Abstract
Background: With its rapid introduction in 2009, concerns about the safety of the H1N1 vaccines have been raised. Data were especially limited on the pediatric safety of H1N1 vaccine in Saudi Arabia.
Objectives: The objectives of this study were to investigate the safety of the H1N1 vaccine (Pandemrix (R)) in children and examine the feasibility of obtaining information on possibly associated adverse reactions using mobile telephone contact with child caregivers.
Methods: A cohort study was conducted in Riyadh, Saudi Arabia. Patients were included if they were aged between 6 and 18 years and had received one dose of the H1N1 vaccine. A control group involved children from the same school system who had not received the vaccine. Six months following vaccination, a clinical pharmacist called the caregiver of the child to ask about hospitalization, emergency room visits and events related to H1N1 vaccine administration using a standardized questionnaire.
Results: Caregivers of 372 school-age children were contacted. The response rate was 97% (n=359). A total of 169 children who received at least one dose of the H1N1 vaccine were compared with 190 children in the control group who had not received the vaccine. Controlling for age, sex, education and use of medications, the odds ratio (OR) of hospitalization or emergency room visits for children within the 6 months after vaccination relative to the unvaccinated children was 1.25 (95% CI 0.47, 3.35). The risk of influenza-like symptoms was significantly reduced in vaccinated children compared with unvaccinated children (OR 0.63; 95% CI 0.41, 0.99).
Conclusion: School-age children in Saudi Arabia who received the H1N1 vaccine did not have an increased risk of hospitalization or emergency room visits. Larger studies are needed to confirm these results. Proactive pharmacovigilance is important in assessing the safety of vaccines and other medications. It is feasible to collect information on adverse drug reactions using mobile telephones, a method that can be of benefit in both developed and developing countries.