{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,16]],"date-time":"2026-05-16T00:41:31Z","timestamp":1778892091725,"version":"3.51.4"},"reference-count":123,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2022,6,23]],"date-time":"2022-06-23T00:00:00Z","timestamp":1655942400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>The Bacille Calmette-Gu\u00e9rin or BCG vaccine, the only vaccine available against Mycobacterium tuberculosis can induce a marked Th1 polarization of T-cells, characterized by the antigen-specific secretion of IFN-\u03b3 and enhanced antiviral response. A number of studies have supported the concept of protection by non-specific boosting of immunity by BCG and other microbes. BCG is a well-known example of a trained immunity inducer since it imparts \u2018non-specific heterologous\u2019 immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the recent pandemic. SARS-CoV-2 continues to inflict an unabated surge in morbidity and mortality around the world. There is an urgent need to devise and develop alternate strategies to bolster host immunity against the coronavirus disease of 2019 (COVID-19) and its continuously emerging variants. Several vaccines have been developed recently against COVID-19, but the data on their protective efficacy remains doubtful. Therefore, urgent strategies are required to enhance system immunity to adequately defend against newly emerging infections. The concept of trained immunity may play a cardinal role in protection against COVID-19. The ability of trained immunity-based vaccines is to promote heterologous immune responses beyond their specific antigens, which may notably help in defending against an emergency situation such as COVID-19 when the protective ability of vaccines is suspicious. A growing body of evidence points towards the beneficial non-specific boosting of immune responses by BCG or other microbes, which may protect against COVID-19. Clinical trials are underway to consider the efficacy of BCG vaccination against SARS-CoV-2 on healthcare workers and the elderly population. In this review, we will discuss the role of BCG in eliciting trained immunity and the possible limitations and challenges in controlling COVID-19 and future pandemics.<\/jats:p>","DOI":"10.3390\/vaccines10071006","type":"journal-article","created":{"date-parts":[[2022,6,23]],"date-time":"2022-06-23T22:43:00Z","timestamp":1656024180000},"page":"1006","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Fiction and Facts about BCG Imparting Trained Immunity against COVID-19"],"prefix":"10.3390","volume":"10","author":[{"given":"Gurpreet","family":"Kaur","sequence":"first","affiliation":[{"name":"Immunology Laboratory, Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sanpreet","family":"Singh","sequence":"additional","affiliation":[{"name":"Immunology Laboratory, Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology, Chandigarh 160036, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1577-8195","authenticated-orcid":false,"given":"Sidhanta","family":"Nanda","sequence":"additional","affiliation":[{"name":"Immunology Laboratory, Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7029-2489","authenticated-orcid":false,"given":"Mohammad Adeel","family":"Zafar","sequence":"additional","affiliation":[{"name":"Immunology Laboratory, Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6684-6744","authenticated-orcid":false,"given":"Jonaid Ahmad","family":"Malik","sequence":"additional","affiliation":[{"name":"Immunology Laboratory, Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mohammad Umar","family":"Arshi","sequence":"additional","affiliation":[{"name":"Immunology Laboratory, Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Taruna","family":"Lamba","sequence":"additional","affiliation":[{"name":"Immunology Laboratory, Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Javed Naim","family":"Agrewala","sequence":"additional","affiliation":[{"name":"Immunology Laboratory, Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, India"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,6,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1707","DOI":"10.1128\/iai.55.7.1707-1714.1987","article-title":"Mycobacterium bovis BCG-induced protection against cutaneous and systemic Leishmania major infections of mice","volume":"55","author":"Fortier","year":"1987","journal-title":"Infect. 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