Abstract
Vaccination is one of the greatest public health interventions, based on its safety and effectiveness, but vaccination does not always mean immunization. Numerous aspects related both to the individual that receives the vaccine and the specificity of each vaccine administered are part of the process of obtaining adequate immunization, and it is essential to observe the aspects in order to avoid vaccine failures. The analysis of immunogenicity and effectiveness studies for the measles, varicella, and mumps vaccines point to the need to incorporate two doses into the basic vaccination calendars in order to control these diseases. Epidemiological studies that analyzed outbreaks of these diseases identified cases in individuals that received two doses of the vaccine, which may indicate likely secondary failure. For the yellow fever vaccine, the current discussion lies in the ideal number of doses for individual protection. The World Health Organization recommends a single dose for life. Despite the few reports in the literature concerning vaccine failures, immunogenicity studies demonstrate waning protection over the years, mainly in the pediatric age bracket. In the current scenario of elimination and control of diseases, associated with the decrease in the circulation of the wild-type viruses, the role of epidemiological surveillance is crucial for expanding knowledge on the multiple factors involved, culminating in vaccine failures and the emergence of outbreaks. Outbreaks of vaccine-preventable diseases negatively impact the credibility of immunization programs, leading to low vaccination coverage rates and interfering in vaccination's success.
Highlights
Vaccination is one of the greatest public health interventions, based on cost, effectiveness, safety, and efficacy
The study aimed to analyze vaccine failure with the yellow fever, measles, varicella, and mumps vaccines in Brazil and in other countries and to assess the most adequate number of doses based on data from the scientific literature, websites of immunization programs, and relevant publications related to vaccination
Vaccine failures were identified with two doses and varied between the vaccines, characterizing probable secondary failure
Summary
Vaccination is one of the greatest public health interventions, based on cost, effectiveness, safety, and efficacy. Between vaccinating and obtaining protection, that is, immunity, multifactor analyses come into play, and the goal becomes more complex. This process requires pharmacovigilance for monitoring adverse reactions to vaccines, immunization errors, and vaccine failures. The study aimed to analyze vaccine failure with the yellow fever, measles, varicella, and mumps vaccines in Brazil and in other countries and to assess the most adequate number of doses based on data from the scientific literature, websites of immunization programs, and relevant publications related to vaccination. The World Health Organization (WHO) recommends a single dose of the yellow fever vaccine for all age brackets, based on the vaccine’s good efficacy and the few reports of vaccine failures 6. (2) various studies have demonstrated vaccine failures for other important diseases such as measles, varicella, and mumps, raising the need to evaluate vaccine failures and the setted vaccination regimens [7,8,9,10]
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