Effectiveness of one and two doses of acellular pertussis vaccines against laboratory-confirmed pertussis requiring hospitalisation in infants: Results of the PERTINENT sentinel surveillance system in six EU/EEA countries, December 2015 - December 2019.

Background: Monitoring effectiveness of pertussis vaccines is necessary to adapt vaccination strategies. PERTINENT, Pertussis in Infants European Network, is an active sentinel surveillance system implemented in 35 hospitals across six EU/EEA countries. We aim to measure pertussis vaccines effectiveness (VE) by dose against hospitalisation in infants aged <1 year.

No association between disease severity and respiratory syncytial virus subtypes RSV-A and RSV-B in hospitalized young children in Norway.

Objective: There is conflicting evidence whether subtypes of Respiratory syncytial virus have different seasonality or are differentially associated with clinical severity. We aimed to explore the associations between disease severity and RSV subtypes RSV-A and RSV-B and to describe the circulation of RSV subtypes pattern by season and age.

Methods: Active prospective hospital surveillance for RSV-A and RSV-B in children <59 months of age was conducted during 2015-2018.

Antibodies against Neisseria meningitidis serogroups A, C, W and Y in serum and saliva of Norwegian adolescents.

Introduction: The incidence of invasive meningococcal disease (IMD) among Norwegian 16-19-year-olds was 1-7/100,000 in the decade before the COVID-19 pandemic, with serogroup Y (MenY) dominance. In contrast to many other European countries, meningococcal vaccines are not part of the national immunisation program (NIP) in Norway. This cross-sectional study aimed to measure the degree of natural immunity against Neisseria meningitidis among adolescents in Norway to evaluate the need for introducing tetravalent meningococcal conjugate vaccine (MCV4) in the NIP.

The burden of hospital-attended influenza in Norwegian children.

Background: Norwegian health authorities do not recommend universal pediatric vaccination against seasonal influenza. We aimed to estimate the incidence of influenza by age and underlying medical conditions in hospitalized Norwegian children aged <18 years.

Methods: Active surveillance for influenza in children <18 years was implemented in five hospitals during 2015-18.

Risk factors associated with severe disease in respiratory syncytial virus infected children under 5 years of age.

Objective: To evaluate risk factors for severe disease in children under 59 months of age hospitalized with respiratory syncytial virus (RSV) infection.

Study Design: We prospectively enrolled 1,096 cases of laboratory confirmed RSV infection during three consecutive RSV seasons in 2015-2018. Potential risk factors for severe disease were retrieved through patient questionnaires and linkage to national health registries.

Long-term exposure to fine particle elemental components and mortality in Europe: Results from six European administrative cohorts within the ELAPSE project.

Evidence for the association between long-term exposure to ambient particulate matter components and mortality from natural causes is sparse and inconsistent. We evaluated this association in six large administrative cohorts in the framework of the Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE) project. We analyzed data from country-wide administrative cohorts in Norway, Denmark, the Netherlands, Belgium, Switzerland and in Rome (Italy).

Household Transmission of SARS-CoV-2: A Prospective Longitudinal Study Showing Higher Viral Load and Increased Transmissibility of the Alpha Variant Compared to Previous Strains.

We studied the secondary attack rate (SAR), risk factors, and precautionary practices of household transmission in a prospective, longitudinal study. We further compared transmission between the Alpha (B.1.

Long term exposure to low level air pollution and mortality in eight European cohorts within the ELAPSE project: pooled analysis.

Objective: To investigate the associations between air pollution and mortality, focusing on associations below current European Union, United States, and World Health Organization standards and guidelines.

Design: Pooled analysis of eight cohorts.

Setting: Multicentre project Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE) in six European countries.

Incidence and severity of pertussis hospitalisations in infants aged less than 1 year in 37 hospitals of six EU/EEA countries, results of PERTINENT sentinel pilot surveillance system, December 2015 to December 2018.

IntroductionPERTINENT is a pilot active surveillance system of infants hospitalised with pertussis in six European Union/European Economic Area countries (37 hospitals, seven sites).AimThis observational study aimed to estimate annual pertussis incidence per site from 2016 to 2018 and respective trends between 2017 and 2018. Pertussis cases were described, including their severity.

Impact of the Rotavirus Vaccination Program in Norway After Four Years With High Coverage.

Background: Use of rotavirus vaccines worldwide since 2006 has led to a significant impact on the burden of rotavirus disease. However, only a third of European countries have introduced rotavirus vaccination in their immunization programs. In October 2014, rotavirus vaccination was introduced for Norwegian infants under strict age restrictions.

Long-term exposure to low-level air pollution and incidence of chronic obstructive pulmonary disease: The ELAPSE project.

Background: Air pollution has been suggested as a risk factor for chronic obstructive pulmonary disease (COPD), but evidence is sparse and inconsistent.

Objectives: We examined the association between long-term exposure to low-level air pollution and COPD incidence.

Methods: Within the 'Effects of Low-Level Air Pollution: A Study in Europe' (ELAPSE) study, we pooled data from three cohorts, from Denmark and Sweden, with information on COPD hospital discharge diagnoses.

Hypoglycaemia was common in acute gastroenteritis in a prospective hospital-based study, but electrolyte imbalances were not.

Aim: Using routine blood sampling in a gastroenteritis diagnostic workup is debatable. This study examined the relationship between the severity of acute gastroenteritis and blood test abnormalities.

Methods: We prospectively enrolled children under five years of age referred for outpatient or inpatient management for gastroenteritis from February 2014 to April 2016.

Lost workdays and healthcare use before and after hospital visits due to rotavirus and other gastroenteritis among young children in Norway.

Background: Cost-effectiveness of rotavirus vaccination is affected by assumptions used in health economic evaluations. To inform such evaluations, we assessed healthcare use before and after hospitalisations due to rotavirus and other acute gastroenteritis (AGE) among children <5years of age in Norway and estimated daycare and work absenteeism.

Methods: We conducted post-discharge interviews with caregivers of 282 children hospitalised with AGE at two hospitals in Norway during April 2014-February 2017.

Burden of Rotavirus Disease in Norway: Using National Registries for Public Health Research.

Background: Norway introduced routine rotavirus immunization for all children born on or after September 1, 2014. We estimated the healthcare burden of all-cause gastroenteritis and rotavirus disease in children <5 years old to establish the prevaccine baseline and support the ongoing immunization program.

Methods: We examined national registry data on gastroenteritis-associated primary care consultations and hospitalizations for 2009-2013 and data on all deaths in children <5 years old reported during 2000-2013.