Measles immunity in a large urban center in northeastern Brazil: an assessment using the Plaque Reduction Neutralization Test and Enzyme-Linked Immunosorbent Assay
1
Institute of Collective Health, Federal University of Bahia, Bahia, Brazil
2
René Rachou Institute, Oswaldo Cruz Foundation, Minas Gerais, Brazil
3
Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
Popul. Med. 2026;8(Supplement Supplement 1):
ABSTRACT
INTRODUCTION:
This study aimed to characterize the measles immunity profile, describe antibody dynamics, and estimate the proportion of neutralizing antibodies in the studied population.
METHODS:
A seroprevalence study of neutralizing antibodies was conducted among 671 participants from a measles immunoglobulin G (IgG) seroprevalence survey carried out in 2024 in a population sample aged over 2 years residing in 30 Sentinel Areas in Salvador, Bahia, Brazil. A structured questionnaire collected sociodemographic data, vaccination history, and disease occurrence, and venous blood samples (5 mL) were obtained for serological analysis. Descriptive analyses estimated positivity by the Plaque Reduction Neutralization Test (PRNT) and the Enzyme-Linked Immunosorbent Assay (ELISA) according to age group. Associations were assessed by the chi-square test, agreement between tests by Cohen’s Kappa coefficient, and logistic regression adjusted for sex and age assessed factors associated with PRNT positivity. Results were expressed as odds ratios (OR) with 95% confidence intervals (95% CI).
RESULTS:
Of the 671 participants, 60.8% were female and 38.3% were aged ≥50 years. Most had incomplete elementary education and family income ≤2 minimum wages. Approximately 54.6% reported no prior measles infection, while 30% reported previous disease. Although 79.1% reported measles vaccination, only 8.3% presented vaccination records, of which 72.7% documented the second dose. Seroprevalence was 91.4% by PRNT and 85.4% by ELISA, with observed agreement of 86.3% (Kappa = 0.34; p < 0.001). The highest PRNT positivity occurred among individuals aged 10–19 years and ≥50 years, whereas the highest seronegativity was observed among those aged 20–29 years (23.4%). In adjusted logistic regression, individuals aged 5–19 years showed lower odds of PRNT positivity compared with those aged 2–4 years, with no significant difference between sexes.
CONCLUSIONS:
The study identified vulnerabilities in measles protection, particularly among young adults, and may support the Brazilian National Immunization Program in strengthening measles control strategies.
This study aimed to characterize the measles immunity profile, describe antibody dynamics, and estimate the proportion of neutralizing antibodies in the studied population.
METHODS:
A seroprevalence study of neutralizing antibodies was conducted among 671 participants from a measles immunoglobulin G (IgG) seroprevalence survey carried out in 2024 in a population sample aged over 2 years residing in 30 Sentinel Areas in Salvador, Bahia, Brazil. A structured questionnaire collected sociodemographic data, vaccination history, and disease occurrence, and venous blood samples (5 mL) were obtained for serological analysis. Descriptive analyses estimated positivity by the Plaque Reduction Neutralization Test (PRNT) and the Enzyme-Linked Immunosorbent Assay (ELISA) according to age group. Associations were assessed by the chi-square test, agreement between tests by Cohen’s Kappa coefficient, and logistic regression adjusted for sex and age assessed factors associated with PRNT positivity. Results were expressed as odds ratios (OR) with 95% confidence intervals (95% CI).
RESULTS:
Of the 671 participants, 60.8% were female and 38.3% were aged ≥50 years. Most had incomplete elementary education and family income ≤2 minimum wages. Approximately 54.6% reported no prior measles infection, while 30% reported previous disease. Although 79.1% reported measles vaccination, only 8.3% presented vaccination records, of which 72.7% documented the second dose. Seroprevalence was 91.4% by PRNT and 85.4% by ELISA, with observed agreement of 86.3% (Kappa = 0.34; p < 0.001). The highest PRNT positivity occurred among individuals aged 10–19 years and ≥50 years, whereas the highest seronegativity was observed among those aged 20–29 years (23.4%). In adjusted logistic regression, individuals aged 5–19 years showed lower odds of PRNT positivity compared with those aged 2–4 years, with no significant difference between sexes.
CONCLUSIONS:
The study identified vulnerabilities in measles protection, particularly among young adults, and may support the Brazilian National Immunization Program in strengthening measles control strategies.
| eISSN: | 2654-1459 |
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