inclusion: * residents of a participating ltcf * 70 years or older * ability to understand and cooperate with study procedures including dressing care. * nursing home staff or the research team will ensure participants are correctly doing dressing care. exclusion: * previous or current sars-cov2 infection/covid-19 disease defined by documentation of disease in clinical chart or positive pcr test. * previous or known active tb disease * does not have an established proxy or guardian, but has cognitive impairment that would prohibit the participant from fully understanding the extent of study requirements and risks, or prohibit their ability to provide informed consent. * obesity (body mass index \[bmi\] \> 35) * fever (\>38 c) within the past 24 hours * current or historic serious underlying medical conditions: * hiv+ * history of organ or bone marrow transplantation * history of major immunodeficiency disorder * active solid or hematologic malignancy diagnosed within the past two years * presence of significant neurologic disease, eg. alzheimer's disease * receipt of any of the following drugs: * currently taking immunosuppressive or immunomodulatory drugs (inhalers and/or prednisone are acceptable to take) * the prednisone doses equivalent \> 2 mg/kg or \> 20 mg per day of prednisone administered for \>/= 2 weeks are immunosuppressive and should be avoided with live vaccines. * expect to receive chemotherapy in the coming six months, receipt of chemotherapy in the past six months or undergoing chemotherapy * currently on any anti-cytokine therapy * taking metformin treatment * suspicion of active viral or bacterial infection * plan to leave the nursing home within the next 6 months * taking part in another intervention-based trial for covid-19 * allergy to any component of the bcg vaccine or an anaphylactic or allergic reaction to a previous dose of bcg vaccination

inclusion: * residents of a participating ltcf * 70 years or older * ability to understand and cooperate with study procedures including dressing care. * nursing home staff or the research team will ensure participants are correctly doing dressing care. exclusion: * previous or current sars-cov2 infection/covid-19 disease defined by documentation of disease in clinical chart or positive pcr test. * previous or known active tb disease * does not have an established proxy or guardian, but has cognitive impairment that would prohibit the participant from fully understanding the extent of study requirements and risks, or prohibit their ability to provide informed consent. * obesity (body mass index \[bmi\] \> 35) * fever (\>38 c) within the past 24 hours * current or historic serious underlying medical conditions: * hiv+ * history of organ or bone marrow transplantation * history of major immunodeficiency disorder * active solid or hematologic malignancy diagnosed within the past two years * presence of significant neurologic disease, eg. alzheimer's disease * receipt of any of the following drugs: * currently taking immunosuppressive or immunomodulatory drugs (inhalers and/or prednisone are acceptable to take) * the prednisone doses equivalent \> 2 mg/kg or \> 20 mg per day of prednisone administered for \>/= 2 weeks are immunosuppressive and should be avoided with live vaccines. * expect to receive chemotherapy in the coming six months, receipt of chemotherapy in the past six months or undergoing chemotherapy * currently on any anti-cytokine therapy * taking metformin treatment * suspicion of active viral or bacterial infection * plan to leave the nursing home within the next 6 months * taking part in another intervention-based trial for covid-19 * allergy to any component of the bcg vaccine or an anaphylactic or allergic reaction to a previous dose of bcg vaccination

inclusion: - residents of a participating ltcf - 70 years or older - ability to understand and cooperate with study procedures including dressing care. - nursing home staff or the research team will ensure participants are correctly doing dressing care. exclusion: - previous or current sars-cov2 infection/covid-19 disease defined by documentation of disease in clinical chart or positive pcr test. - previous or known active tb disease - does not have an established proxy or guardian, but has cognitive impairment that would prohibit the participant from fully understanding the extent of study requirements and risks, or prohibit their ability to provide informed consent. - obesity (body mass index [bmi] > 35) - fever (>38 c) within the past 24 hours - current or historic serious underlying medical conditions: - hiv+ - history of organ or bone marrow transplantation - history of major immunodeficiency disorder - active solid or hematologic malignancy diagnosed within the past two years - presence of significant neurologic disease, eg. alzheimer's disease - receipt of any of the following drugs: - currently taking immunosuppressive or immunomodulatory drugs (inhalers and/or prednisone are acceptable to take) - the prednisone doses equivalent > 2 mg/kg or > 20 mg per day of prednisone administered for >/= 2 weeks are immunosuppressive and should be avoided with live vaccines. - expect to receive chemotherapy in the coming six months, receipt of chemotherapy in the past six months or undergoing chemotherapy - currently on any anti-cytokine therapy - taking metformin treatment - suspicion of active viral or bacterial infection - plan to leave the nursing home within the next 6 months - taking part in another intervention-based trial for covid-19 - allergy to any component of the bcg vaccine or an anaphylactic or allergic reaction to a previous dose of bcg vaccination

inclusion: - residents of a participating ltcf - 70 years or older - ability to understand and cooperate with study procedures including dressing care. - nursing home staff or the research team will ensure participants are correctly doing dressing care. exclusion: - previous or current sars-cov2 infection/covid-19 disease defined by documentation of disease in clinical chart or positive pcr test. - previous or known active tb disease - does not have an established proxy or guardian, but has cognitive impairment that would prohibit the participant from fully understanding the extent of study requirements and risks, or prohibit their ability to provide informed consent. - obesity (body mass index [bmi] > 35) - fever (>38 c) within the past 24 hours - current or historic serious underlying medical conditions: - hiv+ - history of organ or bone marrow transplantation - history of major immunodeficiency disorder - active solid or hematologic malignancy diagnosed within the past two years - presence of significant neurologic disease, eg. alzheimer's disease - receipt of any of the following drugs: - currently taking immunosuppressive or immunomodulatory drugs (inhalers and/or prednisone are acceptable to take) - the prednisone doses equivalent > 2 mg/kg or > 20 mg per day of prednisone administered for >/= 2 weeks are immunosuppressive and should be avoided with live vaccines. - expect to receive chemotherapy in the coming six months, receipt of chemotherapy in the past six months or undergoing chemotherapy - currently on any anti-cytokine therapy - taking metformin treatment - suspicion of active viral or bacterial infection - plan to leave the nursing home within the next 6 months - taking part in another intervention-based trial for covid-19 - allergy to any component of the bcg vaccine or an anaphylactic or allergic reaction to a previous dose of bcg vaccination