Repurposing of the childhood vaccines: could we train the immune system against the SARS-CoV-2

Abstract

Introduction The COVID-19 pandemic is a globalized health concern caused by a beta-coronavirus named Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Since December 2019, when this outbreak flared in Wuhan, China, COVID-19 cases have been continuously rising all over the world. Due to the emergence of SARS-CoV-2 mutants, subsequent waves are flowing in a faster manner as compared to the primary wave, which is more contagious and causing higher mortality. Recently, India has emerged as the new epicenter of the second wave by mutants of SARS-CoV-2. After almost eighteen months of this outbreak, some COVID-19 dedicated therapeutics and vaccines are available, and a few are under trial, but the situation is still uncontrolled. Area covered This perspective article covers the repurposing of childhood vaccines like Bacille Calmette–Guerin (BCG), Measles, Mumps, Rubella (MMR), and Oral Polio Vaccine (OPV), which are live attenuated vaccines and have been shown the protective effect through ‘trained immunity and ‘crossreactivity.' Expert opinion This perspective article has suggested that combinatorial use of these childhood vaccines might exert a better protective effect along with the available COVID-19 therapeutic and vaccines which could be considered as a preventive option against SARS-CoV-2 infection as well as its subsequent waves.

Immunosenescence and COVID-19

“…by vaccines may in this context be a double-edged sword. On one hand, it has been shown that prior vaccinations against influenza, tuberculosis and other infections may convey increased protection from COVID-19 and postulated that ongoing vaccinations against these diseases may lessen the burden of COVID-19 ( Aspatwar et al, 2022 , Debisarun et al, 2021 , O'Neill and Netea, 2020 , Sharma, 2021 ). According to the cited authors, trained immunity may act via epigenetic reprogramming of monocytes.…”

The Challenges and Successes of Dealing with the COVID-19 Pandemic in India

“…86 More recently our group has suggested the combinatorial use of childhood vaccines (BCG, MMR and OPV) along with the COVID-19 dedicated vaccines could be a potential strategy to control the COVID-19 pandemic worldwide. 87…”

BCG Vaccination: A potential tool against COVID-19 and COVID-19-like Black Swan incidents

“…Vaccine-induced heterologous or nonspecific effects (known as off-target effects) can protect against pathogens other than their intended specific pathogen [16] . Vaccines, including BCG, OPV, MV, smallpox vaccine, and yellow fever vaccine, are believed to have nonspecific effects [13] . Originally, BCG was introduced to prevent TB, leprosy, and Buruli ulcer disease [13] .…”

“…For instance, researchers found that the SARS-CoV-2 Omicron variant (B.1.1.529) was undetectable in most participants vaccinated with mRNA-1273, BNT162b, or Ad26.COV2.S vaccines [10] , [11] . Before the COVID-19 specific vaccines were available, some existing vaccines, such as Bacille Calmette-Guérin (BCG), measles vaccine (MV), oral polio vaccine (OPV), and Measles-Mumps-Rubella (MMR), had started to be repurposed to prevent SARS-CoV-2 infection [12] , [13] . BCG is a live attenuated strain derived from Mycobacterium bovis in 1921 and has been widely used for preventing tuberculosis (TB) in children globally [5] , [14] .…”