A vaccine first mass produced in 1924 to combat tuberculosis may offer protection against Covid-19, a study has found.
Academics studied countries that have high and low levels of the Bacillus Calmette-Guerin (BCG) jab and found a clear link between the vaccine and a lower death rate.
Detail on the vaccine’s popularity in certain countries was compared with each nation’s coronavirus outbreak — for both infections and deaths.
When differences in social, economic, and demographics were taken into account, scientists found that in places with a 10 per cent greater prevalence of the BCG vaccine there was also a 10.4 per cent reduction in COVID-19 mortality.
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The Bacillus Calmette-Guérin (BCG) vaccine (pictured) is used to fend off tuberculosis (TB) but it has long been known to have other health benefits, including helping a person’s immune system to fend off respiratory infections
The study, from academics at Virginia Polytechnic Institute and State University and the National Institutes of Health, has been peer-reviewed and published in the journal PNAS.
Writing in their paper, they say: ‘This epidemiological study assessed the global linkage between BCG vaccination and COVID-19 mortality.
‘Signals of BCG vaccination effect on COVID-19 mortality are influenced by social, economic, and demographic differences between countries.
‘After mitigating multiple confounding factors, several significant associations between BCG vaccination and reduced COVID-19 deaths were observed.’
Coronavirus have spikes on their surfaces which help them infect cells. The spike on SARS-CoV-2 (right), the virus causing the current pandemic, is very similar to the spike of a different coronavirus seen in bats (left). However, it is 1,000 times better at infecting human cells
WHAT IS THE BCG VACCINE?
BCG is currently given to around 130 million babies every year to protect them from TB.
It has the full name ‘Bacillus Calmette-Guérin’ and features a weakened version of the bacteria Mycobacterium bovis.
This microbe causes TB in animals such as cows and badgers.
When injected into people, the weak bacteria is attacked by the immune system.
The body then defeats the bacteria by producing antibodies.
These can then be rapidly produced and deployed if a person is infected by TB proper.
The BCG jab is thought to work in this way but also revs up the whole immune system so it’s more likely to snuff out any invading virus particles.
The NHS says the BCG jab can offer protection for up to 60 years – but scientists are unclear if adults who were already injected as children get any protection from the coronavirus because the evidence is lacking.
The BCG vaccine was invented a century ago and gives immunity to tuberculosis (TB) — a bacterial infection — but it is known to have other benefits.
Previous trials discovered people who receive the jab, which costs as little as £30, have improved immune systems and are able to protect themselves from infection.
For example, in a trial among Native Americans, BCG vaccination in childhood was able to offer protection against TB up to 60 years after vaccination.
These so-called off-target effects include enhanced protection against respiratory diseases, and have been recognised by the World Health Organization (WHO).
BCG has been used for more than 90 years but exactly how it works still remains a mystery.
And how it may protect against Covid-19 is an even larger enigma.
The best theory is that the vaccine, which contains a live bacteria called Mycobacterium, boosts the innate immune system, making it more effective.
Ongoing studies into whether BCG can help fend of COVID-19 are ongoing in Holland and Australia but, until these results are available, the researchers of the latest study say even transient immunity could help fight the pandemic.
‘[The BCG vaccine] may be useful in individuals at high risk, such as health workers, first responders, and police officers, or those with preexisting conditions such as obesity, diabetes, or cardiovascular disease,’ say researchers.
‘Similarly, even enhanced unspecific immunity through BCG vaccination in vulnerable age groups could ameliorate severe COVID-19.
‘Temporarily induced trained immunity could buy time until specific vaccines and/or effective treatments against SARS-CoV-2 infections become available.’
Commenting on the research, Professor Keith Neal, Emeritus Professor of the Epidemiology of Infectious Diseases at the University of Nottingham, said studies like this can be ‘problematical’.
‘Within the UK, most people over 30 and under 80 will have had BCG in the schools programme,’ he says.
‘Many children in the BAME groups will have continued to be vaccinated at birth, although people born outside the UK may not have been vaccinated.
‘Previous work on BCG suggests the age it is given impacts the affects it has on the immune system. The age of vaccination was not assessed in the paper.
‘There are also many different BCGs around the world. BCG has been shown to have a long duration of protective effect against TB.
‘Any BCG effect should be assessed in case control studies where mild, moderate and severe cases are included.
‘Further work is needed to assess the effect of BCG. There have been shortages of BCG vaccine so if confirmed this one for the planning of the next pandemic.’