Obesity and COVID-19: are they linked?
02 June 2020
In March this year, the World Health Organisation (WHO) declared COVID-19 (the disease caused by the SARS-COV-2 virus) a pandemic.
Early research has highlighted a range of factors associated with the severity of COVID-19. These include whether an individual is older, is male, is of Asian or black ethnicity and whether they have other pre-existing conditions.
Obesity is one of these factors.
NHS Inform in Scotland1, Public Health England2, and the US Centers for Disease Control and Prevention3 (CDC) all state that those with a body mass index (BMI) of 40kg/m2 or above have a higher risk of severe illness in COVID-19. Those with a BMI in this category have been advised to follow strict physical distancing measures. Despite this and the emerging research implicating obesity as a risk factor, obesity has not been formally recognised by the WHO as an independent risk factor for COVID-19.
What do we know about COVID-19 and obesity so far?
Researchers from countries including China, US, France, Italy and UK have found links between having a higher BMI and an increased risk of hospitalisation, more serious complications and, in some studies, death in COVID-19 patients.
Early research from China found that 42.7% of all COVID-19 patients in a hospital in Shenzhen were either overweight or had obesity17. They found that BMI was also linked to an increased likelihood of developing severe pneumonia, which increased as BMI increased. This was backed up by another study in Zhejiang, which found that of COVID-19 in one hospital, those with more severe illness had significantly higher BMI than those with less severe illness18.
In the US, research from New York City found that obesity was the second most significant risk factor for hospitalisation, following age over 6519. Another report from 12 hospitals in New York City found obesity to be one of the most common pre-existing conditions in patients hospitalised with COVID-19: obesity was recorded in 41.7% of patients20.
A large study by the CDC found that obesity was the most common pre-existing health condition in younger people hospitalised with COVID-19: 59% of these patients had obesity21. This association has also been observed elsewhere in the US22, and in Italy24, where a third of patients who dead with COVID-19 in a study of 3200 people had type 2 diabetes, and just under a third had cardiovascular disease24.
In the UK, a report was published by the Intensive Care National Audit and Research Centre (ICNARC) on 15th May of 8699 patients in critical care units with confirmed COVID-19 in England, Wales and Northern Ireland25. Where BMI was recorded, 73.8% were classed as overweight and 38.6% of these patients had obesity. Patients with overweight or obesity were far more likely to require respiratory or renal support than those without.
Most recently, in the largest COVID-19 study to date, and after taking into account factors such as age, sex, ethnicity and smoking status (to make sure that these factors were not influencing the results), researchers found that increasing BMI was associated with an increased the likelihood of dying in hospital27.
Why might people with obesity be at higher risk of complications?
There are a number of reasons why people with obesity are at increased risk of severe illness from viruses or respiratory illnesses:
- Obesity causes an underlying state of inflammation in the body, which can affect its ability to fight a virus4,5,6
- Obesity is a risk factor for other conditions, like type 2 diabetes. It is common for people with obesity to have several conditions at once. Many of the underlying conditions listed by Public Health England within their social distancing guidance are associated with obesity10
- Lung function is often impaired in those with obesity11, as is lung volume and capacity12
- Standard treatment may be affected, for example, ‘proning’ (turning people on to their front) has become standard treatment in COVID-19 to improve oxygenation to particular areas of the lungs. In patients with obesity, this is much more difficult, and may not be possible in patients with severe obesity4
It is increasingly likely that obesity may be an independent risk factor in COVID-19 severity; however, there is a need for more research and a standardised approach to collecting information on BMI4. There are known links between socio-economic status (SES) and obesity and evidence is emerging for an association between obesity, SES and COVID-19, with poorer outcomes for those from more deprived areas25. By collecting better data on patients with confirmed COVID-19, risk factors can be determined and groups most at risk from the virus can be identified clearly. This information can be used to tailor prevention measures toward groups who require the most protection.
Read the full Obesity and COVID-19 briefing, here.
This blog supplements one of a series of briefings produced by Obesity Action Scotland covering a wide range of obesity-related topics. Obesity Action Scotland provides clinical leadership and independent advocacy for a multifactorial approach on preventing and reducing overweight and obesity in Scotland, recognising the multiple causes of obesity. For more information, or to read our range of briefings and blogs, visit our website at www.obesityactionscotland.org
- NHS Inform (2020) Coronavirus (COVID-19): General advice. People at higher risk of severe illness. In: Illnesses Cond. https://www.nhsinform.scot/illnesses-and-conditions/infections-and-poisoning/coronavirus-covid-19/coronavirus-covid-19-general-advice. Accessed 4 May 2020
- Public Health England (2020) Staying at home and away from others (social distancing). https://www.gov.uk/government/publications/full-guidance-on-staying-at-home-and-away-from-others/full-guidance-on-staying-at-home-and-away-from-others. Accessed 1 May 2020
- Centers for Disease Control and Prevention (2020) Groups at Higher Risk for Severe Illness. https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/groups-at-higher-risk.html. Accessed 14 Apr 2020
- World Obesity Federation, The Obesity Society, European Association for the Study of Obesity (2020) The Collision of Two Pandemics : COVID-19 and Obesity Housekeeping Rules
- Richard C, Wadowski M, Goruk S, et al (2017) Individuals with obesity and type 2 diabetes have additional immune dysfunction compared with obese individuals who are metabolically healthy. BMJ Open Diabetes Res Care 5:e000379
- Ahn S, Sohn S, Lee S, et al (2015) The effect of lipopolysaccharide-induced obesity and its chronic infammation on infuenza virus-related pathology. Env Toxicol Pharmacol 40:924–930
- Honce R, Schultz-Cherry S (2019) Impact of obesity on influenza A virus pathogenesis, immune response, and evolution. Front Immunol 10:1–15. https://doi.org/10.3389/fimmu.2019.01071
- Park S, Jeon J-H, Min B-K, et al (2018) Role of the pyruvate dehydrogenase complex in metabolic remodeling: diferential pyruvate dehydrogenase complex functions in metabolism. Diabetes Metab J 42:270–281
- Noah TL, Chakladar S, Hudgens MG, Weir SS (2017) Increased risk of influenza among vaccinated adults who are obese. 41:1324–1330. https://doi.org/10.1038/ijo.2017.131.Increased
- Public Health England (2020) Guidance on social distancing for everyone in the UK. In: Guidance. https://www.gov.uk/government/publications/covid-19-guidance-on-social-distancing-and-for-vulnerable-people/guidance-on-social-distancing-for-everyone-in-the-uk-and-protecting-older-people-and-vulnerable-adults. Accessed 14 Apr 2020
- Gong MN, Bajwa EK, Thompson BT, Christiani DC (2010) Body mass index is associated with the development of acute respiratory distress syndrome. Thorax 65:44–50. https://doi.org/10.1136/thx.2009.117572
- Melo LC ost., Silva MA layd. M da, Calles AC arolin. do N (2014) Obesity and lung function: a systematic review. Einstein (Sao Paulo) 12:120–125. https://doi.org/10.1590/S1679-45082014RW2691
- Zheng Q, Cui G, Chen J, et al (2015) Regular exercise enhances the immune response against microbial antigens through upregulation of toll-like receptor signaling pathways. Cell Physiol Biochem 37:735–746
- Reidy P, Yonemura N, Madsen J, et al (2019) An accumulation of muscle macrophages is accompanied by altered insulin sensitivity after reduced activity and recovery. Acta Physiol 226:1–16
- Luzi L, Radaelli MG (2020) Influenza and obesity: its odd relationship and the lessons for COVID-19 pandemic. Acta Diabetol. https://doi.org/10.1007/s00592-020-01522-8
- Maier HE, Lopez R, Sanchez N, et al (2018) Obesity increases the duration of influenza a virus shedding in adults. J Infect Dis 218:1378–1382. https://doi.org/10.1093/infdis/jiy370
- Qingxian C, Fengjuan C, Fang L, et al (2020) Obesity and COVID-19 Severity in a Designated Hospital in Shenzhen, China. Lancet
- Chen Q, Zheng Z, Zhang C, et al (2020) Clinical characteristics of 145 patients with corona virus disease 2019 ( COVID ‑ 19 ) in Taizhou , Zhejiang , China. Infection. https://doi.org/10.1007/s15010-020-01432-5
- Jones SA, Cerfolio RJ (2020) Factors associated with hospitalization and critical illness among 4,103 patients with Covid-19 disease in New York City
- Richardson S, Hirsch J, Narasimhan N, Crawford J (2020) Presenting Characteristics, Comorbidities, and Outcomes Among 5700 Patients Hospitalized With COVID-19 in the New York City Area. JAMA - J Am Med Assoc
- Garg S, Kim L, Whitaker M, O’Halloran A (2020) Hospitalization Rates and Characteristics of Patients Hospitalized with Laboratory-Confirmed Coronavirus Disease 2019 — COVID-NET, 14 States, March 1–30, 2020
- Lighter J, Phillips M, Hochman S, Sterling S (2020) Obesity in patients younger than 60 years is a risk factor for Covid-19 hospital admission. Infect Dis Soc Am. https://doi.org/10.1093/ntr/nty008/4823697
- Simonnet A, Chetboun M, Poissy J, et al (2020) High prevalence of obesity in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) requiring invasive mechanical ventilation. Obesity 0–1. https://doi.org/10.1002/oby.22831
- Palmieri P, Andrianou X, Bella A, Bellino S (2020) Characteristics of COVID-19 patients dying in Italy Report based on available data on March 20th , 2020. Italy
- ICNARC (2020) Report on COVID-19 in critical care. 15th May 2020. Intensive Care Natl Audit Res Cent 1–24
- Docherty AB, Harrison EM, Green CA, et al (2020) Features of 16,749 hospitalised UK patients with COVID-19 using the ISARIC WHO Clinical Characterisation Protocol
- Williamson E, Walker A, Bhaskaran K, Bacon S (2020) OpenSAFELY: factors associated with COVID-19-related hospital death in the linked electronic health records of 17 million adult NHS patients. MedRxiv preprint: https://doi.org/10.1017/CBO9781107415324.004
- World Obesity Federation (2020) World Obesity Live - People at the Centre: Obesity, COVID-19 and the Patient Perspective. https://www.worldobesity.org/training-and-events/events/world-obesity-live-people-at-the-centre-obesity-covid-19-and-the-patient-perspective. Accessed 20 Apr 2020
- Shetty S, Parthasarathy S (2015) Obesity hypoventilation syndrome. Curr Pulmonol Rep 4:42–55. https://doi.org/10.5222/otd.supp1.2014.015
- Huang J, Wang X, Zheng K, et al (2020) Obesity Hypoventilation Syndrome and Severe COVID-19. Metab Clin Exp 108:. https://doi.org/10.1016/0002-8223(94)92576-3
- Zhou P, Yang X Lou, Wang XG, et al (2020) A pneumonia outbreak associated with a new coronavirus of probable bat origin. Nature 579:270–273. https://doi.org/10.1038/s41586-020-2012-7
- Jia X, Yin C, Lu S, et al (2020) Two Things About COVID-19 Might Need Attention. Preprints 1:. https://doi.org/10.20944/preprints202002.0315.v1