Under what conditions is the effectiveness of a vaccine measured?

When a vaccine begins to be used massively, then you have to measure its effectiveness, which is measured in real life and is a different term. In general, the effectiveness values ​​are lower than those obtained in clinical trials. That is, effectiveness is measured when a vaccine is applied in real life conditions, in the field, and is administered to everyone who needs to be vaccinated from 19 years of age. In the population there may be people with greater or lesser immune competence. In fact, vaccinations from the most vulnerable groups are favored, because they are precisely the groups where there may be a higher incidence of severe disease and mortality may be higher. Vaccination is started for these people, even if they are the individuals who have a less powerful immune response, but even so the vaccination will favor them and better prepare them for infection with the virus. In fact, in the case of the most massive use of the vaccine, we have used it in the intervention study that was carried out on BioCubafarma medical personnel and health personnel; then, in the sanitary intervention, and later, as of July 9, in the massive vaccination. But, based on the results obtained, specific risk groups were also vaccinated, such as nephropathy patients and also pregnant and lactating mothers.