Prevalence and titers of yellow fever virus neutralizing antibodies in previously vaccinated adults

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: Karina Takesaki Miyaji, Vivian Iida Avelino-Silva, Marisol Simões, Marcos da Silva Freire, Carlos Roberto de Medeiros, Patrícia Emilia Braga, Maria Angélica Acalá Neves, Marta Heloisa Lopes, Esper Georges Kallas, Ana Marli Christovam Sartori
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP)
• Subjects: Elderly; Immunization; Neutralizing antibody; Seroprevalence; Yellow fever vaccine; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1590/s1678-9946201759002; https://doaj.org/article/e257c60a80174916bd26f21e301dec00

ABSTRACT Introduction: The World Health Organization (WHO) recommends one single dose of the Yellow Fever (YF) vaccine based on studies of antibody persistency in healthy adults. We assessed the prevalence and titers of YF virus neutralizing antibodies in previously vaccinated persons aged 60 years, in comparison to younger adults. We also evaluated the correlation between antibody titers and the time since vaccination among participants who received one vaccine dose, and the seropositivity among participants vaccinated prior to or within the past 10 years. Methods: previously vaccinated healthy persons aged 18 years were included. YF virus neutralizing antibody titers were determined by means of the 50% Plaque Reduction Neutralization Test. Results: 46 persons aged 60 years and 48 persons aged 18 to 59 years were enrolled. There was no significant difference in the prevalence of YF virus neutralizing antibodies between the two groups (p = 0.263). However, titers were significantly lower in the elderly (p = 0.022). There was no correlation between YF virus neutralizing antibody titers and the time since vaccination. There was no significant difference in seropositivity among participants vaccinated prior to or within the past 10 years. Conclusions: the clinical relevance of the observed difference in YF virus neutralizing antibody titers between the two groups is not clear.