Abstract:Respiratory syncytial virus (RSV) is a major public health problem that has undergone significant changes in recent years. First of all, it has become easier to diagnose with highly reliable and rapidly available confirmatory tests. This has led to a better understanding of its epidemiology and RSV has gone from being a disease of the pediatric age group, severe only in infants and immunosuppressed children, to being a common disease in people of all ages, particularly important in patients of advanced age or … Show more
IntroductionRespiratory syncytial virus (RSV) infection is one of the main causes of morbidity and mortality from lower respiratory tract infections in children under 5 years of age worldwide. Given that, the objective of this study was estimate the effectiveness of nirsevimab (a single-dose, long-acting, human recombinant monoclonal antibody against RSV) over time for the prevention of respiratory episodes treated at different levels of care.MethodsA prospective and dynamic population-based cohort study was performed including infants born between April 1 and December 31, 2023, in the Madrid region who resided there during the follow-up period from October 1, 2023, to February 29, 2024. Infants were considered immunized from the day after receiving one dose (50 or 100 mg) of nirsevimab or nonimmunized individuals if they did not receive any dose.ResultsThere were 4,100 episodes of primary care, 1,954 hospital emergencies, and 509 admissions, 82 of which required intensive care in the 33,859 participants analyzed. The adjusted effectiveness of nirsevimab in preventing hospitalization due to RSV infection was 93.6% (95% CI: 89.7 to 96.1) at 30 days and 87.6% (95% CI: 67.7 to 95.3) at 150 days. The number needed to treat to prevent one hospitalization were 314.19 (95% CI: 306.22 to 327.99) at 30 days and 24.30 (95% CI: 22.31 to 31.61) at 150 days. The adjusted effectiveness of nirsevimab in avoiding admission to an intensive care unit was 94.4% (95% CI: 87.3 to 97.5) at 30 days and 92.1% (95% CI: 64.0 to 98.3) at 90 days. The adjusted effectiveness of nirsevimab for avoiding primary care consultations and hospital emergency visits was lower.DiscussionImmunization with nirsevimab is an effective measure for reducing the burden of care related to RSV at all levels of care albeit it decreases throughout follow-up. At 150 days it remained high for preventing hospital admissions. Other articles already published have also demonstrated high effectiveness although with preliminary results, short follow-up periods and wide confidence intervals. None have detected a decrease in effectiveness over time. These results can be quite useful in individual infant prevention and in the design of immunization campaigns.
The COVID-19 pandemic has impacted the epidemiology of other infectious diseases. In particular, the respiratory syncytial (RS) virus infects almost all children during their first or second year of life. However, during the COVID-19 pandemic, many restrictions were enforced that isolated children from other children. Therefore, we hypothesized that the clinical features of RS virus infection were altered and conducted a study to evaluate these changes. This observational study included children below the age of six years who were admitted to the Tokyo Metropolitan Toshima Hospital. Their clinicodemographic data were extracted from medical records. The 369 children eligible for the study were assigned to three groups: “pre-pandemic” (group 1, n = 253); “during pandemic” (group 2, n = 77), and “post-pandemic” (group 3, n = 39). Logistic regression analysis revealed that compared to group 1, the odds ratio (OR) for oxygen use was significantly higher in groups 2 (OR 1.85. 95% confidence interval [CI] 1.06–3.23; p < 0.05) and 3 (OR 3.36, 95% CI 1.59–7.12; p < 0.01), and the use of mechanical ventilation was significantly higher in group 3 (OR 4.89, 95% CI 1.71–13.94; p < 0.01). This study highlights changes in the clinical features of RS virus infection during and after the COVID-19 pandemic.
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