ABSTRACT
BackgroundBacillus Calmette-Guerin (BCG) vaccination has been hypothesised to reduce SARS-CoV-2 infection, severity, and/or duration via trained immunity induction. MethodsHealthcare workers (HCWs) in 9 Dutch hospitals were randomised to BCG or placebo vaccination (1:1) in March/April 2020 and followed for one year. They reported daily symptoms, SARS-CoV-2 test results, and healthcare-seeking behaviour via a smartphone application, and donated blood for SARS-CoV-2 serology at two time points. Results1,511 HCWs were randomised and 1,309 analysed (665 BCG and 644 placebo). Of the 298 infections detected during the trial, 74 were detected by serology only. The SARS-CoV-2 incidence rates were 0.25 and 0.26 per person-year in the BCG and placebo groups, respectively (incidence rate ratio=0.95; 95% confidence interval 0.76-1.21; p=0.732). Only three participants required hospitalisation for COVID-19. The proportions of participants with asymptomatic, mild, or mild-to-moderate infections, and the mean infection durations, did not differ between randomisation groups. Unadjusted and adjusted logistic regression and Cox proportional hazards models showed no differences between BCG and placebo vaccination for any of these outcomes either. The percentage of participants with seroconversion (7.8% versus 2.8%; p=0.006) and mean anti-S1 antibody concentration (13.1 versus 4.3 IU/ml; p=0.023) were higher in the BCG than placebo group at 3 months but not at 6 or 12 months post-vaccination. ConclusionsBCG vaccination of HCWs did not reduce SARS-CoV-2 infections nor infection duration or severity (on a scale from asymptomatic to moderate). In the first 3 months after vaccination, BCG vaccination may enhance SARS-CoV-2 antibody production during SARS-CoV-2 infection.
ABSTRACT
BackgroundThere is an urgent need for fair and equitable access to safe and effective vaccines to end the COVID-19 pandemic. Shortages in reagents and vaccines are a major challenge, as well as limited knowledge on dose response relationship with mRNA COVID-19 vaccines. We explored intradermal fractional dose administration of a mRNA SARS-CoV-2/COVID-19 vaccine as a potential dose-sparing strategy. MethodsWe conducted a proof-of-concept, dose-escalation, open-label, randomised-controlled vaccine trial (IDSCOVA) in healthy adults aged 18-30 years. To test initial safety, ten participants received 10 {micro}g mRNA-1273 vaccine through intradermal injection at day 1 and 29. Following a favourable safety review, thirty participants were 1:1 randomised to receive 20 {micro}g mRNA-1273 either intradermally or intramuscularly. The primary endpoint was tolerability and safety. The secondary endpoint was seroconversion and specific IgG concentration against SARS-CoV-2 spike S1 and Receptor Binding Domain (RBD) after the second dose at day 43. We compared results to two historical cohorts of non-hospitalised COVID-19 patients and vaccinated individuals. FindingsThirty-eight of forty included participants (median age 25 years) completed the study. There were no serious adverse events. Self-reported local adverse reactions after intradermal delivery were mild, both in the 10 {micro}g and the 20 {micro}g group. In the higher dose group, systemic adverse reactions were more common, but still well tolerated. All 38 participants mounted substantially higher IgG-anti-S1 and IgG-anti-RBD concentrations at day 43 than COVID-19 controls. At day 43, anti-S1 (95% CI) was 1,696 (1,309-2,198) BAU/mL for the 10 {micro}g intradermal group, 1,406 (953{middle dot}5-2,074) BAU/mL for the 20 {micro}g intramuscular group and 2,057 (1,421-2,975) BAU/mL for the 20 {micro}g intradermal group. Anti-S1 was 107{middle dot}2 (63-182{middle dot}2) BAU/mL for the convalescent plasma control group and 1,558 (547{middle dot}8-4,433) BAU/mL for the individuals vaccinated with 100 {micro}g mRNA-1273. InterpretationIntradermal administration of 10 {micro}g and 20 {micro}g mRNA-1273 vaccine was well tolerated and safe, and resulted in a robust antibody response. Intradermal vaccination has the potential to be deployed for vaccine dose-sparing. FundingThe trial was supported by crowdfunding (Wake Up to Corona).
