# Impact of COVID‐19 on the Prevalence and Drug Resistance of Haemophilus influenzae in Shandong Province: A Multicenter Retrospective Study

## TL;DR

This study shows how the COVID-19 pandemic affected the spread and drug resistance of Haemophilus influenzae in Shandong Province.

## Contribution

The study reveals how pandemic measures changed the epidemiology and resistance patterns of H. influenzae in a specific region.

## Key findings

- The isolation rate of H. influenzae dropped significantly during the pandemic, reaching a low in 2020.
- Resistance to ampicillin increased from 76.2% before the pandemic to 89.2% after it.
- β-lactamase positivity rates rose annually, while β-lactamase-negative ampicillin-resistant strains declined.

## Abstract

The COVID‐19 pandemic has profoundly impacted global public health, particularly the epidemiology and antimicrobial resistance patterns of pathogens. This study aimed to assess the influence of COVID‐19 on the isolation rates of Haemophilus influenzae in Shandong Province, providing data support for empirical precision treatment in clinical practice and offering insights for future pandemic response strategies.

A retrospective analysis was conducted on laboratory results and clinical records of H. influenzae reported by the Shandong Pediatric Antimicrobial Resistance Surveillance System from 2017 to 2023. A total of 39,043 isolates were included to analyze epidemiological trends and resistance patterns.

The isolation rate of H. influenzae significantly declined during the COVID‐19 period, reaching its lowest point in 2020, followed by a rebound in 2023. Male patients accounted for a higher proportion of cases (63.4%), and infections exhibited seasonal patterns, with the peak delayed by approximately 3 months compared to the pre‐pandemic period. The resistance rates to ampicillin were 76.2%, 85%, and 89.2% before, during, and after the pandemic, respectively. The β‐lactamase positivity rate increased annually, while the detection rate of β‐lactamase‐negative ampicillin‐resistant strains declined.

The COVID‐19 pandemic significantly altered the epidemiological characteristics and resistance patterns of H. influenzae in Shandong Province. Continuous and dynamic surveillance of its trends and resistance profiles is crucial for guiding clinical treatment and infection control. These findings also provide strategic insights for global preparedness against future pandemics.