Exploring the effect of clinical case definitions on influenza vaccine effectiveness estimation at primary care level: Results from the end-of-season 2022-23 VEBIS multicentre study in Europe.

BACKGROUND: Within influenza vaccine effectiveness (VE) studies at primary care level with a laboratory-confirmed outcome, clinical case definitions for recruitment of patients can vary. We used the 2022-23 VEBIS primary care European multicentre study end-of-season data to evaluate whether the clinical case definition affected IVE estimates. METHODS: We estimated VE using a multicentre test-negative case-control design. We measured VE against any influenza and influenza (sub)types, by age group (0-14, 15-64, ≥65 years) and by influenza vaccine target group, using logistic regression. We estimated IVE among patients meeting the European Union (EU) acute respiratory infection (ARI) case definition and among those meeting the EU influenza-like illness (ILI) case definition, including only sites providing information on specific symptoms and recruiting patients using an ARI case definition (as the EU ILI case definition is a subset of the EU ARI one). RESULTS: We included 24 319 patients meeting the EU ARI case definition, of whom 21 804 patients (90 %) meet the EU ILI case definition, for the overall pooled VE analysis against any influenza. The overall and influenza (sub)type-specific VE varied by ≤2 % between EU ILI and EU ARI populations. DISCUSSION: Among all analyses, we found similar VE estimates between the EU ILI and EU ARI populations, with few (10%) additional non-ILI ARI patients recruited. These results indicate that VE in the 2022-23 influenza season was not affected by use of a different clinical case definition for recruitment, although we recommend investigating whether this holds true for next seasons.

An Increasing Scabies Incidence in Croatia: A Call for Coordinated Action Among Dermatologists, Physicians and Epidemiologists.

INTRODUCTION: The aim of our study was to examine the scabies incidence in the Croatian population and to analyse potential related factors. METHODS: This mixed ecological study is based on a retrospective medical record review. National data from communicable disease reports was sourced and analysed for an 11-year period (2007-2017), with more focus on the period 2014-2017. Descriptive statistics were used to calculate trends. Differences between the groups were studied using Chi-square test and Kendall's tau (τ) correlation coefficient. Levels of significance were set at p<0.05 or p<0.01. RESULTS: From 2007 to 2017, scabies infestation in Croatia increased by 6-fold, particularly affecting children and young adults (19 years or younger). In the period 2014-2017, border counties which are part of migration flows were the counties with the highest average scabies incidences. A linear trend of increase in the number of tourists, immigrants and scabies infestations was noted on the national level for the analysed period, although a significant association was not observed. Regarding outbreaks of scabies within institutions, more than 80% of outbreaks occurred in institutions for adults. In the capital, Zagreb, the crude incidence rate increased 3-fold between 2014 and 2017. CONCLUSIONS: The increased incidence of scabies, large disparities between counties, and prolonged outbreaks within families due to under-recognition and misdiagnoses points to a need for increased awareness among health practitioners. To the best of our knowledge, this is the first recent epidemiologic analysis on this topic, not only in Croatia but within the wider geographic region as well.

Effectiveness of influenza vaccine against influenza A in Europe in seasons of different A(H1N1)pdm09 and the same A(H3N2) vaccine components (2016-17 and 2017-18).

INTRODUCTION: Influenza A(H3N2) viruses predominated in Europe in 2016-17. In 2017-18 A(H3N2) and A(H1N1)pdm09 viruses co-circulated. The A(H3N2) vaccine component was the same in both seasons; while the A(H1N1)pdm09 component changed in 2017-18. In both seasons, vaccine seed A(H3N2) viruses developed adaptations/alterations during propagation in eggs, impacting antigenicity. METHODS: We used the test-negative design in a multicentre primary care case-control study in 12 European countries to measure 2016-17 and 2017-18 influenza vaccine effectiveness (VE) against laboratory-confirmed influenza A(H1N1)pdm09 and A(H3N2) overall and by age group. RESULTS: During the 2017-18 season, the overall VE against influenza A(H1N1)pdm09 was 59% (95% CI: 47-69). Among those aged 0-14, 15-64 and ≥65 years, VE against A(H1N1)pdm09 was 64% (95% CI: 37-79), 50% (95% CI: 28-66) and 66% (95% CI: 42-80), respectively. Overall VE against influenza A(H3N2) was 28% (95% CI: 17-38) in 2016-17 and 13% (95% CI: -15 to 34) in 2017-18. Among 0-14-year-olds VE against A(H3N2) was 28% (95%CI: -10 to 53) and 29% (95% CI: -87 to 73), among 15-64-year-olds 34% (95% CI: 18-46) and 33% (95% CI: -3 to 56) and among those aged ≥65 years 15% (95% CI: -10 to 34) and -9% (95% CI: -74 to 32) in 2016-17 and 2017-18, respectively. CONCLUSIONS: Our study suggests the new A(H1N1)pdm09 vaccine component conferred good protection against circulating strains, while VE against A(H3N2) was <35% in 2016-17 and 2017-18. The egg propagation derived antigenic mismatch of the vaccine seed virus with circulating strains may have contributed to this low effectiveness. A(H3N2) seed viruses for vaccines in subsequent seasons may be subject to the same adaptations; in years with lower than expected VE, recommendations of preventive measures other than vaccination should be given in a timely manner.

Improving preparedness to respond to cross-border hepatitis A outbreaks in the European Union/European Economic Area: towards comparable sequencing of hepatitis A virus.

IntroductionSequence-based typing of hepatitis A virus (HAV) is important for outbreak detection, investigation and surveillance. In 2013, sequencing was central to resolving a large European Union (EU)-wide outbreak related to frozen berries. However, as the sequenced HAV genome regions were only partly comparable between countries, results were not always conclusive.AimThe objective was to gather information on HAV surveillance and sequencing in EU/European Economic Area (EEA) countries to find ways to harmonise their procedures, for improvement of cross-border outbreak responses.MethodsIn 2014, the European Centre for Disease Prevention and Control (ECDC) conducted a survey on HAV surveillance practices in EU/EEA countries. The survey enquired whether a referral system for confirming primary diagnostics of hepatitis A existed as well as a central collection/storage of hepatitis A cases' samples for typing. Questions on HAV sequencing procedures were also asked. Based on the results, an expert consultation proposed harmonised procedures for cross-border outbreak response, in particular regarding sequencing. In 2016, a follow-up survey assessed uptake of suggested methods.ResultsOf 31 EU/EEA countries, 23 (2014) and 27 (2016) participated. Numbers of countries with central collection and storage of HAV positive samples and of those performing sequencing increased from 12 to 15 and 12 to 14 respectively in 2016, with all countries typing an overlapping fragment of 218 nt. However, variation existed in the sequenced genomic regions and their lengths.ConclusionsWhile HAV sequences in EU/EEA countries are comparable for surveillance, collaboration in sharing and comparing these can be further strengthened.

[Epidemiology of viral hepatitis]. / Epidemiologija virusnih hepatitisa.

Understanding the country-specific epidemiology of disease, which may vary greatly among countries, is crucial for identifying the most appropriate preventive and control measures. An overview of the local epidemiology of viral hepatitis in Croatia is given in this paper. The overall prevalence of hepatitis B in Croatia is low (less than 2% HBsAg carriers in the general population). Hepatitis B incidence and prevalence began to decline significantly following the introduction of universal hepatitis B vaccination in 1999. Information on HBsAg seroprevalence is derived from routine testing of certain subpopulations (pregnant women, blood donors) and seroprevalence studies mostly targeted at high-risk populations. Universal childhood vaccination against hepatitis B remains the main preventive measure. We recommend testing for immunity one to two months after the third dose of hepatitis B vaccine for health-care workers. The incidence and prevalence of hepatitis C have also been declining in the general population. The main preventive measures are ensuring safety of blood products, prevention of drug abuse, and harm reduction programs for intravenous drug users. Hepatitis A incidence has declined dramatically since fifty years ago, when thousands of cases were reported annually. In the last five years, an average of twenty cases have been reported per year. The reduction of hepatitis A is a consequence of improved personal and community hygiene and sanitation. Hepatitis D has not been reported in Croatia. The risk of hepatitis D will get to be even smaller as the proportion of population vaccinated against hepatitis B builds up. Hepatitis E is reported only sporadically in Croatia, mostly in persons occupationally in contact with pigs and in travelers to endemic countries. In conclusion, Croatia is a low prevalence country for hepatitides A, B and C. Hepatitis D has not been reported to occur in Croatia and there are only sporadic cases of hepatitis E. Since hepatitis A is a rare disease occurring sporadically, which is a consequence of improved sanitation and hygiene, hepatitides B and C are the main causes of viral hepatitis in Croatia. The introduction of universal mandatory hepatitis B vaccination of schoolchildren in 1999 resulted in a decrease in the incidence of hepatitis B, which is most pronounced in adolescents and young adults, and further decrease in the incidence and prevalence is expected as the pool of susceptible individuals decreases through vaccination. The incidence of hepatitis C is decreasing as well. In spite of a relatively favorable epidemiological situation, hepatitis B and C are still a significant public health burden with an estimated 25,000 persons chronically infected with HBV and about 40,000 persons chronically infected with HCV in Croatia.