Varicella in Brazil: Analysis of Case Trends and Vaccination Between 2013 and 2023

Varicella is a highly contagious viral disease that predominates in childhood and, although it is mostly self-limited, can progress to more severe cases. Vaccination against this disease was incorporated into the National Immunization Program of the Unified Health System (SUS) in 2013. The objective of this study is to analyze the evolution of reported varicella cases in Brazil between 2013 and 2023, relating them to the number of doses administered of specific immunobiologics against the disease. A descriptive study was conducted with secondary data collected from the Department of Informatics of the Unified Health System (DATASUS). Annual absolute numbers of reported varicella cases and of doses administered of Human Anti-Varicella Zoster Immunoglobulin (IGHV) and the Tetraviral Vaccine in Brazil between 2013 and 2023 were analyzed. In 2013, 178,986 varicella cases were reported in Brazil and 902,921 doses were administered. In 2014, there was a 204.5% increase in doses administered (2,749,388), while cases fell by 36.6% (113,477). The downward trend in varicella notifications continued in subsequent years, with 68,700 cases in 2015, 60,802 in 2016, and 58,312 in 2017. In the same period, the number of immunizations remained high and stable, ranging between approximately 2.4 and 2.6 million per year. In 2018, cases dropped to 17,651 (a 69.7% reduction compared to 2017), accompanied by a marked increase in doses to 4,444,285 doses. The following year (2019), even with the highest vaccine volume in the historical series (4,817,860 doses), cases showed a slight increase (28,076). During the COVID-19 pandemic, a new decline was observed: 5,995 cases in 2020 and 5,339 in 2021, despite a reduction in doses administered to 4,503,601 and 3,944,030, respectively. In 2022, cases rose to 7,644, with 4,500,029 immunizations, and fell again in 2023, reaching 4,019 records. In that last year, 4,025,637 doses of immunobiologics against varicella were administered nationwide. The data confirm a strong association between increased vaccination coverage and the marked reduction in varicella cases in Brazil. Maintaining high immunization rates over the decade was essential for sustained disease control, even during the pandemic, when the number of immunizations decreased. This reinforces the importance of continuous vaccination strategies as a central tool in varicella prevention.