2.3. Randomization and Blinding
ADVERSE EVENTS
Randomization was performed using the sealed envelope method on the day of the 1st vaccination. Distribution of the participants into Vaccine or Placebo Groups in the 18–60 age cohort was carried out using random number generator software.After assigning a three-digit randomization number to a participant, a sealed envelope with the randomization number was given to a healthcare worker who administered the vaccine. The participants in the 18–60 age cohort did not know which preparation they were receiving. After the vaccination, a separate physician observed the participant for possible AEs. The laboratory specialists were provided with the samples marked with coded numbers and thus were also blinded.All study participants in the 60+ age cohort received randomization numbers used for the monitoring of possible adverse events (AEs) and immunogenicity assessment, but no further distribution between groups was performed. All participants in the 60+ age cohort received the vaccine.