It’s not just old people: obese young adults are ending up critically ill in hospital with Coronavirus

John Dyett
Med J Aust
Published online: 26 August 2020

This is a preprint only. The final version of this article is available at:

While healthcare systems around the world respond to the unprecedented challenge presented by COVID-19, frontline clinician-researchers are doing their best to understand this new and poorly-understood disease. Australia has largely been spared as a result of community engagement with public health interventions. Due to this success local experience with the disease has been relatively limited. Evidence from overseas experiences are beginning to paint a clear picture of who is at risk of critical illness due to COVID-19.

Early evidence from China[1] suggested critical illness due to COVID-19 was more likely in the presence of common health conditions including hypertension, diabetes and cardiovascular disease. New evidence from the UK[2], China[3], France[4] and USA[5] suggest a possible link between obesity and more severe coronavirus disease. Weight appears to be an important risk factor for severe coronavirus disease, especially for young adults.

In the first study to link obesity to severe COVID-19 disease in 383 patients in China[3], the odds ratio (95% confidence intervals) for severe pneumonia in obesity was 5.70 (1.83 – 17.76) in men. In this retrospective cohort study from France describing 124 patients admitted to Intensive Care, the odds ratio for invasive mechanical ventilation (IMV) with body mass index (BMI) > 35 versus patients with BMI < 25 was 7.36 (1.63 – 33.14; p=0.02). In the first 383 patients admitted with COVID-19 to two New York hospitals, patients receiving IMV were more likely to be obese[5], consistent with other studies.

The data, while preliminary, indicate obesity may even be the second largest risk factor for severe COVID-19 disease, after older age. This may surprise young adults, as health messaging so far has importantly stressed older people and those with chronic disease as being more at risk from COVID-19.

This recent UK study[2] looked at more than 8,250 hospitalised critically ill COVID-19 patients across 252 hospitals. It showed more than 38% of adults presenting to hospital critically ill due to COVID-19 were obese. However only about 29% of UK adults are obese, so it appears that obese patients are over-represented amongst those critically ill due to COVID-19. This suggests an association between higher weight and more severe COVID-19 illness.

While some of the risk factors for COVID-19 infection and severe disease are not easily modifiable, such as male sex[6] or being a healthcare worker[7], some are. The COVID-19 pandemic has highlighted to all the need for governments around the world to address the “silent” pandemic[8] of non-communicable diseases such as overweight and obesity.

We must take action now to protect our communities and generate resilience against threats such as COVID-19 in the future. We can do this today by addressing the silent pandemic and ensuring that everyone enjoys better health.


  1. Guan WJ, Ni ZY, Hu Y, Liang WH, Ou CQ, He JX, et al. Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med. 2020.
  2. Intensive Care National Audit and Research Centre (ICNARC) Case Mix Programme Database. ICNARC Report on COVID-19 in critical care, 8 May 2020. London, UK. (accessed May 2020)
  3. Qingxian C, Fengjuan C, Fang L, Xiaohui L et al. Obesity and COVID-19 Severity in a Designated Hospital in Shenzhen, China. Preprints with The Lancet. (accessed Apr 2020)
  4. Simonnet A, Chetboun M, Poissy J, Raverdy V et al. High prevalence of obesity in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) requiring invasive mechanical ventilation. (accessed Apr 2020)
  5. Goyal P, Choi JJ, Pinheiro LC, Schenck EJ et al. Clinical Characteristics of Covid-19 in New York City. N Engl J Med. 2020.
  6. Peckham H, de Gruijter N, Raine C, Radziszewska A et al. Sex-bias in COVID-19: a meta-analysis and review of sex differences in disease and immunity. Preprint. (accessed Apr 2020)
  7. Marsh S. At least 100 UK health workers have died from coronavirus, figures show. (accessed Apr 2020)
  8. Roth J, Qiang X, Marban S, Redelt H et al. The Obesity Pandemic: where have we been and where are we going? Obesity Research, 12: 88S-101S. doi:10.1038/oby.2004.27
  • John Dyett1,2

  • 1 Monash University
  • 2 Box Hill Hospital


Competing interests:

Competing interests: No relevant disclosures


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