COVID-19 has killed nearly a quarter-million Americans so far, a staggering figure that exceeds our losses from the Vietnam and Korean conflicts and World War I combined. Vulnerable patients, such as the elderly and chronically ill, have up to a 25 percent chance of death if they get sick enough to be hospitalized, but the majority of patients with mild to moderate disease recover within two to three weeks.

However, a new syndrome persisting for months after the infection has cleared is now being reported by many patients, including some with mild initial symptoms. These COVID “long-haulers” experience ongoing muscle aches, fatigue, decreased endurance, dizziness and a constellation of cognitive symptoms, including slowed thinking, loss of concentration and decreased ability to focus, decreased immediate and short-term memory, headache, insomnia and problems with visual tracking (which can interfere with using a smart phone or computer). For some, this syndrome is bad enough to disable them from their jobs and seriously interfere with their daily lives. This cluster of problems suggests widespread involvement of the brain.

Since testing for the virus is negative after the initial illness in these cases, chronic infection is not the cause, but there are many other potential suspects. Severe COVID can cause oxygen levels to drop dangerously low, permanently damaging the brain. COVID can promote abnormal clotting of the blood, which may block blood flow to the brain, causing a stroke. Severe disease can also spark a kind of highly destructive super-inflammation (the cytokine storm), which can be deadly and can leave survivors with damage to the brain and other organs. In milder cases, the causes are less clear, but could include chronic inflammation, as is speculated to be the cause of the condition known as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which has been reported in patients after infection with a cousin of COVID-19, severe acute respiratory syndrome (SARS), as well as several other viral infections.

As COVID-19 is a new disease, we do not know how many patients will contract this chronic syndrome, though early studies suggest tens of thousands have already been diagnosed in the United States alone, and that 50 percent to 80 percent of COVID patients have at least one bothersome symptom three months after infection. We do not yet know if or when any of these patients might recover.

So, what should we then do? Fortunately, each of us has the power to protect ourselves from becoming a COVID long-hauler.

The solution is simple, and the song remains the same: Wear a mask, social distance and wash your hands; these measures could prevent up to 90 percent of new infections if universally followed. Vaccines are on the way, but even after they are released, it will be several months until we achieve enough population immunity for us to be confident such precautions are no longer needed. Until then we must use the very effective tools already at hand. The brain you save may be your own.

Dr. Clifton L. Gooch is chair of neurology at USF Health and is vice president of research at Tampa General Hospital. He wrote this exclusively for the Tampa Bay Times.