The 100-yr-old BCG vaccine for TB is being tested against the novel coronavirus

Monday, April 6th, 2020

The BCG vaccine has an unusual history:

It was inspired in the 1800s by the observation that milkmaids did not develop tuberculosis. The vaccine is named after its inventors, Dr. Albert Calmette and Dr. Camille Guerin, who developed it in the early 1900s from mycobacterium bovis, a form of tuberculosis that infects cattle.

The scientists cultured bacterial scrapings from cow udders, and continued to culture bovine TB for over a decade until it was weak enough that it no longer caused virulent disease when given to lab animals.

The weakened virus was first used in humans in 1921 and was widely adopted after World War II. Now BCG is primarily used in the developing world and in countries where TB is still prevalent, where it is given to over 100 million babies a year.

Like other vaccines, BCG has a specific target: TB. But evidence accumulating over the past decade suggests the vaccine also has so-called off-target effects, reducing viral illnesses, respiratory infections and sepsis, and appears to bolster the body’s immune system.

The idea is an offshoot of the “hygiene hypothesis,” which suggests that the modern emphasis on cleanliness has deprived children of exposure to germs. The lack of “training” has resulted in weakened immune systems, less able to resist disease.

One of the earliest studies hinting at the broad benefits of BCG vaccination was a randomized trial of 2,320 babies in Guinea-Bissau in West Africa, published in 2011, that reported that death rates among low-birth-weight babies were dramatically reduced after vaccination. A follow-up trial reported that infectious-disease mortality rates in low-birth-weight babies who were vaccinated were cut by more than 40%.

Other epidemiological studies — including a 25-year study of over 150,000 children in 33 countries — have reported a 40% lower risk of acute lower respiratory tract infections in children who received a BCG vaccine. A study in the elderly found that consecutive BCG vaccinations reduced the incidence of acute upper respiratory tract infections.

A recent review by the World Health Organization concluded that BCG had beneficial “off-target effects,” and recommended doing more trials of the vaccine against a wider range of infections.


There is little evidence yet that the vaccine will blunt infection with the coronavirus, but a series of clinical trials may answer the question in just months.

On Monday, scientists in Melbourne, Australia, started administering the BCG vaccine or a placebo to thousands of physicians, nurses, respiratory therapists and other health care workers — the first of several randomized controlled trials intended to test the vaccine’s effectiveness against the coronavirus.


A clinical trial of 1,000 health care workers began 10 days ago in the Netherlands, said Dr. Mihai Netea, an infectious disease specialist at Radboud University Medical Center in Nijmegen. Eight hundred health care workers have already signed up. (As in Australia, half of the participants will receive a placebo.)


  1. Sam J. says:

    Off topic but I belive people here might be interested in this. I was reading ” Red Plenty: Inside the Fifties’ Soviet Dream”
    by Francis Spufford, which I liked, and it had some other books mentioned in it. One was

    Pioneers of Soviet Computing

    which is also interesting if you like the books looking at technical history.

  2. Buckethead says:

    I remember reading Heart of the Comet by Greg Benford and David Brin, which centered on a manned mission to Halley’s comet in 2061. There was a lot of nice speculation as you’d expect. But one thing that stuck in my mind ever since was that one of the physician’s primary duties was releasing tailored viruses and diseases into the population in order to keep everyone healthy and their immunes systems in prime working order.

    It was the first time that I’d ever heard anything like that, and over the years I’ve seen a lot of reports/studies that point to it being essentially correct.

  3. Peter Whitaker says:

    Bat cheese mongers have been totally immune to the virus.

  4. CVLR says:

    Peter: “Bat cheese mongers have been totally immune to the virus.”


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