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Overview

People who have had severe Covid that required a stay in hospital have higher subsequent rates of mental illness, a study on health data from over 18 million people has shown. What is more, Covid’s harmful effects on mental health─ which included common illnesses such as depression as well as more serious mental illness ─ persisted for up to a year. The work has underlined the importance of Covid vaccination for everyone, because it greatly reduced the risk of hospitalisation with Covid.

The challenge

Previous studies had shown that severe Covid is linked with mental illness, but there was little evidence on what part vaccination might play in this effect. To address this, members of the carried out the largest research project ever done on Covid’s association with mental illness; big enough to look at how  the link might differ according to people’s gender, ethnicity and the severity of their Covid, as well as investigating a range of mental illnesses and the effects of vaccination.

The solution

The researchers used the secure software platform to access and analyse over 18 million people’s anonymised linked GP records, hospital records, ONS death records and Covid testing and vaccination data. They looked at associations of Covid with later depression, anxiety, eating disorders, self-harm, PTSD, addiction, psychosis and suicide.

The study analysed data on three groups of people from two different time periods during the pandemic. The first, and largest, group (18.6 million people), was from January 2020 to June 2021 and included people who had Covid before vaccines were available. The other two groups were from June 2021 onwards, when the Delta variant of Covid was dominant and vaccines were available, comprising vaccinated people (14 million) and unvaccinated people (3 million).

The study found that in each group, the incidence of mental illness was higher after Covid that was severe enough for admission to hospital, compared to the incidence before, or without Covid, and that the association persisted for up to a year. However, the rate of mental illness was not markedly higher after non-hospitalised Covid. The association of Covid with mental illness did not differ much by sex, age or ethnicity, the study found.

“Vaccination greatly reduces the risk of severe COVID, so we found associations of Covid with subsequent mental illness were limited in in the vaccinated group,” says the University of Bristol’s Dr Venexia Walker, lead author of the study. “We observed these patterns for most conditions that we looked at, from the more common conditions like depression and anxiety through to the more serious ones,” she adds.

The impact

There’s a clear message for healthcare professionals and the public from this research: the long-term mental health consequences of Covid are largely limited to more severe Covid that requires a stay in hospital.

Co-lead author Professor Jonathan Sterne says: “What surprised me is that there was essentially no relationship of Covid, or a very limited one, with subsequent mental ill health in people who were not hospitalised.”

“The public health message is that we need to avoid people being hospitalised with Covid, through vaccinating people at risk” he adds.

This work is part of a series of studies looking at Covid’s long term effects on different health conditions being conducted by the Longitudinal Health and Wellbeing National COVID-19 National Core Study, which brings together population cohorts and national anonymised electronic health records to inform policy.  As time goes on, the researchers will have the opportunity to see how long Covid’s negative effects on mental illness persist.

These studies have a wider legacy for science: because they are carried out in OpenSAFELY, all code is shared, well annotated and freely available for use by scientists worldwide for the progression of global knowledge on Covid. The team created logical units of analytic code called Reusable Actions, so the analyses for this study can easily be reproduced by others.

The next steps will be to explore other disease areas, says Professor Sterne: “We eagerly await approval for non-Covid research in OpenSAFELY and we’re raring to go as soon as those permissions are available,” he explains.