A recent report claiming that the anti-tuberculosis (TB) vaccine, known as the BCG vaccine, protects against Covid-19 should be “interpreted with extreme caution”, according to a group of leading TB experts writing in the International Journal of Tuberculosis and Lung Disease. Authors of the new paper published on 28 April include leading South African researchers Dr Mark Cotton, Professor Simon Schaaf and Dr Anneke Hesseling.

“Unfortunately, as a consequence of [a study suggesting that BCG protects against death from Covid-19] some healthcare workers (and members of the general public) are now requesting revaccination as protection for themselves and vaccination of their non-BCG-vaccinated dependents, especially older children,” noted the authors.

While this is “understandable given the fear of Covid-19”, the use of “BCG for an unproven indication is irresponsible and may deplete BCG stocks for young children, for whom it has been proven to be a lifesaving preventive tool against TB-related morbidity and mortality”.

In many high-burden TB countries, BCG is routinely administered at birth to protect newborns from severe forms of TB such as TB meningitis.

In recent years, global BCG vaccine shortages (particularly in 2014 and 2017) have led to an upsurge in life-threatening cases of TB disease in infants.

“The risk associated with low vaccination coverage is highlighted by the dramatic increase in the incidence of TB meningitis in young children reported in association with BCG stock-outs,” noted the authors.

Controversial report

A recent report published on a popular preprint server (and which accordingly did not go through the normal peer review processes at respected scientific journals) suggested a correlation between low mortality rates from Covid-19 in countries that routinely deliver BCG vaccines at birth. The report has received very wide media coverage and has also been widely criticised by other scientists (see here, for example).

According to a statement issued by the International Union against Tuberculosis and Lung Disease, although “previous basic science research has shown some efficacy in BCG’s ability to boost the general immune system, the quality of the evidence has been criticised”. 

“Lacking was the gold standard of randomised clinical trials, where one group is given BCG and the other a placebo,” noted the Union.

Additionally, the authors of the new paper say there are a number of examples that go against this theory, particularly in the case of Germany – a country that has a relatively low death rate for Covid-19, yet does not include BCG in their childhood vaccination programme.

South Africa is one country that routinely administers BCG at birth.

“Several trials are planned to investigate whether BCG may indeed offer protection against Covid-19, including in healthcare workers,” noted the authors of the new paper. These include studies currently underway in the Netherlands, Australia and South Africa.

However, in the absence of any concrete evidence on whether or not BCG has any therapeutic action against Covid-19, the World Health Organisation has recently issued a scientific brief “calling for BCG to be used for neonatal BCG vaccination only in high-risk settings and not for the prevention of Covid-19”.

“Likewise, as the co-authors on this paper – who are pediatricians, public health experts and researchers with many years of experience in TB and BCG – we implore you to protect BCG supplies for young children, for whom the vaccine offers substantial proven benefits,” the authors wrote.

According to the Union, while “any rigorously performed intervention with a potential positive effect is welcome” – and the studies around BCG and Covid-19 “must be timely and well-resourced” – “at the same time, [they should] not divert BCG supplies from its original purpose of vaccinating young children against tuberculosis, which causes the most deaths of any infectious disease”.

The new paper noted that, ultimately, at present, “there is currently no compelling evidence, either for or against, that BCG protects individuals from Covid-19”.

“Outside of a clinical trial, healthcare workers (or other individuals) should therefore not receive BCG vaccination for protection against Covid-19.”

Most importantly, “fair allocation of scarce basic resources such as BCG is crucial, and it is an ethical imperative that the most vulnerable should receive the greatest benefit”, the authors concluded. DM/MC

This article was produced by Spotlight – health journalism in the public interest. Like what you’re reading? Sign up for our newsletter and stay informed.