Objectives: SARS-CoV-2 viral load could be an important parameter for transmission potential. Here, we use RT-qPCR cycle threshold (Ct) values as a proxy for viral load. We assess the effect of COVID-19 vaccination and prior infection status on Ct value, while accounting for the virus variant.
View Article and Find Full Text PDFDuring the COVID-19 pandemic, contact tracing was used to identify individuals who had been in contact with a confirmed case so that these contacted individuals could be tested and quarantined to prevent further spread of the SARS-CoV-2 virus. Many countries developed mobile apps to find these contacted individuals faster. We evaluate the epidemiological effectiveness of the Dutch app CoronaMelder, where we measure effectiveness as the reduction of the reproduction number R.
View Article and Find Full Text PDFImmunity induced by vaccination and infection, referred to as hybrid immunity, provides better protection against SARS-CoV-2 infections compared to immunity induced by vaccinations alone. To assess the development of hybrid immunity we investigated the induction of Nucleoprotein-specific antibodies in PCR-confirmed infections by Delta or Omicron in vaccinated individuals (n = 520). Eighty-two percent of the participants with a breakthrough infection reached N-seropositivity.
View Article and Find Full Text PDFBackground: Children play a key role in the transmission of many infectious diseases. They have many of their close social encounters at home or at school. We hypothesized that most of the transmission of respiratory infections among children occur in these two settings and that transmission patterns can be predicted by a bipartite network of schools and households.
View Article and Find Full Text PDFBackgroundIn 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.
View Article and Find Full Text PDFGiven 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.
View Article and Find Full Text PDFThe extent to which severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) break through infection- or vaccine-induced immunity is not well understood. We analyzed 28,578 sequenced SARS-CoV-2 samples from individuals with known immune status obtained through national community testing in the Netherlands from March to August 2021. We found evidence of an increased risk of infection by the Beta (B.
View Article and Find Full Text PDFThe SARS-CoV-2 Omicron variant has a growth advantage over the Delta variant because of higher transmissibility, immune evasion or shorter serial interval. Using S gene target failure (SGTF) as indication for Omicron BA.1, we identified 908 SGTF and 1,621 non-SGTF serial intervals in the same period.
View Article and Find Full Text PDFInfections with the Omicron SARS-CoV-2 variant are rapidly increasing worldwide. Among 174,349 SARS-CoV-2-infected individuals (≥ 12 years), we observed an increased risk of S gene target failure, predictive of the Omicron variant, in vaccinated (odds ratio (OR): 3.6; 95% confidence interval (CI): 3.
View Article and Find Full Text PDFThe composition of the gut microbiota is affected by a number of factors, including the innate and adaptive immune system. The major histocompatibility complex (MHC), or the human leukocyte antigen (HLA) in humans, performs an essential role in vertebrate immunity and is very polymorphic in different populations. HLA determines the specificity of T lymphocyte and natural killer (NK) cell responses, including those against the commensal bacteria present in the human gut.
View Article and Find Full Text PDFRespiratory syncytial virus (RSV) infection is a leading cause of hospitalization in infants. Underlying risk factors for RSV infection in the general population are not well understood, as previous work has focused on severe outcomes of infection in a clinical setting. Here we use RSV-specific IgG and IgA antibody measurements from two population-based cross-sectional serosurveys carried out in the Netherlands (n = 682) to classify children up to 5 years as seronegative or seropositive.
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