BCG revaccination of health workers in Brazil to improve innate immune responses against COVID-19: A structured summary of a study protocol for a randomised controlled trial

Abstract

Objectives The BCG vaccine, widely used in Brazil in new-borns, induces adjuvant protection for several diseases, including childhood virus infections. BCG activates monocytes and innate memory NK cells which are crucial for the antiviral immune response. Therefore, strategies to prevent COVID-19 in health workers (HW) should be carried out to prevent them becoming unwell so that they can continue to work during the pandemic. The hypothesis is that BCG will improve the innate immune response and prevent symptomatic infection or COVID-19 severity. The primary objective is to verify the effectiveness and safety of the BCG vaccine to prevent or reduce incidence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in the city of Goiânia (Brazil) among HW previously vaccinated with BCG and also its severity and mortality during the pandemic of the disease. Secondary objectives are to estimate the incidence of COVID-19 among these professionals and the innate immune response elicited to BCG. Trial design This a phase II trial for repositioning BCG as a preventive strategy against COVID-19. The trial is an open-label, parallel-group randomised clinical trial, comparing HW vaccinated with BCG and HW not vaccinated. Participants The trial will recruit 800 HW of Goiânia - Goiás, Brazil to reach a total of 400 HW included after comorbidities questioning and laboratorial evaluation. Eligibility criteria: Any HW presenting BCG vaccination scar with direct contact with suspected COVID-19 patients for at least 8 hours per week, whether in hospital beds, ICU, or in transportation or admission (nurses, doctors, physiotherapists, nutritionists, receptionists, etc.) who have negative IgM and IgG COVID-19 test. Participants with any of the following characteristics will be excluded: - Have had in the last fifteen days any signs or symptoms of virus infection, including COVID-19; - Have had fever in the last fifteen days; - Have been vaccinated fifteen days before the inclusion; - Have a history or confirmation of any immunosuppressive disease such as HIV, presented solid tumour in the last two years or autoimmune diseases; - Are under preventive medication with antibiotics, steroid anti-inflammatories, or chemotherapy; - Have less than 500 neutrophils per mL of blood; - Have previously been diagnosed with tuberculosis; - Are breastfeeding or pregnant; - Are younger than 18 years old; - Are participating as an investigator in this clinical trial. Intervention and comparator HW will be randomized into the BCG vaccinated group or the BCG unvaccinated control group. The BCG vaccinated group will receive in the right arm, intradermally, a one off dose of 0.1 mL corresponding to approximately 2 x105 to 8 x105 CFU of live, freeze-dried, attenuated BCG Moscow 361-I, Bacillus Calmette Guerin vaccine (Serum Institute of India PVT. LTD.). The unvaccinated control group will not be vaccinated. The HW allocated in both groups will be followed up at specific times points until 180 days post inclusion. The vaccinated and control groups will be compared according to COVID-19 related outcomes. Main outcomes The primary outcomes are the incidence coefficient of infection by SARS-CoV-2 determined by RT-PCR of naso-oropharyngeal swab specimen or rapid lateral flow IgG and IgM test, and presence of general COVID-19 symptoms, disease severity and admission to hospital during the 180 days of follow up. The secondary outcome is the innate immune response elicited 15-20 days after vaccination. Randomisation The vaccine vial contains approximately 10 doses. In order to optimize the vaccine use, the randomisation was performed in blocks of 20 participants using the platform randomization.com [http://www.jerrydallal.com/random/permute.htm]. The randomization was prepared before any HW inclusion. The results were printed and inserted in sealed envelopes that were numbered with BCG-001 to BCG-400. The printed results as well the envelopes had the same numbers. At the time of the randomisation, each participant that meets the inclusion criteria will receive a consecutive participant number [BCG-001-BCG-400]. The sealed envelope with the assigned number, blinded to the researchers, will be opened in front of the participant and the arm allocation will be known. Blinding (masking) There is no masking for the participants or for the healthcare providers. The study will be blinded to the laboratory researchers and to those who will be evaluating the outcomes and performing the statistical analyses. In this case, only the participant identification number will be available. Numbers to be randomised (sample size) Four hundred heath workers will be randomised in two groups. Two hundred participants will be vaccinated, and 200 participants will not be vaccinated. Trial Status The protocol approved by the Brazilian Ethical Committee is the seventh version, number CAAE: 31783720.0.0000.5078. The trial has been recruiting since September 20th, 2020. The clinical trial protocol was registered on August 5th, 2020. It is estimated that recruitment will finish by March 2021. Trial registration The protocol number was registered on August 5th, 2020 at REBEC (Registro Brasileiro de Ensaios Clínicos). Register number: RBR-4kjqtg and WHO trial registration number UTN: U1111-1256-3892. Full protocol The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

BCG‐induced protection against Mycobacterium tuberculosis infection: Evidence, mechanisms, and implications for next‐generation vaccines

“…130 It has been proposed that BCG may also offer protection against infection with SARS-CoV-2 and reduce severity of COVID-19 disease, 131 with some studies suggesting an association between universal BCG vaccination and reduced COVID-19 mortality, 132 while others did not. 133 Several randomized trials in healthcare workers 134 and elderly patients that are underway or pending final analysis will provide final proof for a protective effect of BCG against COVID-19.…”

A rapid review of recent advances in diagnosis, treatment and vaccination for COVID-19

“…Another large trial recruiting 800 participants has started in Brazil, with recruitment being completed by March 2021. The follow-up is for six months; the results will likely be available by the end of this year [89] . A recent study among a cohort of health care workers concluded that a history of BCG vaccination has been associated with a decrease in anti-SARS-CoV-2 IgG seroprevalence and a decrease in the number of participants self-reported with COVID-19-related clinical symptoms in this cohort [90] .…”

Harnessing the Neurobiology of Resilience to Protect the Mental Well-Being of Healthcare Workers During the COVID-19 Pandemic

“…From a bottom-up perspective, animal models have shown that immunization with specific substances, such as myelin-related peptides ( Lewitus et al, 2008 ), and certain mycobacterial strains ( Reber et al, 2016 ; Loupy et al, 2021 ) can attenuate stress-induced anxiety and promote resilience via alterations in immune functioning, such as inhibition of stress-related increases in IL-6. The latter finding is of particular significance in the context of the COVID-19 pandemic, as it has been noted that immunization against Mycobacterium tuberculosis exerts a potential protective effect against COVID-19 mortality ( Li, 2021 ) and trials of BCG immunization in healthcare workers for this purpose are in progress ( Junqueira-Kipnis et al, 2020 ; Madsen et al, 2020 ). Stress-induced alterations in immune function are also under epigenetic control and may be amenable to modulation in this manner, as discussed in the next section.…”