Initial evaluation of universal immunization with a single dose against hepatitis A virus in Central Brazil

Abstract

Vaccination against the hepatitis A virus (HAV) administered in two doses has been used effectively in universal child immunization programs in several countries. A single-dose vaccination was adopted in some low-income countries in an attempt to reduce costs without losing effectiveness. In 2014, single-dose universal vaccination was introduced in Brazil for children aged two years. Since such strategy is still not universally accepted, its efficacy should be compared to the two-dose strategy. To assess the humoral response after the single-dose HAV vaccination schedule, a cross-sectional study was conducted in Primavera do Leste, in Mato Grosso state, Central Brazil, including 265 children vaccinated through the National Immunization Program. Blood was collected by using a digital puncture and further applied to filter paper cards. Anti-HAV was detected in 218 out of 265 dried blood spots (DBS). Blood venous samples were collected from 34 out of 47 children who were not anti-HAV positive in DBS samples. Eighteen of them tested positive for anti-HAV, giving a final score of 93.6% (236/252) of seropositivity. In conclusion, this study demonstrated a high rate of anti-HAV positivity in the short term after single-dose hepatitis A vaccination in the population investigated. Moreover, the DBS was shown to be a reliable tool for detecting anti-HAV antibodies.

The Impact of an Inactivated Hepatitis A Vaccine with One Dose in Brazil: A Retrospective Time-Series

“…To our knowledge, this is the first study using interrupted time-series analysis to evaluate the impact of introducing a hepatitis A vaccine into the NIP on hepatitis A incidence rates, in the Brazilian population. Previous studies have demonstrated important reductions of hepatitis A incidence in all regions of Brazil after the vaccine introduction using other methodologies [9,13,14,15]. We found a significant immediate reduction (level change) of hepatitis A incidence rates in the overall population as well as in the target population for vaccination.…”

“…Longer term studies from Argentina have shown protective antibodies against HAV in 97.0% and 87.6% of Argentinean children after 9 and 11 years of the introduction, respectively [34]. In Brazil, a preliminary study demonstrated that 93.6% of children seroconverted 30 days after the immunization [15]. Further long-term assessments in the Brazilian population are required to confirm the seroprotective effect of a single-dose HAV vaccine.…”

A Study of Hepatitis A Seroprevalence in a Paediatric and Adolescent Population of the Province of Florence (Italy) in the Period 2017–2018 Confirms Tuscany a Low Endemic Area

“…Moreover, 4/7 vaccinated subjects belonging to our sample received a single dose of HAV vaccine showing how even a single administration was effective in inducing detectable antibodies in the serum years later. The efficacy in terms of duration of even a single dose is the basis of the one-shot universal vaccination strategy adopted by some countries to contain costs [ 39 , 40 ].…”

Is hepatitis A virus infection under control? lessons in the application of viral sequencing for the development of vaccination schemes in emergency situations

“…The World Health Organization (WHO) recommends universal vaccination against HAV by including two doses in the national immunization schedules for children aged >1 year if justified based on the data of acute HAV incidence, declining endemicity from high to intermediate and cost-effectiveness [5]. However, some low-income countries are implementing a single dose as an optimal schedule [6], and this scheme also has been implemented in outbreaks. Despite that, it is essential to take into account that a deficient schedule against HAV may result in a growing number of susceptible adults as reported in the USA, where outbreaks continue to occur as result of lower hepatitis A immunization rates than other vaccines [7].…”