欧洲疾控中心-流感嗜血杆菌病-2023年度流行病学报告（英）-2025_11页_829kb

Summary of the Annual Epidemiological Report on Haemophilus influenzae Disease (2023)

Core Content

The Annual Epidemiological Report for 2023 provides an overview of invasive Haemophilus influenzae disease (HID) in the EU/EEA, highlighting a continued increase in reported cases and the implications for public health.

Key Facts

• In 2023, 5,234 confirmed cases of invasive Haemophilus influenzae disease were reported in the EU/EEA, marking a continued increase from the 3,983 cases in 2022 and a substantial rise from pandemic-era figures (1,693 in 2021 and 1,838 in 2020).
• The notification rate reached 1.2 cases per 100,000 population, the highest in the past five years, up from 0.9 in 2022 and 0.4 in 2020 and 2021.
• Infants under one year had the highest notification rate at 6.41 per 100,000, followed by those aged 65 years and older at 3.2 per 100,000.
• Serotyping data were available for 60% of cases, with non-capsulated strains accounting for 81% of infections.
• Serotype f was the most frequent capsulated strain, responsible for 6% of cases, followed by serotype b at 5%.

Introduction

Invasive Haemophilus influenzae disease is a serious bacterial infection, with serotype b (Hib) being the most severe, particularly in young children. It can lead to conditions such as meningitis, pneumonia, septicaemia, and epiglottitis. Transmission occurs via respiratory droplets, and the disease is most severe in low-resource settings with a mortality rate up to 40%. The Hib vaccine has been effective in reducing Hib-related meningitis in young children since the 1980s.

Methods

• Data for 2023 were collected from 30 EU/EEA Member States using the EU case definition or compatible definitions.
• The ECDC replaced the TESSy system with EpiPulse Cases in October 2024.
• Vaccination coverage estimates were sourced from the WHO Global Health Observatory.

Epidemiology

• The highest notification rates were in Denmark (2.3), Lithuania (2.1), and Sweden (2.1).
• France, Germany, and Italy accounted for 51% of all confirmed cases.
• The age distribution showed a bimodal pattern, with peaks in infants under one year and individuals aged 65 and over.
• Males had higher notification rates than females across most age groups, with the most pronounced difference in infants under one year (7.3 vs 5.4 per 100,000).

Seasonality and Trend

• The seasonal pattern in 2023 returned to typical winter peaks, with a decline in summer.
• The 12-month moving average continued to rise from mid-2022, reaching a peak in early 2023.
• Case numbers in 2023 remained above the five-year average, but below the maximum seen in previous years.

Serotype Distribution

• Non-capsulated strains were the most common, representing 81% of all cases.
• Serotype f accounted for 6% of cases, while serotype b represented 5%.
• Serotype e had the highest case fatality rate (12.8%), followed by serotype b (8.2%) and non-capsulated strains (7.9%).
• Serotype a had a low rate but showed an increasing trend from 2019.
• The notification rate for unknown serotypes increased to 0.078 per 100,000, the highest in the five-year period.

Clinical Presentation

• Pneumonia was the most common clinical presentation, reported in 638 cases (25%).
• Septicaemia was the second most common, with 606 cases (23%).
• Meningitis was reported in 346 cases (13%), and 56 cases had both meningitis and septicaemia.
• Other presentations included osteomyelitis, septic arthritis, epiglottitis, and cellulitis.
• Clinical information was unknown for 50% of cases.

Outcome

• Case fatality rate (CFR) for known outcomes was 8.6%.
• Infants under one year had the highest CFR at 6.7%, followed by individuals aged 65 and over at 11.5%.
• Serotype e had the highest CFR at 12.8%, with serotype b at 8.2%.
• Unvaccinated individuals accounted for 52% of fatal cases, with 128 deaths (CFR = 10%).

Vaccination Status

• Vaccination status was known for 28% of cases, with 87.3% being unvaccinated.
• Among serotype b cases, 75% had known vaccination status, with 50% unvaccinated and 24% with unknown status.
• The third dose of Hib vaccine was the most common vaccination received among those with known status.

Vaccination Coverage

• Median Hib3 coverage across EU/EEA countries was 94%, with country-specific estimates ranging from 78% to 99%.
• High coverage has been instrumental in maintaining low incidence of serotype b disease.

Discussion

• The case burden in 2023 was over 25% higher than in 2018, indicating a sustained rebound from pandemic suppression.
• Non-capsulated and non-type b strains are increasingly prevalent, suggesting a shift in serotype distribution.
• The decline in serotype b cases reflects the effectiveness of Hib vaccination programs.
• Breakthrough infections in vaccinated individuals highlight the need for continued vaccine effectiveness assessment and flexible immunisation schedules.
• The post-pandemic period has revealed immunity gaps and changes in pathogen dynamics, emphasizing the importance of surveillance and vaccine development.

Public Health Implications

• Maintaining high Hib vaccination coverage among infants and young children is essential.
• Strengthened serotype surveillance and consideration of broader vaccine development are needed to address emerging strains.
• Improved data completeness on clinical presentation, vaccination status, and outcomes is crucial for better epidemiological understanding and targeted interventions.