The influenza landscape and vaccination coverage in older adults during the SARS-Cov-2 pandemic: data from Several European Countries and Israel.

INTRODUCTION: The Raise Awareness of Influenza Strategies in Europe (RAISE) group gathered information about the healthcare burden of influenza (hospitalizations, intensive care unit [ICU] admissions, and excess deaths), surveillance systems, and the vaccine coverage rate (VCR) in older adults in 18 European countries and Israel. AREAS COVERED: Published medical literature and official medical documentation on the influenza disease burden in the participating countries were reviewed from 2010/11 until the 2022/23 influenza seasons. Information on the framework for monitoring the disease burden and the provision for ensuring older adults had access to vaccination in their respective countries was provided. Data on influenza VCR in older adults were collected for the 2019/20 to 2022/23 influenza seasons. Data are reported descriptively. EXPERT OPINION: Influenza presents a significant healthcare burden in older adults. Reporting outcomes across participating countries is heterogeneous, highlighting the need for standardized approaches. Although older adults receive free influenza vaccination, vaccine uptake is highly variable among countries. Moreover, hospitalization rates remain high even in countries reporting a high VCR. Increased awareness and education on the burden of disease and the broader use of improved influenza vaccines for older adults may help reduce the disease burden on this population.

Norovirus strains among children aged 0-18 years hospitalized with acute gastroenteritis in Estonia 2015-2016.

Norovirus (NoV) is the leading cause of acute gastroenteritis (AGE) in many countries that have introduced universal rotavirus mass vaccination. This is the first study to report data on NoV strains in Estonia. We recruited 2249 children aged 0-18 years hospitalized for AGE in Estonian hospitals from February 1, 2015 to August 31, 2016. Norovirus gastroenteritis (NoVGE) was diagnosed in 14.5% (n = 325) cases. Stool sample for RNA extraction and genotyping was available in 86% (n = 280) of NoVGE cases (2015, n = 91; 2016, n = 189). Dominant capsid types detected in 75% (n = 210) samples were, GII.4 (63.8%, n = 134), GII.3 (15.2%, n = 32), GII.17 (6.7%, n = 14), and GII.6 (5.2%, n = 11). Prevailing RNA polymerase types found in 77% (n = 215) samples were GII.P31 (51.1%, n = 110), GII.P21 (17.7%, n = 38), GII.P4 (11.2%, n = 24), and GII.P7 (6.5%, n = 14). Both regions were typeable for 67% (n = 189) of samples. Most prevalent strains were GII.4Sydney_2012[P31] (48.7%, n = 92), GII.3[P21] (15.3%, n = 29), GII.4Sydney_2012[P4] (5.8%, n = 11) and GII.17[P17] (5.8%, n = 11). Simpson's diversity index showed a significant difference between the age groups 1-4 and 5-9 years: D 0.64 (95% confidence interval [CI]: 0.55-0.73) versus 0.83 (95% CI: 0.81-0.86), respectively (p = 0.03). An accurate understanding of NoV strain diversity is important for control and preventive measures, especially in the postrotavirus vaccine era.

Rotavirus Strain Surveillance in Estonia After Introduction of Rotavirus Universal Mass Vaccination.

BACKGROUND: Estonia implemented the rotavirus (RV) vaccine into its national immunization program in July 2014. We aimed to determine circulating RV genotypes and the clinical profile by genotypes from February 1, 2015, to August 30, 2016, among children 0-18 years hospitalized due to rotavirus gastroenteritis (RVGE). METHODS: During an observational study in 7 Estonian hospitals, we determined the RV genotypes in stool samples of RVGE patients who met predetermined criteria. Shannon's diversity index (H´) and Simpson's index (D) was used to evaluate genotype diversity by season and age and to compare prevaccine period data (2007-2008) for children 0-4 years of age (n = 77) to corresponding data from the postvaccine period (2015-2016, n = 346). The Vesikari Clinical Severity Scoring System was used for clinical profile evaluation. RESULTS: Stool samples of 479 RVGE patients were genotyped. Seventy-seven percent of RVGE infections were caused by G4P[8] (n = 150, 31%), G1P[8] (n = 100, 21%), G9P[8] (n = 79, 16%), G2P[4] (n = 23, 5%), G4P[4] (n = 17, 4%). The prevailing genotypes varied seasonally. Diversity increased during the postvaccine period among age groups 0-4: H´1.42 (95% CI: 1.2-1.7) in the prevaccine era versus 1.8 (95% CI: 1.7-2) in the postvaccine era (P = 0.008), and D 0.6 (95% CI: 0.5-0.7) versus 0.78 (0.75-0.80) (P = 0.01), respectively. The off-season period presented higher diversity compared with in-seasons. G2P[8], G1P[8], G4P[4], G9P[8], and G8P[8] presented with a different clinical profile compared with others. CONCLUSION: Since the introduction of universal mass vaccination in Estonia, the circulating RV genotypes have changed compared with those reported in the prevaccine era. Our study adds to knowledge about RV genotype distribution in Europe and expected dynamics after RV universal mass vaccination and provides insight on the clinical profile of prevailing genotypes.

Acute gastroenteritis hospitalizations after implementation of universal mass vaccination against rotavirus.

BACKGROUND: Estonia implemented rotavirus universal mass vaccination (RV UMV) in July 2014. We aimed to describe changes in acute gastroenteritis (AGE) hospitalization during RV seasons before (2007-2013) and after (2015-2018) RV UMV and compare patient profile of hospitalized AGE patients aged 0-18 years during first two consecutive RV seasons 2015 vs 2016. METHODS: We described AGE hospitalization patterns pre-and post-vaccine era using Estonian Health Insurance Fund (HIF) database. During a two-year observational multicenter study in seven Estonian hospitals from 01st of February 2015 to 30th August 2016 we assessed patient profile of all patients who met pre-determined AGE criteria. RESULTS: In post-vaccine era AGE hospitalization rate decreased from 10 to 8 per 1000 population (RR 0.81, 95% CI 0.79-0.83) compared to pre-vaccine era. Decreased RV seasonal activity, 81% (95% CI 77-84) and 55% (95% CI 52-58) reduction of rotavirus gastroenteritis (RVGE) hospitalization among age groups <1 and 1-4, respectively and upsurge of norovirus gastroenteritis (NoVGE) hospitalizations (RR = 1.8; 95% CI 1.6-1.9) was seen. In the multicenter observational study, among 2249 AGE patients hospitalized median age of RVGE patients increased from 2 to 3 years (p < 0.01) and duration of hospital stay decreased among RVGE, NoVGE and other GE patients during two consecutive RV seasons. According to Vesikari Clinical Severity Scoring System statistically significant change of severity score distribution in two RV seasons was seen (p < 0.001) with trend towards less severe AGE hospitalizations; 82.5% vs 70.5% severe cases in 2015 vs 2016, respectively. CONCLUSION: RV UMV lead to immediate and sustainable reduction of hospitalizations due to RVGE in children aged <4 years and reduction of overall AGE accompanied with the decrease in the severity of hospitalized children.