Being overweight places you at increased risk from the coronavirus outbreak according to Professor Jean-François Delfraissy, who heads the scientific council advising the French government on the epidemic.

As many as 17 million of France’s 67 million citizens were seriously at risk from the coronavirus because of age, pre-existing illness or obesity. He adds that these factors mean that for the USA, “where the problem of obesity is well known,” the prospects are particularly grim.

Obesity has been identified as an independent risk factor associated with both morbidity and mortality for influenza (i.e. it makes it likelier to catch the disease and die from it), and a study on Chinese patients has found an association between higher BMI and mortality risk. Out of 17 patients who died during the study, 15 (88%) were classed as being overweight or more on the BMI scale, while only 18 of the 95 survivors (19%) were classed as overweight or above on the BMI scale.

One of the possible reasons is the strain placed by obesity on the body’s immune system. Writing for Aljazeera, Dr. Amir Khan, an NHS doctor and a senior university lecturer in the UK, explains that a high BMI places strain on the body that affects the function of the lymphoid and neutrophil line. This can weaken our immune response and leads to a “low level of chronic inflammation of normal tissue”.

Obese patients are also more difficult to transport and intubate, and he believes that “most healthcare systems are not well set up to manage patients with obesity”.

“This virus is terrible, it can hit young people, in particular obese young people. Those who are overweight really need to be careful,” Delfraissy told franceinfo radio.

He added that around 88% of all patients who were infected with the virus only showed flu-like symptoms and that mortality rates among young patients with severe cases were low — about 2%. However, this rate rose up to 14% for at-risk groups.

The country is still a long way away from achieving herd immunity — the French government is aiming for 50% to 60% of the population to be infected and recover, Delfraissy said. Still, progress is slow. It’s still much too early to end the country’s lockdown, which started March 17 and is set to last until at least April 15. For now, the council’s recommendation is for strict confinement measures to continue for the foreseeable weeks. Pressure on the country’s intensive care units (ICU) needs to ease, and the spread of the virus must be contained, before such measures may be lifted.

“Initial data show that the number of people who may have developed immunity is lower than we imagined, about 10-15%,” he explains.

A third condition for ending the lockdown was having sufficient stocks of equipment, Delfraissy adds, notably masks, testing kits, and tools for tracing infected patients.