A Singapore study into the effects of Covid-19 on overweight Asians - the first of its kind, according to researchers - has found that they are more than three times as likely to be admitted to intensive care as their slimmer counterparts.
The study, by Singapore's National Centre for Infectious Diseases, looked at 91 Covid-19 patients under the age of 60 and found that those with a body mass index (BMI) of 25 or higher were 6.3 times more likely to need supplemental oxygen, 1.2 times more likely to need mechanical ventilation and 3.1 times more likely to be admitted to intensive care, although the intensive care finding was not statistically significant.
Previous studies in other countries have returned similar results, though most used a higher BMI threshold of 30 or above. A lower cut-off was used in Singapore as "it is known that Asian populations have higher disease risks at lower BMI thresholds, possibly due to variations in fat distribution and lipid metabolism", the researchers said.
In New York City, having a BMI of 30 or above - which is considered obese - was found to be the single biggest factor for hospital admission in Covid-19 patients, aside from age. A British study also found that obese men were more likely to die from the disease, while a French one linked having a BMI of 35 or higher with an increased need for mechanical ventilation.
The Singapore researchers, whose findings were published on May 8 by Oxford University Press, said that they had wanted to find out how being overweight affected a patient's experience of Covid-19 given that obesity has been associated with increased severity and mortality in past outbreaks of respiratory disease.
They concluded that when determining which patients are in the most urgent need of treatment, doctors treating those of Asian ethnicity should not underestimate the effect of being even slightly overweight to avoid "potentially adverse outcomes".
"A BMI of 25 is not obese but just overweight," said David Lye, a senior consultant and director at NCID's Infectious Disease Research and Training Office and one of the study's authors. "Doctors should consider this when assessing patients and look for symptoms and signs that may suggest complications such as chest pain or breathlessness, high or persistent fever, and the presence of a lung infection on a chest X-ray."
When patients of all age groups were taken into consideration, there were no significant differences in baseline characteristics or clinical outcomes linked to BMI - the differences only showed up in those under the age of 60.
Dr Jeremy Lim, an associate professor at the National University of Singapore's Saw Swee Hock School of Public Health, said this was probably because age is a more important risk factor than weight.
Separately, another team of researchers in Singapore looked at serum extracted earlier this year from 12 survivors of 2003's severe acute respiratory syndrome outbreak to see if the antibodies they developed can be used to treat Covid-19 patients - given how closely related the underlying viruses are.
The study found that the antibodies of Sars survivors do not protect against Covid-19 - yet the fact that the antibodies were present nine to 17 years after initial infection hints at how long protective immunity against a coronavirus can last.
"If immunity against Sars and Covid-19 behaves the same way, any vaccine developed for Covid-19 should reasonably be expected to offer protection for a similar length of time," said Dr Louis Tan, former chief operating officer of Singapore's Mount Elizabeth Novena Hospital.
This article was first published in South China Morning Post.
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