BCG to Reduce Absenteeism Among Health Care Workers During the COVID-19 Pandemic

The main hypothesis for this study is that BCG vaccination of HCW reduces unplanned absenteeism due to illness by 20%. Trial design Single-blind, parallel-group placebo-controlled adaptive multicentre trial, with block-randomisation 1:1 (treatment:placebo) in blocks of 20 within strata defined by gender (male/female) and occupational group (doctors/ nurses/other) to an intradermal standard 0.1 ml dose of BCG vaccine or placebo (saline) including a total of 1050 HCW (BCG arm and placebo arm). Study population: Health Care Workers defined as a person who delivers care and services to the sick and ailing either directly as doctors and nurses or indirectly as aides, helpers, laboratory technicians, or even medical waste handlers. Intervention: The intervention will consist of the administration of an intradermal injection of a standard 0.1 ml adult dose of attenuated Mycobacterium bovis BCG (Bacillus Calmette-Guerin), Danish strain 1331, 2-8 × 10\*5 CFU or the placebo comparator: intradermal standard 0.1 ml saline solution (NaCl 0.9%). Both BCG and saline solution will be injected in the skin over the upper deltoid muscle. Blinding: The BCG vaccine will be administered by study physicians/nurses, who are not blinded but also not involved in the data collection. Participants, data collectors and data entry clerks will be blinded to the treatment allocation. In case of serious adverse events, the participant can be unblinded after consultation with the investigator or the vaccinating physician/nurse. When the study has ended, all participants will receive information about the intervention that they received. Follow-up: Follow-up will last for 6 months (182 days). Every second week, participants will be contacted over telephone and interviewed for symptoms and absenteeism from work. By the end of follow-up, participants will be invited for another POC test for COVID-19 serology. Sample size: The sample size was calculated on the basis of the primary hypothesis. A total of 1050 HCW randomized with an estimated loss to follow-up of 5%, and a mean number of days off work due to illness in the control group of 5 days (SD=5) over a 6-month period will demonstrate a reduction among BCG vaccinated of 20% for a mean absence of 4 days (80% power and alpha 0.05). The estimated loss to follow-up (5%) was based on past telephone-based surveys conducted in Mozambique and Bissau.