Complications associated with COVID-19

Published: 22 July 2021

A new study co-authored by the Institute's Dr Antonia Ho and published in The Lancet, is the first to systematically assess a range of in-hospital complications, and their associations with age, sex and ethnicity, and their outcomes for the patients.

Figure 2a: Outcomes and mortality after complications (A) Differences in complication rates, age, sex, and comorbidity.

A new study co-authored by the Institute's Dr Antonia Ho is the first to systematically assess a range of in-hospital complications, and their associations with age, sex and ethnicity, and their outcomes for the patients. 

Published in The Lancet, this observational study of more than 70,000 people in 302 UK hospitals has found that one in two people hospitalised with COVID-19 developed at least one complication.

The authors say these complications are likely to have important short- and long-term impacts for patients, healthcare utilisation, healthcare system preparedness, and society amidst the ongoing COVID-19 pandemic.

They also note that these complications are different to long COVID symptoms in patients with COVID-19 who were not hospitalised.

Complications in patients admitted to hospital with COVID-19 were found to be high, even in young, previously healthy individuals – with 27 per cent of 19-29 year olds and 37 per cent of 30-39 year-olds experiencing a complication.

Furthermore, acute complications are associated with reduced ability to self-care at discharge – with 13 per cent of 19-29 year olds and 17 per cent of 30-39 year olds unable to look after themselves once discharged from hospital.

The study looked at cases between 17 January and 4 August 2020 before vaccines were widely available, and new variants of the virus had not arisen.

However, the findings remain relevant in dispelling suggestions that COVID-19 presents no risk to younger healthy adults, many of whom remain unvaccinated.

The authors warn that policymakers must consider the risk of complications for those who survive COVID-19, not just mortality, when making decisions around easing restrictions.

They predict that COVID-19 complications are likely to cause significant challenges for individuals and for the health and social care system in the coming years, and that policy makers and health-care planners should anticipate that large amounts of health and social care resources will be required to support those who survive COVID-19.

Chief Investigator and joint senior author of the study, Professor Calum Semple, University of Liverpool, UK, says: “This work contradicts current narratives that COVID-19 is only dangerous in people with existing comorbidities and the elderly. Dispelling and contributing to the scientific debate around such narratives has become increasingly important.

"Disease severity at admission is a predictor of complications even in younger adults, so prevention of complications requires a primary prevention strategy, meaning vaccination.”

Dr Ho, Consultant in Infectious Diseases at our Centre for Virus Research, said: “This study highlights that in-hospital complications in hospitalised COVID-19 patients are extremely common.

"This is the case even among young people with no underlying health conditions, with one or more complications occurring in approximately one in four 20-29-year-olds and more than one in four 30-39 year-olds.

"It is important for young adults to understand that severe disease do occur in their age group, and most effective prevention is vaccination.

"We are still trying to understand how long the observed complications can persist for. However, given the high number of patients hospitalised with COVID-19 over the last 18 months, these findings may have significant impact on health and social care system.”


Characterisation of in-hospital complications associated with COVID-19 using the ISARIC WHO Clinical Characterisation Protocol UK: a prospective, multi-centre cohort study

  • Thomas M Drake, Aya M Riad, Cameron J Fairfield, Conor Egan, Stephen R Knight, Riinu Pius, Hayley E Hardwick, Lisa Norman, Catherine A Shaw, Kenneth A McLean, A A Roger Thompson, Antonia Ho, Olivia V Swann, Michael Sullivan, Felipe Soares, Karl A Holden, Laura Merson, Daniel Plotkin, Louise Sigfrid, Thushan I de Silva, Michelle Girvan, Clare Jackson, Clark D Russell, Jake Dunning, Tom Solomon, Gail Carson, Piero Olliaro, Jonathan S Nguyen-Van-Tam, Lance Turtle, Annemarie B Docherty, Peter JM Openshaw, J Kenneth Baillie, Ewen M Harrison, Malcolm G Semple, on behalf of the ISARIC4C investigators
  • Published: 17 July, 2021. DOI: https://doi.org/10.1016/S0140-6736(21)00799-6

Image legend: Figure 2a - Outcomes and mortality after complications (A) Differences in complication rates, age, sex, and comorbidity.

First published: 22 July 2021