Patients who develop serious or fatal COVID-19 are disproportionately likely to have at least one major underlying health condition, such as diabetes, hypertension, obesity, cardiovascular disease, asthma, kidney disease, or chronic obstructive pulmonary disorder.
In some cases, the possible explanations for these links are obvious. Diabetes and obesity are associated with a weaker resistance to infections; a letter from Weill Cornell Medicine physicians published on April 17 in NEJM suggested that obesity, particularly in men, was associated with treatment requiring mechanical ventilation. Asthma and chronic obstructive pulmonary disorder involve reduced lung function, and a greater susceptibility to lung inflammation; moreover, patients with these disorders often use corticosteroid immune-suppressing drugs, which reduce immunity to respiratory infections. In general, any serious underlying medical condition can make a vital organ less able to withstand the biological stresses caused by an infection and resulting inflammation.
Some researchers have suggested that common treatments for high blood pressure and diabetes may worsen COVID-19 risk, based on the fact that these drugs can boost the levels of ACE2, a cell-surface enzyme that the COVID-19 coronavirus uses to get into cells. However, there is no clinical evidence that these drugs worsen risk, and doctors generally have not advised patients to stop taking them.
Many people take non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen for chronic conditions such as arthritis. These drugs are known to stress the kidneys when taken long-term and may even cause chronic kidney disease. That is potentially a problem in the context of COVID-19 because the infection often attacks the kidneys. Some intensive care specialists have observed unexpectedly severe cases of COVID-19 in people with histories of long-term NSAID use, Dr. Pelzman said.
Having an unusually weakened immune system, for example due to cancer treatments, organ transplants, or other conditions requiring patients to take immune-suppressing drugs, is another factor that may greatly increase the susceptibility to serious COVID-19 infection – and make people more contagious during infection. Doctors have been advising those with suppressed immune systems to be extra careful to avoid potential exposure to the virus, for example by staying home, and washing hands frequently.