Mw: A Potential Non-Specific Vaccine as First Response to Future Viral Pandemics before SpecificVaccines are Available - Some Lessons from COVID-19 Pandemic

In absence of an effective drug or vaccine in the initial phase of COVID-19 pandemic, authors started searching the literature to repurpose existing drugs/vaccines. Mw vaccine, a heat-killed Mycobacterium W, is routinely used by clinicians to boost the immune response of leprosy patients in India as an innate immune response immunomodulator. After detailed deliberations, on September 2020, the corresponding author submitted an emergency protocol to use Mw as a booster of Innate Immunity of doctors and HCWs looking after COVID-19 Positive patients in Himachal Pradesh, India. Later Mw was arranged and 21 persons were immunised with two site intradermal 0.1 mL doses of Mw vaccine in September 2020. Later two booster doses were given one each (0.1 mL) at 3 months’ interval. Regular RT-PCR was done and two persons who received vaccine were found to be positive for COVID-19. One person with diabetic status was found to have symptoms of sore throat, fatigue and high fever that responded in home isolation, without oxygen requirement and the other person was positive but asymptomatic. Subsequent studies proved that the prophylactic effect of Mw manifests quickly following the first administration of Mw, widening of the gap between two arms over time, reflecting ongoing immune remodelling. With the current COVID-19 vaccination schedule across the world and the emergence of breakthrough infection, Mw should be useful in the current pandemic too and must be tried. In future viral pandemic, we should think of using Mw as the first response non-specific vaccine till a specific vaccine is available, as Mw does not require antigen-specific changes and can be used immediately as universal vaccine. Mw stimulates innate response against viral mutation and variants as well.