At this time it has been decided by the study team the the study will no longer take place in the United States.

The purpose of this study is to assess the efficacy of Bacille Calmette-Guérin (BCG) vaccination compared to placebo in reducing severe Covid-19 disease among elderly residents of skilled nursing facilities. The investigators hypothesize that BCG vaccination can reduce severity of Covid-19 disease. Patients who are residents of participating long-term care facilities (LTCFs), with the ability to understand and cooperate with study procedures, who agree to participate in the study will be randomly assigned to receive BCG vaccination or a placebo. Participants will be followed for up to twelve months to assess severity of Covid-19 outcomes.

This is a Phase III, double-blind, randomized placebo-controlled trial comparing efficacy of BCG vaccination to that of placebo in reducing severity of Covid-19. Participants will need to meet eligibility criteria in order to be included in the study. Those selected, will be asked to provide a blood or saliva sample for Covid-19 serological test and an Interferon gamma release assay (IGRA) test for tuberculosis infection, only if IGRA or tuberculin skin test (TST) result is not available from the previous year. Participants will be randomized in a 1:1 allocation to receive intradermal administration of BCG vaccination or placebo at baseline. During follow-up, the study team will extract participants information from nursing home records regarding Covid-19-like symptoms, diagnosis, outcomes, as well as any adverse side effects of BCG vaccination. At 6 and 12 months of follow up, an additional blood or saliva sample will be collected to perform a Covid-19 serological test.

The investigators will screen 2,500 individuals to enroll 2,100 participants, resulting in 1,050 receiving BCG vaccine and 1,050 receiving placebo. The proposed enrollment sample size is designed to provide 80% power to detect 60% vaccine efficacy (a relative risk of 0.4 among the vaccinated) with 0.05 type-1 error in a two-tailed test, assuming a Covid-19 attack rate of 10% in elderly NH and 38.5% severe Covid-19 among the infected patients, and a design effect = 1.2, and 15% lost during the 6-month follow-up. The number of individuals screened assumes about 20% will not be eligible/agree to be enrolled.

Note that the 60% vaccine efficacy was based on the observed three-fold decline in respiratory infections in the adolescent cohort.

Objective: To assess the efficacy of BCG vaccination compared to placebo in reducing severe Covid-19 disease among elderly residents of skilled nursing facilities.

Primary Endpoint 1: Cases of Covid-19 disease classified as severe. Severe COVID-19 disease will be defined as: COVID-19 disease with hospitalization, death, or non-hospitalized severe disease where non-hospitalized severe disease is defined as a change in status including administration of new supplemental oxygen or decline in oxygen saturation of 10%; change from ambulant to non-ambulant status of 3+ days; new change in mental status as documented in the electronic health record

The investigators will use the Cox proportional-hazards model to calculate hazard ratios for the development of severe Covid-19 between the BCG and placebo arms.

If BCG vaccine is shown to be effective in this age group, it will be of major benefit to both study participants and other elderly individuals at risk for infection and disease from Covid-19. With no other vaccine alternative currently available, an efficacy of even 50% could reduce the death rate among infected patients accordingly. BCG has been reported to have a variety of other possible benefits including reduction in the risk of TB disease, Alzheimer's Disease and reduction in other respiratory infection. Because these benefits have not been proven in clinical trials, they will not be presented to potential participants.

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

Participants and investigators and designated staff whose responsibility will be to administer the BCG vaccine or placebo will be blinded.