Background: The availability of self- or caregiver-administered nasal spray live attenuated influenza vaccine (LAIV) raises the potential for increased influenza vaccine uptake and increased vaccine effectiveness (VE) via mucosal immunity. Direct and indirect benefits of increased uptake among school-age children (decreased influenza cases and hospitalizations) may be realized across the age spectrum. We used an agent-based model, the Framework for Reproducing Epidemiological Dynamics (FRED) to determine the extent to which increased vaccination of children might affect overall influenza epidemiology. Methods: FRED uses a population based on the US census and accounts for individual characteristics to estimate the effect of changes in parameters including vaccine uptake on outcomes. We modeled increases in vaccine uptake and VE among school-age children 5-17 years on influenza cases and hospitalizations by age group. Results: Increasing vaccination rates in school-aged children by 5%-15% decreased their symptomatic influenza cases by 3.2%-10.9%, and over all age groups by 3.3%-11.6%, corresponding to an estimated annual reduction in cases among school-age children of 522,867-1,810,170 and 1,394,687-4,945,952 overall. Fewer days of missed school by children and work by caregivers could offset those required to increase vaccination coverage. Annual U.S. hospitalizations could decrease by as much as 49,977, with the greatest impact (23,258) in those ages 65 years and over. If childhood influenza VE increased only 5%, the attendant improvement in cases would exceed that of a 5%-15% increase in vaccination coverage. Conclusion: The opportunity to increase vaccination coverage in school-age children using LAIV can have a positive impact across all ages.

Background: Acute respiratory infections (ARIs) result in millions of illnesses and hundreds of thousands of hospitalizations annually in the US. The responsible viruses include influenza, parainfluenza, human metapneumovirus, coronaviruses, respiratory syncytial virus (RSV), and human rhinoviruses. This study estimated the population-based hospitalization burden of 18 respiratory viruses (RV) over 4 years, from 7/1/2015 to 6/30/2019 among adults ≥18 years of age for Allegheny County (Pittsburgh), Pennsylvania. Methods: We used population-based statewide hospital discharge data, health system electronic medical record (EMR) data for RV tests, census data, and a published method to calculate burden. Results: Among 26,211 eligible RV tests, 67.6% were negative for any virus. The viruses detected were rhinovirus/enterovirus (2,552; 30.1%), influenza A (2,299; 27.1%), RSV (1,082; 12.7%), human metapneumovirus (832; 9.8%), parainfluenza (601; 7.1%), influenza B (565; 6.7%), non-SARS-CoV-2 coronavirus (420; 4.9% 1.5 years of data available), and adenovirus (136; 1.6%). Most tests were among female (58%) and white (71%) patients with 60% of patients ≥65 years, 24% 50-64 years and 16% 18-49 years. The annual burden, ranged from 137-174/100,000 population for rhinovirus/enterovirus; 99-182/100,000 for influenza A; 56-81/100,000 for RSV. Among adults <65 years, rhinovirus/enterovirus hospitalization burden was higher than influenza A; whereas the reverse was true for adults ≥65 years. RV hospitalization burden increased with increasing age. Conclusions: These virus-specific ARI population-based hospital burden estimates showed significant non-influenza burden. These estimates can serve as the basis for several areas of research that are essential for setting funding priorities and guiding public health policy.