The new strain of coronavirus has devastating effects for the elderly and vulnerable, but in recent weeks in the UK a 13-year-old boy, 21-year-old woman and 36-year-old NHS nurse – all thought to be perfectly healthy – have died.
One of the most troubling coronavirus trends to emerge in recent days is the deaths of so many young people who had no known underlying health conditions.
In Britain alone, they include a 13-year-old boy from Brixton in south London, 19-year-old chef Luca Di Nicola, 21-year-old Chloe Middleton and NHS nurse Areema Nasreen, 36.
Their deaths have stunned their families, who said each one was thought to be healthy and had never been diagnosed with any pre-existing conditions that would have made them vulnerable to Covid-19.
While the new strain of coronavirus appears to most seriously affect the elderly, experts in the US have been trying to find out why some healthy and younger people are dying – and they believe they have found some possible answers.
Dr Sanjay Gupta, a neurosurgeon and chief medical correspondent for CNN, said scientists and researchers are exploring whether some younger people are dying due to their genetic makeup.
He wrote: “One possibility is a gene variation in the ACE2 gene. ACE2 is an enzyme that attaches to the outer surface of cells in the lungs, as well as the heart.”
Coronavirus uses the enzyme to enter airway cells.
Dr Gupta pointed to a story by Science magazine, in which Dr Philip Murphy, of the US National Institute of Allergy and Infectious Diseases, said “variations in the ACE2 gene that alter the receptor could make it easier or harder for the virus to get into cells”.
Scientists involved in that study are analysing the DNA of patients who had serious cases of Covid-19 and no underlying health issues such as diabetes or heart or lung disease, and comparing it with the DNA of those with mild or no pre-existing disease at all.
Dr Gupta said another possible factor is that pulmonary surfactant – a fluid secreted by the cells of the tiny air sacs in the lungs – becomes depleted in Covid-19 patients.
The fluid helps the lungs to expand and contract normally, but when the supply is depleted that function is disrupted, the air sacs can collapse and it becomes much harder to breathe.
Dr Gupta wrote: “If you think of your lungs as a sponge, surfactant would be the detergent which would make them soft and pliable. Without surfactant, however, your lung becomes stiff and hard to squeeze.
“It may be why some patients continue to struggle even on a breathing machine.”
Researchers are also looking into the human immune system and how it responds to viruses and bacteria.
It is possible that a healthy immune system could lead to severe problems.
Dr Gupta wrote: “In some young, healthy people, a very reactive immune system could lead to a massive inflammatory storm that could overwhelm the lungs and other organs. In those cases, it is not an aged or weakened immune system that is the problem – it is one that works too well.”
Another possibility is some young people thinking they are healthy and invincible, and therefore taking fewer precautions or ignoring social distancing rules to prevent themselves from catching coronavirus.
Those people “have been exposed to much larger viral loads from the environment”, Dr Gupta added.
In the UK, the most seriously affected patients have been the elderly and vulnerable, according to Government statistics.
In its most recent update, on March 31, the Office for National Statistics wrote: “The vast majority of deaths involving COVID-19 have been among people aged 65 years and over (100 out of 108), with almost half (45) of these occurring in the over-85 age group.”