Incidence, symptom clusters and determinants of post-acute COVID symptoms: a population-based surveillance in community-dwelling users of the COVID RADAR app.

Objectives: This study aims to describe the incidence, symptom clusters and determinants of post-acute COVID symptoms using data from the COVID RADAR app in the Netherlands.

Design: Prospective cohort.

Setting: General population in the Netherlands from April 2020 to February 2022.

Coagulation and inflammatory response after intramuscular or intradermal mRNA-1273 SARS-CoV-2 vaccine: secondary analysis of a randomized trial.

Background: Fractional-dosed intradermal (i.d.) vaccination produces antibody concentrations above the proposed proxy for protection against severe disease as compared with intramuscular (i.

[Indoor sporting during the COVID-19 pandemic: analysis with data from the COVID RADAR app].

Indoor sporting locations have been forced to stay closed longer than outdoor sporting locations during the lockdowns introduced during the COVID-19 pandemic. This research addresses the question whether exercising indoors does raise one's risk of infection with SARS-CoV‑2. This analysis was performed using data from the COVID RADAR app and accounted for user differences in age, vaccine status, sex, other risky behavior, SARS-CoV‑2 prevalence and quality of living environment.

COVID RADAR app: Description and validation of population surveillance of symptoms and behavior in relation to COVID-19.

Background: Monitoring of symptoms and behavior may enable prediction of emerging COVID-19 hotspots. The COVID Radar smartphone app, active in the Netherlands, allows users to self-report symptoms, social distancing behaviors, and COVID-19 status daily. The objective of this study is to describe the validation of the COVID Radar.