inclusion criteria: to be eligible to participate in this study, the participant must meet the following criteria: • be older than 18 years old. observation: the elderly is at risk for severe forms of covid-19, therefore, the evidence in this age group is very relevant. however, they can also be a first priority population to receive a specific vaccine, limiting the time to follow-up on the study. in addition, influenza and mmr vaccines can lead to a lower immune system in the elderly than in young people. therefore, it is likely that a more rational choice will be to carry out the study in a young population.

inclusion criteria: to be eligible to participate in this study, the participant must meet the following criteria: • be older than 18 years old. observation: the elderly is at risk for severe forms of covid-19, therefore, the evidence in this age group is very relevant. however, they can also be a first priority population to receive a specific vaccine, limiting the time to follow-up on the study. in addition, influenza and mmr vaccines can lead to a lower immune system in the elderly than in young people. therefore, it is likely that a more rational choice will be to carry out the study in a young population.