tb-vaccine-as-anti-covid-candidate-summary

Context: In a growing list of global trials on the efficacy of tuberculosis vaccines in preventing Covid-19, one is an upcoming trial being conducted by the Indian Council of Medical Research (ICMR) on the BCG vaccine.

What is the BCG vaccine?

  • According to the US Centres for Disease Control and Prevention, BCG (or Bacillus Calmette-Guerin) is  given between six months after the birth of a child to prevent tuberculosis meningitis and miliary disease. BCG is used in many countries with a high prevalence of Tuberculosis(TB).
  • BCG is a vaccine that uses a live attenuated strain (potency of the pathogen artificially disabled, but identifying characters retained) derived from an isolate of Mycobacterium Bovis. 
  • India, like many other Asian, African, and Latin American countries, has a current national BCG vaccination policy for all at birth. 
  • Countries that have terminated their policies or only recommend the vaccine for specific groups are mostly in Europe and North America.
  • In India:
    • The vaccine was first used in the world in 1920 and first introduced in India as a pilot project in the year 1948
    • In 1949, it was started in schools across the country. In 1962, the National TB Program started in India and children were vaccinated soon after birth across the country. 
    • According to the National Family Health Survey, 91.9 percent of children between the ages of 12 and 23 months have received the vaccine. 
    • Outside of some Northeastern states, almost all states have above a 90?G vaccination rate. 
    • According to the National Health Profile, India has a production capacity of 2,800 lakh BCG vaccine doses.

ICMR’s upcoming study on BCG:

  • It will focus on the vaccine’s potential in reducing the chance of Covid-19 death among those who are above age 60. According to ICMR, with new finalised details of this study, results could be expected soon.
  • The study will be conducted in conjunction with the National Institute for Research in Tuberculosis.
  • Earlier, ICMR had said that it would not recommend the BCG vaccine until “definitive results” from the study showed possible anti-Covid immunity. 
  • Outside of ICMR’s studies, institutional-level trials in different parts of the country are also assessing the potential.

Other ICMR studies:

  • One study seeks to assess the incidence of Covid-19 amongst healthcare workers who were taking the antimalarial drug hydroxychloroquine (HCQ) as well as any side effects from the drug’s use. 
    • The Covid-19 National Taskforce had recommended the use of HCQ as a prophylaxis (protective and preventative) against Covid-19 infection for asymptomatic healthcare workers and asymptomatic household contacts of positive cases.
  • Also, ICMR has been accepting applications nationwide to study the effectiveness of plasma therapy, which injects antibodies from a recovered patient into a severely ill patient.

What is known about BCG’s action in Covid patients?

Earlier studies shows following link between BCG and COVID in countries having BCG-tuberculosis vaccine in their immunisation programmes:

  • Countries having BCG universal policy: 55 middle and high-income countries chosen for the analysis that have a current universal BCG policy had 0.78 deaths per million people.
  • Countries that never had a BCG policy: Whereas middle and high income countries that never had a universal BCG policy (5 countries) had a larger mortality rate, with 16.39 deaths per million people.
  • Significant variations in the studies:
  • Low and middle-income countries were excluded, even if they had universal immunisation policies because they were also likely to have low testing rates for COVID-19 infection and therefore fewer reported deaths. 
  • India excluded, while having a universal BCG policy in place and relatively fewer deaths as a proportion of confirmed coronavirus infections. 
    • Many experts say that India tests relatively too little. Hence it is too early for India (that has had a consistent TB vaccination policy since 1968 ) to take comfort from the study.
  • Case of Italy and Japan: 
    • Italy, where the COVID-19 mortality is very high, never implemented universal BCG vaccination. 
    • On the other hand, Japan (and 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.
  • Also Iran, which has seen at least 3,000 deaths and has a BCG vaccination policy, only began implementing it in 1984 and therefore anyone over 36 was vulnerable. 
  • Spain, France, the United States and the Netherlands don’t have universal BCG policies and have seen many deaths from COVID-19. 

Notwithstanding the above findings, the link to BCG and COVID-19 from these studies is intriguing. A possible explanation is that children who have been vaccinated with BCG are less susceptible to infection with SARS-CoV-2 and so there is less spread of the virus to older populations, although this would need to be demonstrated.

 

Universal Immunization Programme (UIP)




 
  • Launched by the Ministry of Health and Family Welfare, Government of India in 1985, UIP prevents mortality and morbidity in children and pregnant women against 12 vaccine preventable diseases.
  • Under UIP free of cost vaccination is provided against twelve vaccine preventable diseases i.e. Tuberculosis, Diphtheria, Pertussis, Tetanus, Polio, Hepatitis B, Pneumonia and Meningitis due to Haemophilus Influenzae type b (Hib), Measles, Rubella, Japanese Encephalitis (JE) and Rotavirus diarrhoea.

Mission Indradhanush

  • In order to give maximum protection to the children against Vaccine Preventable Diseases (VPDs), the Government of India has launched ‘Mission Indradhanush’ in December 2014 to increase full immunization coverage in India to at least 90% children by December 2018.
  • Mission Indradhanush provides vaccination against 7 diseases: diphtheria, whooping cough, tetanus, polio, tuberculosis, measles and hepatitis B.
  • In addition, vaccination against Japanese Encephalitis and Haemophilus influenzae type B is being provided in selected districts of the country. Vaccination against tetanus is also provided to the pregnant women.

Intensified Mission Indradhanush

  • The Intensified Mission Indradhanush (IMI) has been launched by the Government of India in 2017 to reach each and every child under two years of age and all those pregnant women who have been left uncovered under the routine immunisation programme.
  • The target under IMI is to increase the full immunization coverage to 90% by December 2018.
  • Under Intensified Mission Indradhanush, greater focus was given on urban areas which was one of the gaps of Mission Indradhanush.

 

About Tuberculosis(TB)

 
  • TB remains the world’s deadliest infectious killer. Each day, over 4000 people lose their lives to TB and close to 30,000 people fall ill with this preventable and curable disease.
  • Caused by the bacillus Mycobacterium tuberculosis, TB is an infectious disease. In most cases, TB affects the lungs (pulmonary TB) but can also affect other sites(non-pulmonary TB).
  • It is a contagion disease, which spreads when the people who are sick with pulmonary TB expel bacteria into the air, for example by coughing.
  • Rapid molecular test, Sputum smear microscopy, Culture-based methods are some of the diagnostic tests for TB.
  • Without treatment, the mortality rate from TB is high.
 

Initiatives of WHO:

  • Find. Treat. All. #EndTB: A joint initiative of the World Health Organization (WHO)with the Global Fund and Stop TB Partnership, with the aim of accelerating the TB response and ensuring access to care, in line with WHO’s overall drive towards Universal Health Coverage. 
  • A global TB report: Published by the WHO every year since 1997.
 

Initiatives in India:

  1. There is a free treatment of TB in India.
  2. India aims to eliminate TB by 2025, while the UN aims to eliminate TB by 2030.
  3. Mass BCG vaccination to prevent TB.
  4. Revised National TB Control Programme (RNTCP) was launched in 1993, offering free diagnosis and treatment for patients, rescuing them from otherwise sure death.
  5. A Rs 12,000 cr allocation of fund over the next 3 years to fight TB.
  6. A public campaign: TB Harega Desh Jeetega.

Source: https://indianexpress.com/article/explained/tb-vaccine-as-anti-covid-candidate-what-icmr-will-study-in-bcg-trial-6418161/