If you’ve had COVID, watch out for stroke symptoms, by Faye Flam

Harlan Krumholz, a cardiologist at the Yale School of Medicine, says he worries about two kinds of long COVID. There’s the obvious version where people suffer prolonged virus symptoms like fatigue, and a stealthier version in which people recover yet carry an added risk of blood clots and strokes.

He doesn’t want to panic people — most of us will probably be fine. But new studies confirm that some will develop an elevated risk of blood clots, strokes or heart attacks. Given that most people have had COVID by now, everyone should be more vigilant about the early warning signs such as chest pain, unusual swelling, numbness or weakness, or sudden changes in balance, speech or vision.

Scary reports started to surface in the spring of 2020 of young people suffering deadly strokes during or right after a COVID infection. Doctors were starting to suspect COVID was not just a respiratory disease but a blood vessel disease. Larger studies now back up their suspicions and showed that COVID infections elevated everyone’s risk. That explained why younger people who should have had almost no risk were showing up with strokes, but they were just the tip of the iceberg. Patients who already smoked or had high blood pressure or diabetes went from high risk to even higher.

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One recent study, published in the journal Heart — associated with the British Medical Journal — tracked 54,000 people in the UK for four and a half months, and concluded that those who’d been infected were 2.7 times more likely to develop venous thromboembolism — a dangerous type of blood clot — than those who had never been infected.

The study also showed that those who got infected but were not sick enough to be hospitalized were still 10 times more likely to die of any cause during the study period than their uninfected counterparts. People who’d been hospitalized for COVID-19 were about 100 times more likely to die during the study period.

Another new study published in Neurosurgery focused on the period when people were actively infected, and concluded that COVID-19 infection was associated with strokes, and that strokes that occurred in infected people were likely to be more severe and harder to treat with surgery.

Krumholz, who I met before the pandemic through his work on improving the way doctors conduct and evaluate studies, said they still don’t have enough data to know how much these risks are mitigated by vaccination, or how long the elevated risk lasts. He said the medical community has long known that viruses can leave lingering effects, but until this pandemic, it had never been studied so thoroughly.

A consensus is forming that the lasting damage is caused by inflammation — a necessary part of our immune defense system, but one that can cause harm if it remains in high gear.

Not everyone who gets COVID will suffer serious blood vessel inflammation, but the disease is still something of a roll of the dice — or, as physician Ziyad Al-Aly puts it, Russian Roulette. That doesn’t mean people should despair or panic. Early treatment can save lives, which is why doctors urge people who’ve been infected not to ignore any warning sign, even if they weren’t previously at any known risk.

Al-Aly, who works at the Veterans Affairs St. Louis Health Care System, was one of the first doctors to jump into studying long COVID and, more generally, the aftermath of infection. “Something about SARS-CoV-2 increases propensity to damaging the lining of the blood vessels and increases the probability of blood clotting,” he said.

“What makes this such a dangerous disease is mainly that it attacks these vessels,” said Pascal Jabbour, a neurosurgeon at Thomas Jefferson Hospital in Philadelphia. The disease can lead to inflammation in blood vessels all over the body, he said, including the gut, causing a condition called bowel ischemia. It’s also at the root of a circulatory problem known as COVID toes.

Jabbour is lead author of the Neurosurgery paper. I’d interviewed in the spring of 2020, after he’d led one of a handful of very small studies showing preliminary but worrisome connections between strokes and COVID.

His newer research looks at 575 stroke patients — some with COVID and some without. They found those with COVID fared worse and were harder to treat with surgery aimed at opening blocked vessels. The infected group included younger, healthier people than the group of uninfected stroke patients, which is what you’d expect to see if infections were raising risk across the board.

Some in the infected group had mild infections, and a few didn’t know they had COVID until they showed up at the hospital with a stroke, Jabbour said. This further complicates the already complex task of tallying COVID deaths. Should people who appear to have had died of a stroke and tested positive be counted as dying with COVID, or from COVID?

Even something as neutral as heart disease risk is politicized when it intersects with the pandemic. “You can’t imagine the attacks I got,” said Jabbour, after he appeared on CNN in 2020 discussing his early observations and study results. That polarization has only deepened — with some people refusing to believe that COVID can have lasting effects, and others posting scare stories that the continued harsh lockdowns in China are part of a plan to triumph over the West as widespread long COVID collapses our work force.

The reality is some people have been devastated by COVID, even as most fully recover. It takes time, good studies and a lot of cases to get an understanding of the after-effects of infection, and that information is coming from countries that have seen the most cases. The take-home message is that even if you feel fine, past COVID infection is a cardiovascular risk factor, a little like elevated cholesterol. It’s not a reason to despair, but it’s a very good reason to be vigilant.

Faye Flam is a Bloomberg Opinion columnist covering science. She is host of the “Follow the Science” podcast.