Nationwide upsurge in invasive disease in the context of longitudinal surveillance of carriage and invasive 2009-2023, the Netherlands: a molecular epidemiological study.

Since 2022, many countries have reported an upsurge in invasive group A streptococcal (iGAS) infections. We explored whether changes in carriage rates or emergence of strains with potentially altered virulence, such as 1 variants M1 and M1, contributed to the 2022/2023 surge in the Netherlands. We determined (sub)type distribution for 2,698 invasive and 351 .

Informed consent for national registration of COVID-19 vaccination caused information bias of vaccine effectiveness estimates mostly in older adults: a bias correction study.

Objectives: Registration in the Dutch national COVID-19 vaccination register requires consent from the vaccinee. This causes misclassification of nonconsenting vaccinated persons as being unvaccinated. We quantified and corrected the resulting information bias in vaccine effectiveness (VE) estimates.

COVID-19 vaccination-induced antibody responses and waning by age and comorbidity status in a large population-based prospective cohort study.

Background: Information on the magnitude and duration of antibody levels after COVID-19 vaccination in different groups may be useful for prioritizing of additional vaccinations.

Methods: Serum samples were collected every six months in a prospective cohort study among adults in the Netherlands. Geometric mean concentrations (GMCs) of antibodies against the receptor binding domain of the SARS-CoV-2 spike protein were calculated after the primary series, first, and second booster vaccinations.

Effectiveness of XBB.1.5 Monovalent COVID-19 Vaccines During a Period of XBB.1.5 Dominance in EU/EEA Countries, October to November 2023: A VEBIS-EHR Network Study.

Using a common protocol across seven countries in the European Union/European Economic Area, we estimated XBB.1.5 monovalent vaccine effectiveness (VE) against COVID-19 hospitalisation and death in booster-eligible ≥ 65-year-olds, during October-November 2023.

Effectiveness of Omicron XBB.1.5 vaccine against infection with SARS-CoV-2 Omicron XBB and JN.1 variants, prospective cohort study, the Netherlands, October 2023 to January 2024.

We estimated vaccine effectiveness (VE) of SARS-CoV-2 Omicron XBB.1.5 vaccination against self-reported infection between 9 October 2023 and 9 January 2024 in 23,895 XBB.

Relative vaccine effectiveness against COVID-19 hospitalisation in persons aged ≥ 65 years: results from a VEBIS network, Europe, October 2021 to July 2023.

To monitor relative vaccine effectiveness (rVE) against COVID-19-related hospitalisation of the first, second and third COVID-19 booster (vs complete primary vaccination), we performed monthly Cox regression models using retrospective cohorts constructed from electronic health registries in eight European countries, October 2021-July 2023. Within 12 weeks of administration, each booster showed high rVE (≥ 70% for second and third boosters). However, as of July 2023, most of the relative benefit has waned, particularly in persons ≥ 80-years-old, while some protection remained in 65-79-year-olds.

Early COVID-19 vaccine effectiveness of XBB.1.5 vaccine against hospitalisation and admission to intensive care, the Netherlands, 9 October to 5 December 2023.

We present early vaccine effectiveness (VE) estimates of the 2023 seasonal COVID-19 XBB.1.5 vaccine against COVID-19 hospitalisation and admission to an intensive care unit (ICU) in previously vaccinated adults ≥ 60 years in the Netherlands.

Effects of COVID-19 vaccination and previous infection on Omicron SARS-CoV-2 infection and relation with serology.

An increasing proportion of the population has acquired immunity through COVID-19 vaccination and previous SARS-CoV-2 infection, i.e., hybrid immunity, possibly affecting the risk of new infection.

Effect of COVID-19 vaccination on mortality by COVID-19 and on mortality by other causes, the Netherlands, January 2021-January 2022.

Background: We aimed to estimate vaccine effectiveness (VE) against COVID-19 mortality, and to explore whether an increased risk of non-COVID-19 mortality exists in the weeks following a COVID-19 vaccine dose.

Methods: National registries of causes of death, COVID-19 vaccination, specialized health care and long-term care reimbursements were linked by a unique person identifier using data from 1 January 2021 to 31 January 2022. We used Cox regression with calendar time as underlying time scale to, firstly, estimate VE against COVID-19 mortality after primary and first booster vaccination, per month since vaccination and, secondly, estimate risk of non-COVID-19 mortality in the 5 or 8 weeks following a first, second or first booster dose, adjusting for birth year, sex, medical risk group and country of origin.

Novel 4 lineage associated with an upsurge in invasive group A streptococcal disease in the Netherlands, 2022.

Invasive group A streptococcal (iGAS) disease cases increased in the first half of 2022 in the Netherlands, with a remarkably high proportion of 4 isolates. Whole-genome sequence analysis of 66 4 isolates, 40 isolates from the pre-coronavirus disease 2019 (COVID-19) pandemic period 2009-2019 and 26 contemporary isolates from 2022, identified a novel lineage (M4), which accounted for 85 % of 4 iGAS cases in 2022. Surprisingly, we detected few isolates of the 4 hypervirulent clone, which has replaced nearly all other 4 in the USA and the UK.

Number of COVID-19 hospitalisations averted by vaccination: Estimates for the Netherlands, January 6, 2021 through August 30, 2022.

Background: Vaccines against COVID-19 have proven effective in preventing COVID-19 hospitalisation. In this study, we aimed to quantify part of the public health impact of COVID-19 vaccination by estimating the number of averted hospitalisations. We present results from the beginning of the vaccination campaign ('entire period', January 6, 2021) and a subperiod starting at August 2, 2021 ('subperiod') when all adults had the opportunity to complete their primary series, both until August 30, 2022.

Vaccine effectiveness of primary and booster COVID-19 vaccinations against SARS-CoV-2 infection in the Netherlands from July 12, 2021 to June 6, 2022: A prospective cohort study.

Objectives: We estimated vaccine effectiveness (VE) of primary and booster vaccinations against SARS-CoV-2 infection overall and in four risk groups defined by age and medical risk condition during the Delta and Omicron BA.1/BA.2 periods.

[Invasive group A streptococcal infections in the Netherlands].

Group A streptococcal (GAS) infections are caused by the Gram-positive bacterium Streptococcus pyogenes. Infection can occur via droplet infection from the throat and via (in)direct contact with infected people. GAS can cause a wide variety of diseases, ranging from superficial skin infections, pharyngitis and scarlet fever, to serious invasive diseases such as puerperal sepsis, pneumonia, necrotising soft tissue infections (NSTI) (also known as necrotising fasciitis/myositis), meningitis and streptococcal toxic shock syndrome (STSS).

Effectiveness of bivalent mRNA booster vaccination against SARS-CoV-2 Omicron infection, the Netherlands, September to December 2022.

We used data of 32,542 prospective cohort study participants who previously received primary and one or two monovalent booster COVID-19 vaccinations. Between 26 September and 19 December 2022, relative effectiveness of bivalent original/Omicron BA.1 vaccination against self-reported Omicron SARS-CoV-2 infection was 31% in 18-59-year-olds and 14% in 60-85-year-olds.

Higher risk of SARS-CoV-2 Omicron BA.4/5 infection than of BA.2 infection after previous BA.1 infection, the Netherlands, 2 May to 24 July 2022.

BackgroundIn summer 2022, SARS-CoV-2 Omicron BA.5 became dominant in Europe. In vitro studies have shown a large reduction of antibody neutralisation for this variant.

Increase in invasive group A streptococcal () infections (iGAS) in young children in the Netherlands, 2022.

In 2022, a sevenfold increase in the number of notifiable invasive (iGAS) infections among children aged 0-5 years was observed in the Netherlands compared with pre-COVID-19 pandemic years. Of 42 cases in this age group, seven had preceding or coinciding varicella zoster infections, nine were fatal. This increase is not attributable to a specific type.

SARS-CoV-2 TEST OUTCOMES AMONG DENTISTS AND DENTAL HYGIENISTS WITH COVID-19-LIKE COMPLAINTS - A RETROSPECTIVE ANALYSIS FROM THE NETHERLANDS.

Objective: This retrospective analysis aimed to evaluate, among individuals with COVID-19-like symptoms, the percentage of SARS-CoV-2 positive oral health care workers relative to health care workers in general and a non-close-contact occupation reference group in the Netherlands.

Materials And Methods: Data was retrospectively analyzed based on data extracted from the CoronIT database. This contained mass testing data for those experiencing symptoms compatible with COVID-19 recorded from June 2020 up to February 2021.

The dynamics of scarlet fever in The Netherlands, 1906-1920: a historical analysis.

Scarlet fever, an infectious disease caused by , largely disappeared in developed countries during the twentieth century. In recent years, scarlet fever is on the rise again, and there is a need for a better understanding of possible factors driving transmission. Using historical case notification data from the three largest cities in The Netherlands (Amsterdam, Rotterdam and The Hague) from 1906 to 1920, we inferred the transmission rate for scarlet fever using time-series susceptible-infected-recovered (TSIR) methods.

COVID-19 vaccine effectiveness against SARS-CoV-2 infection during the Delta period, a nationwide study adjusting for chance of exposure, the Netherlands, July to December 2021.

BackgroundDifferential SARS-CoV-2 exposure between vaccinated and unvaccinated individuals may confound vaccine effectiveness (VE) estimates.AimWe conducted a test-negative case-control study to determine VE against SARS-CoV-2 infection and the presence of confounding by SARS-CoV-2 exposure.MethodsWe included adults tested for SARS-CoV-2 at community facilities between 4 July and 8 December 2021 (circulation period of the Delta variant).

Protection of COVID-19 vaccination and previous infection against Omicron BA.1, BA.2 and Delta SARS-CoV-2 infections.

Given the emergence of the SARS-CoV-2 Omicron BA.1 and BA.2 variants and the roll-out of booster COVID-19 vaccination, evidence is needed on protection conferred by primary vaccination, booster vaccination and previous SARS-CoV-2 infection by variant.

Effectiveness of complete primary vaccination against COVID-19 at primary care and community level during predominant Delta circulation in Europe: multicentre analysis, I-MOVE-COVID-19 and ECDC networks, July to August 2021.

IntroductionIn July and August 2021, the SARS-CoV-2 Delta variant dominated in Europe.AimUsing a multicentre test-negative study, we measured COVID-19 vaccine effectiveness (VE) against symptomatic infection.MethodsIndividuals with COVID-19 or acute respiratory symptoms at primary care/community level in 10 European countries were tested for SARS-CoV-2.