Peer-reviewed article
Seroprevalence and predictors of measles antibody positivity among children aged 18-24 months in Pakistan: a national survey.
Najma Javed, Maimoona Sabir, Mohammad Arif Nadeem Saqib, Sidra Abbas ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This national survey in Pakistan measured how many vaccinated children aged 18-24 months developed protective antibodies against measles. Among 3,596 vaccinated children, only 65% developed measles antibodies despite high vaccine coverage rates. The study found that seropositivity was higher in rural areas and among children vaccinated by mobile health workers, and that the first vaccine dose was particularly important for developing antibodies.
Key points
- 65% of vaccinated children were seropositive for measles IgG antibodies, indicating suboptimal seroconversion
- 90% of children received the first measles dose (MCV1) and 78% received the second dose (MCV2), showing high vaccine coverage
- Children vaccinated by mobile vaccinators had higher seroprevalence compared to other vaccination settings
- Seropositivity was significantly associated with vaccination source, documentation status, rural residence, place of delivery, and history of prior measles infection
- Measles cases in Pakistan doubled between 2019 and 2020 despite improved vaccine coverage
Limitations
The survey only measured antibody presence in children 18-24 months old and cannot determine how long protective immunity lasts or explain why seroconversion was suboptimal. The study does not describe the specific quality or training differences between vaccination settings that might account for variations in seroprevalence.
Abstract
BACKGROUND: Measles remain a leading cause of childhood morbidity and mortality. Despite improved vaccine coverage, the number of laboratory-confirmed measles cases in Pakistan doubled between 2019 and 2020. Although an effective vaccine has been available for decades, sporadic outbreaks continue to occur. This study aimed to determine the seroprevalence of measles IgG antibodies among vaccinated children in Pakistan. METHODS: A cross-sectional survey was conducted between April 2019 and October 2020 in seven districts across Pakistan. Using a multistage sampling technique, healthy children aged 18-24 months with a history of measles vaccination were randomly enrolled after obtaining informed written consent. Venous blood samples (3 cc) were collected and tested for measles IgG antibodies using ELISA. RESULTS: Among 3596 vaccinated children, 65% were seropositive for measles IgG antibodies. Vaccine coverage was high, with 90% receiving the first measles dose (MCV1) administered at 9 months of age and 78% the second dose (MCV2) administered at 15 months. Seropositivity was significantly associated with vaccination source, documentation status, rural residence, place of delivery, and history of prior measles infection. Higher seroprevalence was observed among children vaccinated by mobile vaccinators compared to other vaccination settings. CONCLUSION: Seroconversion among vaccinated children was suboptimal, with only 65% achieving protective antibody levels. The first dose of measles vaccine appeared particularly important for antibody development. Strengthening vaccination services, ensuring delivery through trained vaccinators, and conducting regular seroprevalence surveys are essential for evidence-based policies to achieve measles elimination in Pakistan.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
- Intervention
- Measles vaccination (MCV1 at 9 months and MCV2 at 15 months) provided through various vaccination settings including mobile vaccinators
- Population
- 3,596 healthy children aged 18-24 months with documented measles vaccination history across seven districts in Pakistan
Key finding
65% of vaccinated children achieved seropositive status for measles IgG antibodies