The Times recently looked at data on deaths from all causes in 12 different countries and found that 36,000 more people have died over the past month than the total of official COVID-19 deaths in those countries. Not all of those people died at home, I’m sure, but it stands to reason that many did since normally doctors will have some sense of what caused someone’s death if they’re treating them in a hospital.

Why is it happening? What’s going on with these people that leaves them dead before EMTs arrive?

There are three theories floating around in the reporting today, each of which is either tragic or terrifying or both. Theory one: Fear. Simple human fear of getting infected with coronvirus is leading people with other serious medical conditions to avoid the hospital, with fatal results.

Stayc Simpson’s blood pressure readings are all over the place. Her heart rate is fluctuating wildly. After struggling with heart failure and coronary artery disease for 15 years, undergoing a double bypass, and living with an implanted pacemaker and defibrillator, she knows her numbers aren’t good. She’s really worried. But fears about infection with the novel coronavirus, and a terrifying recent experience in an emergency room, have her steadfastly refusing to return to the hospital.

It’s not just cardiac patients. Hospitals are reporting fewer stroke patients and fewer appendicitis cases too. Sometimes patients in distress do ultimately give in and call the ambulance and end up at the ER with unusually severe conditions, like a ruptured heart muscle. Of note, via Stat: “EMTs in New York City reported a quadrupling of house calls for cardiac symptoms between March 30 and April 5; in a majority of cases, the patients could not be revived.” It’s not just emergency care that’s being put off either. The Times reported this morning that people are avoiding routine vaccines for other infectious diseases because they don’t want to risk being infected with COVID by getting close to a doctor for the shot. It’s totally irrational that someone with a cardiac crisis would avoid the ER for fear of being killed by a more speculative threat like coronavirus, but that’s fear for you.

Those people aren’t being killed directly by coronavirus, though. They’re collateral damage, victims who might have lived if not for the contagion that’s deterring them from seeking care. What about people who are dying at home of the virus itself? That’s theory two, per this op-ed by a New York doctor: He describes many COVID patients falling victim to “silent hypoxia,” unaware that pneumonia is gradually progressing in their lungs. For days they have no trouble breathing even though their blood oxygen is dropping. By the time respiratory symptoms set in, their case is already advanced. Many doctors have described examples of coronavirus patients showing up at the hospital, unwell but functioning basically normally, and then turning critical almost in an instant. Is this why?

Patients compensate for the low oxygen in their blood by breathing faster and deeper — and this happens without their realizing it. This silent hypoxia, and the patient’s physiological response to it, causes even more inflammation and more air sacs to collapse, and the pneumonia worsens until oxygen levels plummet. In effect, patients are injuring their own lungs by breathing harder and harder. Twenty percent of Covid pneumonia patients then go on to a second and deadlier phase of lung injury. Fluid builds up and the lungs become stiff, carbon dioxide rises, and patients develop acute respiratory failure…

Silent hypoxia progressing rapidly to respiratory failure explains cases of Covid-19 patients dying suddenly after not feeling short of breath.

Reading that reminded me of the 30-year-old baseball coach in New Jersey who came down with COVID, eventually went to the hospital, was given medication and some oxygen, and sent home. Within two days he was feeling better. That night he went to bed and texted his wife (who was sleeping in another room) that he was struggling again. He was dead when she checked on him in the morning. If silent hypoxia is causing patients to steadily lose oxygen until a tipping point is reached and they crash, it may be that some of those crashes come on suddenly enough that they never actually make it to the hospital. The doctor who wrote the op-ed recommends that everyone buy an oximeter so that they can measure their blood oxygen if they contract the disease, as it’s the only way to know if hypoxia has begun before there are symptoms. If you have pneumonia, you want to treat it early. Treating it late is … not good.

Theory three is the scariest, the subject of three different stories I’ve seen today. What if coronavirus isn’t mainly a respiratory illness? What if it’s more of a circulatory illness? Many doctors are reporting freakish blood clotting in many COVID patients, to the point that they’re considering treating them with blood thinners prophylactically upon admission.

Autopsies have shown some people’s lungs fill with hundreds of microclots. Errant blood clots of a larger size can break off and travel to the brain or heart, causing a stroke or heart attack. On Saturday, Broadway actor Nick Cordero, 41, had his right leg amputated after being infected with the novel coronavirus and suffering from clots that blocked blood from getting to his toes…

The first sign something was going haywire was in legs, which were turning blue and swelling. Even patients on blood thinners in the ICU were developing clots — which is not unusual in one or two patients in one unit but is for so many at the same time. Next came the clogging of the dialysis machines, which filter impurities in blood when kidneys are failing and jammed several times a day…

Although there was no consensus on the biology of why this was happening and what could be done about it, many came to believe the clots might be responsible for a significant share of U.S. deaths from covid-19 — possibly explaining why so many people are dying at home.

A neurosurgeon in New York reports “a seven-fold increase in incidence of sudden stroke in young patients during the past two weeks,” all under the age of 50, all with either no symptoms or mild symptoms of coronavirus, and few with any underlying health problems. Another neurosurgeon in New York says he saw twice the usual number of patients since mid-March with large blood blockages in the brain, including five under the age of 49 with no risk factors for stroke, which he called “crazy.” “I’ve never seen any other viruses causing that,” said a third doctor about the prevalence of blood clotting in COVID patients. They have no idea right now why it’s happening.

But maybe it helps explain the silent hypoxia:

Meanwhile, Dr. Hooman Poor, a Mount Sinai lung specialist, found himself working a late shift with 14 patients on ventilators. The ventilator readings were not what he expected.

The lungs did not seem stiff, as is common in pneumonia. Instead, it seemed blood was not circulating freely through the lungs to be aerated with each breath.

If COVID is causing clogs in the circulatory systems of people who have it, that would potentially account for why so many deaths are sudden enough to happen before paramedics arrive.

In lieu of an exit question, here’s a fourth — and especially sad — possibility for why some are dying at home, related to the first one above. For some older people who suspect they’re already infected, fear of going to the hospital has nothing to do with the virus itself. The fear is of dying alone in isolation, away from their families. How many people like this patient and his family in Italy chose not to call the ambulance because they want to be together at the end, however risky that may be?