- The COVID-19 pandemic disproportionately impacts the people from vulnerable populations, including those with medical conditions such as obesity and diabetes mellitus (DM). Given the high prevalence of obesity and DM, it is necessary and important that we protect individuals with these conditions from the COVID-19 pandemic.
- Evidence from relevant studies investigating the effects of obesity or DM on COVID-19 outcomes was consistent. Obesity and DM were associated with poor prognosis of COVID-19 such as greater disease severity and increased mortality.
- There is a paucity of empirical evidence regarding the impacts of obesity or DM on the protective effects of the current available COVID-19 vaccines. Current available results were mixed. More research is needed to ascertain the association between vaccine effectiveness and obesity or DM. Post-marketing surveillance of the safety of current available COVID-19 vaccines in patients with obesity or DM is also warranted.
- In the absence of robust evidence, any speculation on the vaccine effectiveness in vulnerable populations is discouraged in order to maintain the public trust and acceptance over the COVID-19 vaccination campaign.
“... We are stronger together, today, tomorrow, and always.”
Justin Trudeau, Prime Minister of Canada (CTV News)
Over a year since the World Health Organization (WHO) declared the COVID-19 a pandemic, this global public health crisis has presented an unprecedented stressor to patients and health care systems all over the world. To date, there have been more than 123 million global cases and over 2.7 million deaths due to COVID-19 (Johns Hopkins Coronavirus Resource Center).
Like other crises, the COVID-19 pandemic disproportionately impacts the people from vulnerable populations, including but not limited to racial/ethnic minorities, the elderly, immigrants/refugees, socioeconomically disadvantaged, disabled, and underinsured individuals, as well as people with medical conditions such as obesity and diabetes mellitus (DM) (Clark et al., 2020; Dietz et al., 2020; Kavanagh et al., 2020; Khatana, et al., 2020; Kuy et al., 2020; Liu et al., 2020; Lone et al., 2020; Muniyappa et al., 2020).
Effective vaccines against COVID-19 are our hope to end the pandemic. However, challenges often exist in vaccine development and deployment for the vulnerable populations. For example, evidence suggested that obesity might increase the likelihood of a poor vaccine-induced immune response (Painter et al., 2015). Additionally, previous research also showed that people with DM might have an impaired immune response induced by the hepatitis B vaccine (Li Volti et al., 1998).
Despite the challenges and difficulties, we must focus on the vulnerable populations during the COVID-19 pandemic because, As Kuy et al. (2020) pointed out, “It is both morally right to advance health equity among vulnerable populations and essential to protect the health of the public.”
Obesity and DM are prevalent conditions among the vulnerable populations. The WHO estimated that 650 million adults were obese globally in 2016 (WHO, 2020). In addition, according to the Centers for Disease Control and Prevention (CDC), in the United States of America (USA) alone, over 34 million people (10.5% of the total population) had DM in 2018 (CDC, 2020). Obesity and diabetes, especially type 2 DM, are closely related: the epidemic of obesity has resulted in the rising incidence of type 2 DM among both children and adults (Al-Goblan et al., 2014).
Given the large number of vulnerable individuals with obesity or DM, it is imperative that we protect them from the COVID-19 pandemic. In this OE Original, we examine current evidence with regard to the impacts of obesity or DM on patients with COVID-19. We also discuss the development and deployment of COVID-19 vaccine in these vulnerable populations.
1.1 Impact of obesity on COVID-19 patients
Obesity is diagnosed when the body mass index (BMI) is equal to or greater than 30 kg/m2 (Overweight if BMI is equal to or greater than 25 kg/m2) (CDC, 2021).
Several empirical studies have revealed the association between obesity and poor COVID-19 outcomes. First, obesity was associated with greater COVID-19 severity. Petrilli et al. (2020) found that the risk for hospital admission due to COVID-19 was significantly associated with obesity [BMI > 40 kg/m2, odds ratio (OR): 1.5, 95% confidence interval (CI): 1.0 to 2.2]. Gao et al. (2020) identified a significant association between obesity and greater COVID-19 severity after adjusting for age, sex, smoking status, hypertension, diabetes, and dyslipidemia [adjusted OR (aOR): 3.00; 95% CI: 1.22 to 7.38]. Similarly, results from Cai et al. (2020) indicated that obese people had an increased odds (aOR: 3.40; 95% CI: 1.40 to 2.86) of developing severe COVID-19 after adjusting for factors such as age, sex, epidemiological characteristics, presence of hypertension, and DM, etc.
Second, obesity was associated with higher risk of intensive care unit (ICU) admission and use of invasive mechanical ventilation (IMV). Findings from Simonnet et al. (2020) showed that a high proportion of COVID-19 patients admitted to ICU was obese (47.5%) and there was a siginicant association between obese and the use of IMV (aOR: 7.36; 95% CI: 1.63 to 33.14). Another study found that the prevalence of obesity was 1.35 times (95% CI 1.08 to 1.66) and 1.89 times (95% CI: 1.33 to 2.53) higher in patients with severe COVID-19 and in patients admitted to ICU than those in the general French population, respectively (Caussy et al., 2020). Kalligeros et al. (2020) found that severe obesity (BMI?=?35 kg/m2) was associated with admission to ICU (aOR: 5.39; 95% CI: 1.13 to 25.64), and history of obesity (BMI?=?30 kg/m2) were independently associated with the use of IMV (aOR: 6.85, 95% CI: 1.05 to 44.82). Data from Lighter et al. (2020) showed that obese patients were 2.2 times (95% CI: 1.7 to 2.9) more likely to be admitted to acute and critical care, compared with people who had no obesity.
Third, obesity was associated with the increased mortality due to COVID-19. A retrospective study showed that patients with severe obesity (BMI = 35 kg/m2) were 3.78 times more likely to die during hospitalization, compared to patients with a BMI between 25 and 34 kg/m2 (Palaiodimos et al., 2020). Another retrospective study done by Rottoli et al. (2020) found that patients with a BMI between 30 and 35 kg/m2 were more likely to be admitted to the ICU (OR: 4.96; 95% CI: 2.53 to 9.74) and those with severe obesity (BMI?=?35 kg/m2) were 12.1 times (95% CI: 3.25 to 45.1) more likely to die in hospital. A prospective cohort study following 20,133 hospitalized patients due to COVID-19 identified obesity as a significant increased risk for in-hospital mortality [hazard ratio (HR): 1.33; 95% CI: 1.19 to 1.49] (Docherty et al., 2020). Zhang et al. (2020) investigated whether obesity was a risk factor for young patients with COVID-19. The study showed that obesity was significantly associated with higher mortality (OR: 1.354; 95% CI: 1.075 to 1.704) among young patients (19 to 45 years of age) with COVID-19 (Zhang et al., 2020).
A systematic review first published in August 2020 also supported the association between obesity and poor COVID-19 outcomes (Popkin et al., 2020). The systematic review pooled then available data and showed that individuals with obesity were more likely to be hospitalized (OR: 2.13; 95% CI: 1.74 to 2.60), to be admitted to ICU (OR: 1.74; 95% CI: 1.46 to 2.08), to use IMV (OR: 1.66; 95% CI: 1.38 to 1.99), and to die due to CIVID-19 (OR: 1.48; 95% CI: 1.22 to 1.80), compared to those who were not obese (Popkin et al., 2020). A more recent systematic review corroborated previous findings (Yang et al., 2021). The study showed that patients with severe COVID-19 patients had a higher BMI [weighted mean difference (WMD): 2.67; 95% CI, 1.52 to3.82] and were more likely to have a poor prognosis of COVID-19 (OR:?2.31; 95% CI, 1.3 to 4.12), compared with non-severe COVID-19 patients (WMD?=?2.67; 95% CI, 1.52-3.82) (Yang et al., 2021).
1.2 Potential impacts of obesity on COVID-19 vaccination
Some current available COVID-19 vaccines provided data regarding the vaccine efficacy in people with obesity. In the trial for Pfizer/BioNTech mRNA vaccine (BNT162b2), obesity seemed not to affect the vaccine efficacy against COVID-19 (Polack et al., 2020). About 35.1% (13,218/37,706) of the trial participants were obese (BMI = 30 kg/m2). Subgroup analysis showed that the vaccine efficacy at seven days after the second dose in participants with obesity was 95.4% (95% CI: 86.0% to 99.1%), whereas the vaccine efficacy in participants without obesity was 94.8% (95% CI: 87.3% to 98.3%) (Food and Drug Administration, 2020a; Polack et al., 2020).
Similar results were seen in the Moderna mRNA vaccine (mRNA-1273) trial. About 6.7% (2,046/30,351) of the trial participants were severely obese (Baden et al., 2020). Subgroup analysis showed that the vaccine efficacy at 14 days after the second dose was 91.2% (95% CI: 32% to 98.9%) in patients with severe obesity (BMI = 40 kg/m2), while the vaccine efficacy among participants with no high-risk comorbidity was 94.0% (95% CI: 83.5% to 97.8%) (Food and Drug Administration, 2020b). The post-hoc analysis of the Moderna vaccine trial found that the vaccine efficacy in patients with obesity (BMI = 30 kg/m2) was 95.8% (95% CI: 82.6% to 99.0%) (Food and Drug Administration, 2020b).
In March 2021, the USA and Canada approved another COVID-19 vaccine developed by Janssen Biotech Inc., a Janssen Pharmaceutical Company of Johnson & Johnson. The Janssen vaccine (Ad26.COV2.S) is an adenovirus vector vaccine. The vaccine efficacy against moderate to severe/critical COVID19 in the research participants was 66.9% (95% CI: 59.0% to 73.4%) at least 14 days after the single-dose vaccination and 66.1% (95% CI: 55.0% to 74.8%) at least 28 days after vaccination (Food and Drug Administration, 2020c). Obesity was the most common comorbidity among the participants (28.5%, 12,492/43783). The vaccine efficacy in people with obesity was 66.8% (95% CI: 54.1% to 76.3%) at least 14 days post vaccination and 65.9% (95% CI: 47.8% to 78.3%) at least 28 days post vaccination, similar to the vaccine efficacy in the total research population (Food and Drug Administration, 2020c).
Findings from above large phase III trials inspire optimism. However, challenges remain because obesity might impact patients’ response to COVID-19 vaccination. Data on whether obesity would negatively impact COVID-19 vaccination is scarce. A recent preprint published in MedRxiv revealed that the serum level of IgG antibodies against the SARS-CoV-2 Spike protein was negatively associated with BMI in COVID-19 patients (Frasca et al., 2020). More importantly, another preprint analyzed the antibody titer seven days after the second dose of the Pfizer/BioNTech vaccine in 248 healthcare workers. It found that people with pre-obesity obesity (titer: 222.40; 95% CI: 168.9 to 292.9) or obesity (titer: 167.05; 95% CI: 90.2 to 309.3) had a significantly lower antibody titer seven days after the second dose than people who were under-weight (titer: 455.41; 95% CI: 311.5 to 665.7) or normal weight (titer: 325.84; 95% CI: 277.9 to 382.0) (P < 0.0001) (Pellini et al., 2021).
2. Diabetes mellitus (DM)
2.1 Impact of DM on COVID-19 patients
Several systematic reviews have demonstrated the association between DM and COVID-19 outcomes. A systematic review first published in April 2020 found that DM was associated with composite poor COVID-19 outcomes [relative risk (RR): 2.38; 95% CI: 1.88 to 3.03], severe COVID-19 (RR: 2.45; 95% CI: 1.79 to 3.35), and increased mortality due to COVID-19 (RR: 2.12; 95% CI: 1.44 to 3.11) (Huang et al., 2020). Other systematic reviews with narrative evidence summary also echoed the findings from Huang et al. (2020) (Abdi et al., 2020; Zaki et al., 2020).
More studies have been published since the above systematic reviews. Moreover, some of the studies further specified the respective impacts of type 1 and type 2 DM on patients with COVID-19 and indicated that both type 1 and type 2 DM would lead to poor COVID-19 outcomes.
For example, Barron et al. (2020) conducted a whole-population study to determine the associations of type 1 and type 2 DM with mortality due to COVID-19 in England. The results showed that COVID-19 patients with either type 1 DM (aOR: 2.86; 95% CI: 2.58 to 3.18) or type 2 DM (aOR: 1.80; 95% CI: 1.75 to 1.86) were more likely to die during hospitalization, compared to those without DM (Barron et al., 2020).
A prospective cohort study conducted by Gregory et al. (2021) found that DM, either type 1 and type 2, resulted in a poor prognosis of COVID-19. Specifically, compared to patients without DM, COVID-19 patients with type 1 DM were 3.9 (95% CI: 1.75 to 8.69) and 3.35 (95% CI: 1.53 to 7.33) times more likely to be hospitalized and have severe COVID-19, respectively (Gregory et al., 2021). COVID-19 patients with type 2 DM had similar odds, compared to patients without DM (for hospitalization: aOR: 3.36, 95% CI: 2.49 to 4.55; for severe illness: aOR: 3.42, 95% CI: 2.55 to 4.58) (Gregory et al., 2021).
Findings from another cohort study done by McGurnaghan et al. (2021) showed that the overall odds of developing fatal or critical care unit-treated COVID-19 among patients with DM, including type 1 and type 2, was 1.395 (95% CI: 1.304 to 1.494). The odds were 2.396 (95% CI: 1.815 to 3.163) and 1.369 (95% CI: 1.276 to 1.468) in type 1 DM and in type 2 DM, respectively (McGurnaghan et al., 2021).
2.2 Potential impacts of DM on COVID-19 vaccination
Looking at current available vaccines against COVID-19, we found that in the Pfizer/BioNTech mRNA vaccine trial, 8.4% (3,150/37,706) of the trial participants had DM, following obesity (35.1%) as one of the most frequent underlying medical conditions (Food and Drug Administration, 2020a). Subgroup analysis showed that the vaccine efficacy at seven days after the second dose of the Pfizer/BioNTech mRNA vaccine in participants with DM was 94.7% (95% CI: 66.8% to 99.9%) (Food and Drug Administration, 2020a).
In the Moderna mRNA vaccine trial, 2,858 participants had DM, accounting for about 9.4% of the research population. The vaccine efficacy at 14 days after the second dose of the Moderna vaccine was 100% (Food and Drug Administration, 2020b). Although a 66-year-old female with diabetes developed dyspnea with exertion and peripheral edema after vaccination, the serious adverse event was not considered to be related to the Moderna vaccine (Food and Drug Administration, 2020b).
In the Janssen vaccine trial, 0.4% (195/43,783) and 7.3% (3,194/43783) of the trial participants had type 1 DM and type 2 DM, respectively (Food and Drug Administration, 2020c). The subgroup analysis was done in patients with type 2 DM. The results showed that the vaccine efficacy against moderate to severe/critical COVID19 in the research participants with type 2 DM was 52.9% (95% CI: 10.5% to 76.3%) at least 14 days after the single-dose vaccination (Food and Drug Administration, 2020c). It concerns us that the vaccine efficacy at least 28 days after the single-dose vaccination in the research participants with type 2 DM was much lower, only about 23% (95% CI: -90.1% to 69.8%) (Food and Drug Administration, 2020c).
Above trial data suggested that there might be little impact of DM on the vaccine efficacy against COVID-19. Recently, a peer-reviewed study done by Dispinseri et al. (2021) supported the conclusion and found that DM had no significant effects on the kinetics and durability of the neutralizing antibody response to SARS-CoV-2, providing empirical evidence for the inclusion of individuals with DM in the early stage of the COVID-19 vaccine rollout.
However, a non-peer-reviewed Israeli study, signifying a negative association between type 2 diabetes and the Pfizer/BioNTech vaccine protection, was just posted in MedRxiv on March 17 (Yelin et al., 2021). The preprint found that the vaccine effectiveness of the Pfizer/BioNTech vaccine at 29-50 days post vaccination reduced and were less likely to protect patients with type 2 DM (OR: 0.72, 95% CI: 0.60 to 0.86), compared to the vaccine effectiveness at 1-11 days post vaccination (Yelin et al., 2021).
In this OE Original, we examined current available evidence on the effects of obesity or diabetes mellitus (DM) on COVID-19 outcomes. Results from relevant studies were consistent. There was a clear association between poor prognosis of COVID-19 with obesity or DM. COVID-19 patients who were obese or had DM (either type 1 or type 2) were more likely to have severe COVID-19, to be admitted to intensive care unit (ICU), to use of invasive mechanical ventilation (IMV), and to die during hospitalization. Extra attention needs to be paid to these vulnerable populations when diagnosing and treating COVID-19.
We further looked into the empirical evidence with regard to the impacts of obesity or DM on the effectiveness of COVID-19 vaccines. Currently, no definitive conclusion could be drawn due to lack of evidence. Most of the trial data on the Pfizer/BioNTech mRNA vaccine, the Moderna mRNA vaccine, and the recently FDA-approved Janssen adenovirus-vectored vaccine were in favor that obesity and DM had little impact on vaccine efficacy. However, results from other studies indicated the opposite and suggested that obesity or DM might lead to a reduced vaccine effectiveness. More research is urgently needed to determine the association between vaccine effectiveness and obesity or DM. In addition, robust post-marketing surveillance of the safety of current available COVID-19 vaccines in patients with obesity or DM is also warranted.
Finally, the absence of robust data should not give rise to doubts over the key role of vaccination in battling the COVID-19 pandemic. Pending clear evidence, irresponsible speculation about reduced COVID-19 vaccines effectiveness in vulnerable populations may result in increased vaccine hesitancy and decreased vaccine acceptance, which, in addition to vaccine effectiveness, are extremely important to the success of COVID-19 vaccination campaigns. Public trust in current COVID-19 vaccination efforts must be carefully maintained.
Abdi, A., et al. (2020). Diabetes and COVID-19: A systematic review on the current evidences. Diabetes Research and Clinical Practice, 166, 108347. doi:https://doi.org/10.1016/j.diabres.2020.108347
Al-Goblan, A. S., et al. (2014). Mechanism linking diabetes mellitus and obesity. Diabetes, metabolic syndrome and obesity : targets and therapy, 7, 587-591. doi:10.2147/DMSO.S67400
Baden, L. R., et al. (2020). Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine. New England Journal of Medicine, 384(5), 403-416. doi:10.1056/NEJMoa2035389
Barron, E., et al. (2020). Associations of type 1 and type 2 diabetes with COVID-19-related mortality in England: a whole-population study. The lancet. Diabetes & endocrinology, 8(10), 813-822. doi:10.1016/S2213-8587(20)30272-2
Cai, Q., et al. (2020). Obesity and COVID-19 Severity in a Designated Hospital in Shenzhen, China. Diabetes Care, 43(7), 1392-1398. doi:10.2337/dc20-0576
Caussy, C., et al. (2020). Prevalence of obesity among adult inpatients with COVID-19 in France. Lancet Diabetes Endocrinol, 8(7), 562-564. doi:10.1016/s2213-8587(20)30160-1
CDC. (2020). National Diabetes Statistics Report, 2020. Retrieved from Atlanta GA: https://www.cdc.gov/diabetes/data/statistics-report/index.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fdiabetes%2Fdata%2Fstatistics%2Fstatistics-report.html
CDC. (2021). Defining Adult Overweight and Obesity. Retrieved from https://www.cdc.gov/obesity/adult/defining.html
Clark E., etc. (2020) Disproportionate impact of the COVID-19 pandemic on immigrant communities in the United States. PLoS Negl Trop Dis 14(7): e0008484. https://doi.org/10.1371/journal.pntd.0008484
Dietz, W., et al. (2020). Obesity and its Implications for COVID-19 Mortality. Obesity, 28(6), 1005-1005. doi:https://doi.org/10.1002/oby.22818
Dispinseri, S., et al. (2021). Robust neutralizing antibodies to SARS-CoV-2 develop and persist in subjects with diabetes and COVID-19 pneumonia. The Journal of clinical endocrinology and metabolism, dgab055. doi:10.1210/clinem/dgab055
Docherty, A. B., et al. (2020). Features of 20?133 UK patients in hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: prospective observational cohort study. BMJ (Clinical research ed.), 369, m1985-m1985. doi:10.1136/bmj.m1985
Food and Drug Administration. (2020a). Vaccines and Related Biological Products Advisory Committee Meeting FDA Briefing Document Pfizer-BioNTech COVID-19 Vaccine. Retrieved from https://www.fda.gov/media/144245/download
Food and Drug Administration. (2020b). Vaccines and Related Biological Products Advisory Committee Meeting FDA Briefing Document Moderna COVID-19 Vaccine. Retrieved from https://www.fda.gov/media/144434/download
Food and Drug Administration. (2020c). Vaccines and Related Biological Products Advisory Committee Meeting FDA Briefing Document Janssen Ad26.COV2.S Vaccine for the Prevention of COVID-19. Retrieved from https://www.fda.gov/media/146217/download
Frasca, D., et al. (2020). Effects of obesity on serum levels of SARS-CoV-2-specific antibodies in COVID-19 patients. medRxiv, 2020.2012.2018.20248483. doi:10.1101/2020.12.18.20248483
Gao, F., et al. (2020). Obesity Is a Risk Factor for Greater COVID-19 Severity. Diabetes Care, 43(7), e72-e74. doi:10.2337/dc20-0682
Gregory, J. M., et al. (2021). COVID-19 Severity Is Tripled in the Diabetes Community: A Prospective Analysis of the Pandemic’s Impact in Type 1 and Type 2 Diabetes. Diabetes Care, 44(2), 526. doi:10.2337/dc20-2260
Huang, I., et al. (2020). Diabetes mellitus is associated with increased mortality and severity of disease in COVID-19 pneumonia – A systematic review, meta-analysis, and meta-regression. Diabetes & Metabolic Syndrome: Clinical Research & Reviews, 14(4), 395-403. doi:https://doi.org/10.1016/j.dsx.2020.04.018
Kalligeros, M., et al. (2020). Association of Obesity with Disease Severity Among Patients with Coronavirus Disease 2019. Obesity, 28(7), 1200-1204. doi:https://doi.org/10.1002/oby.22859
Kavanagh, A., et al. (2020). Improving health care for disabled people in COVID-19 and beyond: Lessons from Australia and England. Disability and Health Journal, 101050. doi:https://doi.org/10.1016/j.dhjo.2020.101050
Khatana, S. A. M., etc. (2020) Health Disparities and the Coronavirus Disease 2019 (COVID-19) Pandemic in the USA. J Gen Intern Med, 35(8), 2431-2432. doi: 10.1007/s11606-020-05916-w
Kuy, S., et al. (2020). Focusing on Vulnerable Populations During COVID-19. Academic medicine : journal of the Association of American Medical Colleges, 95(11), e2-e3. doi:10.1097/ACM.0000000000003571
Li Volti, S., et al. (1998). Hyporesponsiveness to intradermal administration of hepatitis B vaccine in insulin dependent diabetes mellitus. Archives of disease in childhood, 78(1), 54-57. doi:10.1136/adc.78.1.54
Lighter, J., et al. (2020). Obesity in Patients Younger Than 60 Years Is a Risk Factor for COVID-19 Hospital Admission. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 71(15), 896-897. doi:10.1093/cid/ciaa415
Liu, K., et al. (2020). Clinical features of COVID-19 in elderly patients: A comparison with young and middle-aged patients. Journal of Infection, 80(6), e14-e18. doi:https://doi.org/10.1016/j.jinf.2020.03.005
Lone, S. A., et al. (2020). COVID-19 pandemic – an African perspective. Emerging Microbes & Infections, 9(1), 1300-1308. doi:10.1080/22221751.2020.1775132
McGurnaghan, S. J., et al. (2021). Risks of and risk factors for COVID-19 disease in people with diabetes: a cohort study of the total population of Scotland. The Lancet Diabetes & Endocrinology, 9(2), 82-93. doi:https://doi.org/10.1016/S2213-8587(20)30405-8
Muniyappa, R., et al. (2020). COVID-19 pandemic, coronaviruses, and diabetes mellitus. American Journal of Physiology-Endocrinology and Metabolism, 318(5), E736-E741. doi:10.1152/ajpendo.00124.2020
Painter, S. D., et al. (2015). The weight of obesity on the human immune response to vaccination. Vaccine, 33(36), 4422-4429. doi:10.1016/j.vaccine.2015.06.101
Palaiodimos, L., et al. (2020). Severe obesity, increasing age and male sex are independently associated with worse in-hospital outcomes, and higher in-hospital mortality, in a cohort of patients with COVID-19 in the Bronx, New York. Metabolism: clinical and experimental, 108, 154262-154262. doi:10.1016/j.metabol.2020.154262
Pellini, R., et al. (2021). OBESITY MAY HAMPER SARS-CoV-2 VACCINE IMMUNOGENICITY. medRxiv, 2021.2002.2024.21251664. doi:10.1101/2021.02.24.21251664
Petrilli, C. M., et al. (2020). Factors associated with hospital admission and critical illness among 5279 people with coronavirus disease 2019 in New York City: prospective cohort study. BMJ (Clinical research ed.), 369, m1966-m1966. doi:10.1136/bmj.m1966
Polack, F. P., et al. (2020). Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. New England Journal of Medicine, 383(27), 2603-2615. doi:10.1056/NEJMoa2034577
Popkin, B. M., et al. (2020). Individuals with obesity and COVID-19: A global perspective on the epidemiology and biological relationships. Obesity reviews : an official journal of the International Association for the Study of Obesity, 21(11), e13128-e13128. doi:10.1111/obr.13128
Rottoli, M., et al. (2020). How important is obesity as a risk factor for respiratory failure, intensive care admission and death in hospitalised COVID-19 patients? Results from a single Italian centre. Eur J Endocrinol, 183(4), 389-397. doi:10.1530/eje-20-0541
Simonnet, A., et al. (2020). High Prevalence of Obesity in Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) Requiring Invasive Mechanical Ventilation. Obesity, 28(7), 1195-1199. doi:https://doi.org/10.1002/oby.22831
WHO. (2020). Obesity and overweight. Retrieved from https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight#:~:text=In%202016%2C%20more%20than%201.9%20billion%20adults%20aged%2018%20years,women)%20were%20obese%20in%202016.
Yang, J., et al. (2021). Obesity aggravates COVID-19: A systematic review and meta-analysis. Journal of Medical Virology, 93(1), 257-261. doi:https://doi.org/10.1002/jmv.26237
Yelin, I., et al. (2021). Associations of the BNT162b2 COVID-19 vaccine effectiveness with patient age and comorbidities. medRxiv, 2021.2003.2016.21253686. doi:10.1101/2021.03.16.21253686
Zaki, N., et al. (2020). Association of hypertension, diabetes, stroke, cancer, kidney disease, and high-cholesterol with COVID-19 disease severity and fatality: A systematic review. Diabetes & metabolic syndrome, 14(5), 1133-1142. doi:10.1016/j.dsx.2020.07.005
Zhang, F., et al. (2020). Obesity predisposes to the risk of higher mortality in young COVID-19 patients. J Med Virol, 92(11), 2536-2542. doi:10.1002/jmv.26039