# P-1511. Pediatric inpatient influenza vaccination before and during the COVID-19 pandemic

## TL;DR

This study found that influenza vaccination screening and administration for hospitalized children dropped during the COVID-19 pandemic compared to before.

## Contribution

The study provides new insights into how the pandemic affected inpatient influenza vaccination practices in pediatric hospitals.

## Key findings

- Influenza vaccination screening decreased from 84.4% pre-pandemic to 73.9% during the pandemic.
- Vaccine administration among eligible patients dropped from 28.2% pre-pandemic to 18.8% during the pandemic.
- Regression analysis showed a significant decline in vaccine receipt across three hospitals after the 2020-21 season.

## Abstract

Annual influenza vaccination is recommended for all individuals >6 months of age during any healthcare seeking opportunity, including hospitalization. While influenza vaccination coverage has declined nationally since the COVID-19 pandemic, the impact of the pandemic on pediatric inpatient influenza vaccination is unknown. Our objective was to assess pediatric influenza vaccine screening and administration during hospitalization before and during/after the COVID-19 pandemic.Table 1.a) Influenza vaccination screening (among hospitalizations) and b) influenza vaccine administrations (among eligible inpatient visits) during the 2018-19 to 2023-24 seasons at Children’s Hospital Colorado, Seattle Children’s Hospital and Lurie Children’s HospitalCHCO- Children’s Hospital Colorado; SCH- Seattle Children’s Hospital; LCH- Lurie Children’s HospitalBreakpoint regression model for inpatient influenza vaccination receipt at a) Children’s Hospital Colorado, b) Seattle Children’s Hospital and c) Lurie Children’s Hospital using the 2020-21 season as the change point (blue line).Plots represent the estimated probability of influenza vaccine receipt over time. P values < 0.05 indicate a significant change in the outcome probabilities over time.

a) Influenza vaccination screening (among hospitalizations) and b) influenza vaccine administrations (among eligible inpatient visits) during the 2018-19 to 2023-24 seasons at Children’s Hospital Colorado, Seattle Children’s Hospital and Lurie Children’s Hospital

CHCO- Children’s Hospital Colorado; SCH- Seattle Children’s Hospital; LCH- Lurie Children’s Hospital

Breakpoint regression model for inpatient influenza vaccination receipt at a) Children’s Hospital Colorado, b) Seattle Children’s Hospital and c) Lurie Children’s Hospital using the 2020-21 season as the change point (blue line).

Plots represent the estimated probability of influenza vaccine receipt over time. P values < 0.05 indicate a significant change in the outcome probabilities over time.

We conducted a retrospective study of children aged 6 months-17 years admitted to a non-intensive care unit at Children’s Hospital Colorado, Seattle Children’s Hospital, or Lurie Children’s Hospital during the 2018-19 through 2023-24 seasons. We compared inpatient influenza vaccine screening and administration between the pre-pandemic (2018-2020) and pandemic (2020-2024) periods. We also assessed the change in rates over time using segmented modelling via breakpoint regression.

During the study period, 70,306 children were admitted to the three hospitals representing 94,719 hospitalizations. The median age of individuals was 7.1 years (IQR 2.4-13.4), 52.2% were male, 56.6% were White, 10.4% were Black, 5.4% were Asian, 35% were Hispanic. Most children were admitted to a medical unit (56.5%), followed by a surgical unit (19.7%). Overall, 25,571 (84.4%) were screened for influenza vaccination status during the pre-pandemic period, which declined during the pandemic period to 47,631 (73.9%). Among vaccine-eligible patients who were screened, 2,718 (28.2%) received a dose during the pre-pandemic period, which declined to 4,181(18.8%) during the pandemic period. Influenza vaccine administration was highest during the 2019-20 season. These screening and administration rates differed between the pre-pandemic and pandemic periods (Table 1). Regression modeling with segmented relationships demonstrated a decline in vaccine receipt across all three sites (Figure 1).

There was a decline in influenza screening and vaccine administrations during the COVID-19 pandemic. These trends mirror outpatient findings and require tailored strategies to promote vaccination.

Ravi Jhaveri, MD, AstraZeneca: Advisor/Consultant|Gilead: Advisor/Consultant|GSK: Grant/Research Support|PIDS: editorial stipend-JPIDS|Sanofi: Advisor/Consultant|Seqirus: Advisor/Consultant|UptoDate: royalties