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Tuesday, June 02, 2020

TB vaccine as anti-Covid candidate: what ICMR will study in BCG trial

India, like many other Asian, African, and Latin American countries, has a current national BCG vaccination policy for all at birth.

Written by Karishma Mehrotra | New Delhi | Updated: May 20, 2020 7:16:20 pm
TB vaccine as anti-Covid candidate: what ICMR will study in BCG trial Small bottles labeled with a “Vaccine COVID-19” sticker and a medical syringe are seen in this illustration taken taken April 10, 2020. (Reuters Illustration: Dado Ruvic)

In a growing list of global trials on the efficacy of tuberculosis vaccines in preventing Covid-19, one is an upcoming 10-month trial being conducted by the Indian Council of Medical Research (ICMR) on the BCG vaccine.

What is the BCG vaccine?

Short for Bacillus Calmette-Guérin, 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. It has been used across the world, including in India for decades, against tuberculosis.

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, 91.9 per cent of children between the ages of 12 and 23 months have received the vaccine, according to the National Family Health Survey. Outside of some Northeastern states, almost all states have above a 90% BCG vaccination rate. According to the National Health Profile, India has a production capacity of 2,800 lakh BCG vaccine doses.

What will ICMR’s upcoming study on BCG vaccine look at?

It will focus on the vaccine’s potential in reducing the chance of Covid-19 death among those who are above age 60. With new finalised details of this study, results could be seen as early as March 2021, said lead ICMR scientist Suman Kanungo.

The study will cover 1,450 elderly people in six red and orange zones: King Edward Memorial (KEM) Hospital, Mumbai; All India Institute of Medical Sciences (AIIMS), New Delhi; National Institute for Research in Tuberculosis (NIRT), Chennai; National Institute of Occupational Health (NIOH), Ahmedabad; National Institute in Environmental Health (NIREH), Bhopal; and National Institute for Implementation Research on Non-Communicable Diseases (NIIRNCD), Jodhpur.

With paperwork in process, the recruitment should take four months while the follow-up results will take six months after that, said Kanungo. The study will be conducted in conjunction with NIRT.

In mid-April, ICMR’s head of epidemiology R R Gangakhedkar had said ICMR would not recommend the BCG vaccine until “definitive results” from a study showed possible anti-Covid immunity. Kanungo said “the study will initiate as the paperwork is on. We should have results in 10 months”. Outside of ICMR’s studies, institutional-level trials in Rohtak, Pune, Visakhapatnam, and Bhubaneswar are also assessing the potential.

What is known about this vaccine’s action in Covid patients?

The BCG vaccine has been studied in research on Covid around the world. A pre-print, population-level study by New York researchers on March 28 suggested that countries with lower vaccination and without universal BCG vaccination (such as Italy and US) saw higher Covid-19 fatalities. The study compared this pattern to countries such as South Korea and Japan, which have standing policies on the topic.

“While these data could indeed suggest a protective effect of BCG vaccination, such studies cannot provide definitive proof of causality, owing to several inherent biases,” scientists wrote in an article in Nature on April 27. “Notwithstanding these issues, 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.”

Are other countries looking into this?

Yes. The World Health Organization (WHO) has initiated trials to ascertain the potential vaccine, but has not recommended it for Covid-19 prevention. Studies are ongoing in Australia, the Netherlands, Germany, the US, and several other countries. An article in The Lancet on April 30, whose authors included the WHO Director General, stated: “BCG vaccine has been shown to reduce the severity of infections by other viruses with (a similar SARS-CoV-2) structure in controlled trials.”

A recent study in the Journal of American Medical Association found no effectiveness of BCG vaccines in Israel, which used to have a universal policy and then shifted in 1982 to only vaccinate immigrants.

What other ICMR studies are ongoing?

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. Results will be available by the end of July, said Kanungo. 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.

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In the HCQ study, researchers are looking at 1,200 to 1,500 healthcare workers who do not have Covid-19 to find out how many who have taken the drug develop Covid-19, compared to those who have not. Begun this month, the study has taken place in five sites: AIIMS Bhubaneswar, AIIMS Jodhpur, AIIMS Patna, Apollo Hospital in Chennai, Maulana Azad Medical College in Delhi, and Sir Ganga Ram Hospital in Delhi. Kanungo said ICMR intends to recruit at least two more hospitals.

On March 23, 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.

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