The coronavirus that has infected President Trump and killed more than 1 million people is a sneaky pathogen that uses its signature spikes to latch onto healthy cells and copy itself, creating little outward effect in some people but massive havoc in the lungs, heart and kidneys of others.
Even those who fend off the disease are seeing after-effects, from weakened heart muscles to diminished lung capacity, creating a legion of “long-haulers” who reel from the virus for months.
Scientists are still learning about the coronavirus that was first discovered in humans in Wuhan, China, in December, but 10 months of worldwide woe have taught us plenty.
Once a person is exposed, the virus latches onto a receptor, known as the ACE2, in healthy cells using the spikes that protrude from it (and which give it the “corona” moniker).
“The spike protein is like the key that goes into a receptor site, the lock, on a cell,” said William Schaffer, an infectious-disease specialist at Vanderbilt University. “That allows the virus to enter the cell and, once it’s there, all viruses attack the metabolism of the cell and redirect it to replicate the virus.”
Eventually, the cell opens up and millions of virus particles spill out, attacking other parts of the body.
Known as a respiratory disease, the new coronavirus tends to attack the lungs and cause shortness of breath.
President Trump, for instance, saw his blood oxygen levels drop and required supplemental oxygen twice.
But the virus can strike the body from head to toe, with doctors discovering damage to the heart and kidneys, in particular.
The virus can infect cells that line blood vessels, known as endothelial cells, and it has been found in the gastrointestinal (GI) tract and brain, said Dr. Daniel Kuritzkes, chief of the infectious-diseases divisions at Brigham and Women’s Hospital in Boston.
Many people who contract the coronavirus have reported losing their sense of taste or smell, making it a telltale sign of infection. It’s likely due to the virus’s impact on nerve endings.
Some patients report GI problems or cognitive problems, such as fogginess or confusion. Serious blood clots have been reported and fatigue, fever and muscle aches are common, yet there are plenty of people who do not develop any symptoms.
What proportion of cases remain asymptomatic is not clear, since those people are often not tested.
The virus tends to incubate for up to 14 days, with a median period of four to five days between exposure and the onset of symptoms, according to the Centers for Disease Control and Prevention.
The CDC cites a study saying 97.5% of people with COVID-19 saw symptoms within 11.5 days.
Scientists believe that COVID-19 deaths result from multiple factors — from high levels of the virus, including in the blood, to the immune system going into overdrive in what’s known as the “cytokine storm.”
“That’s calling in the Army, Navy and the Air Corps to focus on getting rid of the virus itself. But that response is often an over-response and you get collateral damage,” Dr. Schaffner said.
Doctors are using a steroid, dexamethasone, to tone down the inflammatory response. Mr. Trump received the drug over the weekend.
Age is considered a key factor in whether COVID-19 kills a patient. An early study from China found that 15% of people older than 80 who contracted the virus died from the illness, compared to 0.2% of those younger than 40.
People with no underlying conditions saw an overall fatality rate of 0.9% while more than 10% of those with heart disease, 7% of those with diabetes and 6% with respiratory disease or cancer succumbed to the virus.
Nursing homes are considered particularly vulnerable, since many residents are elderly and have medical conditions, or “comorbidities.”
Even if someone is released from the hospital, they’re typically not out of the woods.
“Many patients continue to suffer symptoms of COVID-19 for weeks to months after being diagnosed with COVID-19,” Dr. Kuritzkes said.
He pointed to a CDC study that found 94% of patients interviewed two to three weeks after testing positive had at least one symptom, such as fatigue, cough or shortness of breath.
Federal scientists are particularly worried about myocarditis, referring to inflammation of the heart muscle.
“The risk of heart damage may not be limited to older and middle-aged adults. For example, young adults with COVID-19, including athletes, can also suffer from myocarditis,” the CDC website says.
Dr. Schaffner said in Mr. Trump’s situation, he would want to do a periodic electrocardiogram to check on the commander-in-chief’s ticker.
“I hope he’s monitored closely, especially on his cardiac function,” he said.
Mr. Trump has noted that his wife, first lady Melania Trump, is younger than him and is handling the virus as expected, with milder symptoms. He also said that once the president recovers, he “may be immune” to COVID-19, as he challenges Americans to take the virus head-on and live their lives.
Scientists are still trying to get a sense of how much immunity a COVID-19 survivor has from the antibodies that naturally develop. There have been some reports of reinfection in survivors, though data is limited.