Active immunization through vaccination is the most effective method to reduce the spread of infectious and contagious diseases. Thus, this study analyzed the vaccination rates in the state of Maranhão in the period 2013–2022, in order to understand the implications of reducing this coverage for the reemergence of diseases that had been eradicated until then and the main outcomes. This is an analytical research of the ecological type of time series carried out in the state of Maranhão. (BCG), human rotavirus vaccine, pneumococcal vaccine 10, pentavalent vaccine (DTP + Hib + HB), meningococcal C vaccine, polio vaccine, and yellow fever (YF) vaccine. in the 19 regional health units of the state (URS). Of the seven immunobiologicals studied, the only ones to reach the recommended target for vaccination coverage were BCG and poliomyelitis, during the period of data analysis. Regarding the trend, none showed an increasing pattern during the analyzed period. Undoubtedly, vaccines are indispensable tools for preventing and combating diseases, in addition to being extremely cost-effective. In view of the results, it can be said that the population is certainly the main protagonist in this scenario, since the success or failure of immunization actions are closely associated with society's adherence. Therefore, supporting and encouraging actions that contribute to community awareness and access to vaccines are fundamental in this context.