Media reports have suggested countries that vaccinate their populations against tuberculosis (TB) using the BCG vaccine seem to have lower rates of deaths from COVID-19. Could the BCG vaccine reduce infections or deaths from the virus?

Clinical trials are underway, but at present, there is no good quality evidence that the BCG vaccination protects against COVID-19.

The UK, like most of Europe and the US, no longer routinely offers BCG vaccination to everyone because TB is not common in this country. BCG is used more widely in Asian and African countries where TB is still a problem. Some of these countries, despite being lower income than European countries, had lower COVID-19 reported cases and deaths.

The evidence at country level is interesting, but there are many problems with it. Countries are at different stages in the pandemic and have very different testing regimens. This variation could explain the differences in COVID-19 death rates.

The WHO and UK guidance continue to recommend the BCG vaccine for babies who are at higher risk of exposure to TB.

 

A story in the Metro newspaper highlighted research on BCG vaccination and death rates from COVID-19 that was conducted by the Johns Hopkins School of Public Health in the US. The media highlighted caution regarding the current level of evidence and said that “no final conclusions have been drawn.”

 

What is the basis for the claim?

The Johns Hopkins School of Public Health study is the most detailed study to date to have investigated the link between COVID-19 death rates and BCG vaccination. The study has not yet been peer-reviewed, meaning the final publication may change, though early reporting is common in the rapidly evolving field of COVID-19 research.

It looked at deaths from COVID-19 per million of population for the 50 countries reporting the most cases of coronavirus as of 29 March 2020. Typically, death rates for infectious disease – including those from respiratory infection – are lowest for high income countries and highest for low income countries. However, for COVID-19, the reverse was true. The median (average) COVID-19 mortality rate was 0.4 per million for low-middle income countries rising to 5.5 for high income countries.

The researchers adjusted their figures to take account of the country’s economy (Gross Domestic Product, GDP), the percentage of the population aged over 65 years, and the stage in the epidemic (the number of days since the 100th case had been reported). These are all factors that are expected to be associated with disease severity and mortality in a respiratory infection like COVID-19. They then looked at death rates for those countries that did and did not offer universal BCG vaccination. They found countries that used BCG vaccine had COVID-19 death rates 5.8 times lower than countries that did not use BCG vaccine.

However, this ecological research cannot account for differences in the level of testing and reporting by country, other confounding influences (such as the level of comorbidity and social distancing), or the rapidly evolving spread of the pandemic.

Overall considerable caution must be taken in attributing these findings to a direct protective effect of the BCG vaccine.

 

What do trusted sources say?

The WHO says it will evaluate the results of the BCG trials underway, which reportedly involve healthcare workers. However, at present is says there is: “no evidence that the Bacille Calmette-Guérin vaccine (BCG) protects people against infection with COVID-19 virus” and “WHO does not recommend BCG vaccination for the prevention of COVID-19.”

It warns that diverting supplies of the vaccine from countries where it is currently used risks outbreaks of TB in those areas, and says that those countries which use the vaccine to protect babies from TB should continue to do so.

Analysis by EIU Healthcare, supported by Reckitt Benckiser

 

Citation

  1. A Shet, D Ray et al. Differential COVID-19-attributable mortality and BCG vaccine use in countries. medRxiv preprint doi: https://doi.org/10.1101/2020.04.01.20049478. https://www.medrxiv.org/content/10.1101/2020.04.01.20049478v1.full.pdf (Accessed 21 April 2020)

 

Reading list

  1. Gursel, I. Gursel, Is Global BCG Vaccination Coverage Relevant To The Progression Of SARS-CoV-2 Pandemic?, Medical Hypotheses (2020), doi: https://doi.org/10.1016/j.mehy. 2020.109707
  2. World Health Organisation, Bacille Calmette-Guérin (BCG) vaccination and COVID-19 (scientific brief). https://www.who.int/news-room/commentaries/detail/bacille-calmette-gu%C3%A9rin-(bcg)-vaccination-and-covid-19 (Accessed 21 April 2020)
  3. Tuberculosis. NICE guideline NG33. Last updated 12 September 2019. https://www.nice.org.uk/guidance/ng33/chapter/recommendations#bcg-vaccination (Accessed 21 April 2020)