The REACT Long COVID (REACT-LC) study seeks to understand how biological, environmental and social factors determine why some people who are infected with COVID-19 continue to have symptoms for several weeks or months –  a condition called Long Covid - while others don’t. The study draws on the 2.4 million REACT participants.

The strand of the study focused on investigating biological factors, carried out in collaboration with Genomics England, invited participants to attend an assessment clinic where clinical measurements and biological samples were collected. A total of 10,600 participants attended the clinics and over 2,000 attended a second visit for repeated clinical data collection. So far, Whole Genome Analysis has been carried out on over 10,000 of these participants' samples as well as 4,500 RNA sequences and 2,500 inflammatory marker analyses. Further omic analyses are currently underway.

For the strand of the study exploring the social and environmental factors, 800,000 of the 2.4 million REACT participants who gave consent for re-contact were invited to take part in an online survey of health and wellbeing  and a cognitive test. Over 250,000 responded to the questionnaire, over half of whom also did an online cognitive test. Findings from these questionnaires showed that female sex, having more than one comorbidity and being infected when wild-type variant was dominant, were associated with higher probability of symptoms lasting more than 2 weeks and longer recovery time in those with persistent symptoms.

 The remaining 1.6 million REACT participants who consented to follow up/data linkage are now being invited to complete the survey alongside re-contacting those who already took part, to assess the longer-term effects of COVID-19 through a further follow up questionnaire.

In order to gain insights into the lived experience of Long Covid, 13 participants took part in a pilot interview study in 2021 and a further 60 have taken part in the main interview study to document and analyse their experiences of persistent symptoms of COVID-19 in depth. 

The study is being carried out in partnership with Queen Mary University of London, the Francis Crick Institute, Leiden University, Birmingham University and Newcastle University.