelly Amenyogbe at the Telethon Kids Institute in Perth, Australia. Amenyogbe and her colleagues analysed blood samples from 85 newborn babies in Gambia, Guinea-Bissau and Papua New Guinea, half of whom had been vaccinated.
Advertisement
They found that, three days later, the newborns who had been vaccinated had about twice as many immune cells, called neutrophils, in their blood.
In another experiment, the researchers vaccinated newborn mice with BCG and then infected them with bacteria to induce sepsis. They also infected non-vaccinated mice. Just like the human babies, the mice that had been vaccinated produced about double the number of neutrophils, which then protected them from dying by gobbling up the bacteria that cause sepsis.
“There is increasingly strong evidence that BCG, a vaccine designed to work against tuberculosis, has advantageous non-specific effects against a range of pathogens in humans,” says Danika Hill at the Babraham Institute in Cambridge, UK.
With this in mind, the BCG vaccine is currently being trialled in people as potential protection against covid-19. But “whether BCG, and any potential effect on neutrophils, could be beneficial against [the coronavirus] is unclear and warrants careful consideration”, says Hill.
Amenyogbe says BCG also has effects on other parts of the immune system, beyond neutrophils, and it is possible that these other effects may provide some benefit against covid-19.
“If vaccines such as BCG are able to provide non-specific protection against newly emerging pathogens, this could be a game changer for managing covid-19 and any future pandemics,” says Hill.
Journal reference: Science Translational Medicine, DOI: 10.1126/scitranslmed.aax4517
Sign up to our free Health Check newsletter for a monthly round-up of all the health and fitness news you need to know
More on these topics:
