Estimating the effect of COVID-19 vaccination and prior infection on Ct values as a proxy of SARS-CoV-2 viral load.

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.

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.

Household chaos and parenting: The effect of household chaos does not depend on sensory-processing sensitivity and self-regulation.

Previous studies have found evidence for a causal effect of household chaos on parenting and suggest that this effect may be stronger for parents with higher sensory-processing sensitivity (SPS) or lower self-regulation. This study investigates whether primary caregivers of children around age 1.5-2 years show greater improvement in parenting after a decrease in household chaos if parents have higher SPS or lower self-regulation.

Effectiveness of a COVID-19 contact tracing app in a simulation model with indirect and informal contact tracing.

During 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.

Assessment of hybrid population immunity to SARS-CoV-2 following breakthrough infections of distinct SARS-CoV-2 variants by the detection of antibodies to nucleoprotein.

Immunity 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.