The World Health Organisation on Monday played down studies suggesting that the Bacille Calmette-Guerin vaccine may be effective in the prevention of the highly contagious coronavirus infection.
Photograph: Dado Ruvic/Illustration/Reuters
BCG vaccination prevents severe forms of tuberculosis in children and diversion of local supplies may result in neonates not being vaccinated, resulting in an increase of disease and deaths from tuberculosis.
In its daily situation report, the WHO said there is no evidence that the BCG vaccine protects people against COVID-19.
"There is experimental evidence from both animal and human studies that the BCG vaccine has non-specific effects on the immune system. These effects have not been well characterised and their clinical relevance is unknown," the report said.
On April 11, the WHO updated its ongoing evidence review of the major scientific databases and clinical trial repositories, using English, French and Chinese search terms for COVID-19, coronavirus, SARS-CoV-2, and BCG.
The review yielded three preprints wherein the authors compared the incidence of COVID-19 cases in countries where the BCG vaccine is used with countries where it is not used and observed that countries that routinely used the vaccine in neonates had less reported cases of COVID-19 to date.
"Such ecological studies are prone to significant bias from many confounders, including differences in national demographics and disease burden, testing rates for COVID-19 virus infections, and the stage of the pandemic in each country," it said in the report.
Two clinical trials addressing this question are underway, and the evidence will be evaluated when it is available, the WHO stated.
Therefore, the global body said it continues to recommend neonatal BCG vaccination in countries or settings with a high incidence of tuberculosis.
Confirmed cases of the novel coronavirus around the world have surpassed 2 million, the US-based Johns Hopkins University. According to its data, 2,019,320 people have been diagnosed with the coronavirus globally. Some 119,483 people have died of the disease caused by this virus.
