Effect of BCG Vaccine on Covid-19

• 03 Apr 2020

Why in News

Recently, Doctors and scientists in India have expressed caution on a study, which argues that countries that have deployed the BCG-tuberculosis vaccine in their immunisation programmes have seen fewer deaths from COVID-19.

• BCG, or bacille Calmette-Guerin, is a vaccine for tuberculosis (TB) disease.

Key Points Related to Study

• BCG Vaccine Policy and COVID-19 Deaths
  
  • The middle and high-income countries
    
    • Countries that have universal BCG policy had 0.78 deaths per million people.
    • The countries that never had a universal BCG policy had a larger mortality rate, with 16.39 deaths per million people, a significant variation.
  • Low and middle-income countries, even if they had universal immunisation policies, were excluded from the analysis because they were also likely to have low testing rates for COVID-19 infection and therefore fewer reported deaths.
  • India having a universal BCG policy in place and relatively fewer deaths as a proportion of confirmed coronavirus infections, wasn’t included in the analysis.
• BCG Vaccine confers a strong immune response
  
  • The BCG vaccine is known to confer a strong immune response and a significant degree of protection against leprosy and non-invasive bladder cancers.
  • Those countries where the elderly were likely to have had a BCG shot in their childhood were likely to be better protected against coronavirus because COVID-19 was particularly lethal to the elderly.
• Cases of Different Countries
  
  • Japan (which has a BCG policy since 1947) had one of the early cases of COVID-19 but it has maintained a low mortality rate despite not implementing the most strict forms of social isolation.
    
    • Japan had 1,655 cases and 65 deaths as of March 29.
  • Iran, which has seen at least 3,000 deaths,began implementing its BCG vaccination policy only in 1984 and therefore anyone over 36 was vulnerable.
  • Spain, France, the United States, Italy and the Netherlands:
    
    • These countries don’t have universal BCG policies and have seen many deaths from COVID-19.
    • Many of these countries don’t have a universal programme because BCG has been shown to not be always protective against tuberculosis in adults as well as an increased risk of mycobacterium (bacteria) species.
    • Italy, where the COVID-19 mortality is very high, never implemented universal BCG vaccination.
• Views of Indian Scientists and Doctors
  
  • it is premature for India, that has had a consistent TB vaccination policy since 1968, to take comfort from the study.
  • Australia, the Netherlands, the United States are going to vaccinate healthcare workers with BCG. This may provide some evidence.

Source: TH