This past week, I received a call from a former patient. Two years ago, she arrived at our hospital for emergency treatment of a stroke, caused by a blockage in a blood vessel supplying the left side of her brain. Thanks to recent advances in stroke treatment and systems of care that emphasize the importance of swift treatment to preserve brain function, she had a dramatic recovery.

But she was calling because her sister had developed symptoms of a stroke two days earlier. In the covid-19 era, both had been anxious about calling emergency services and about coming into the hospital. Unfortunately, the sister’s stroke progressed rapidly, and she died before we could arrange any medical attention.

In recent days, like most stroke and critical care neurologists around the country, my colleagues and I at Yale New Haven Hospital have been preparing to receive a tsunami of coronavirus patients, who require hospital admission often in critical condition. But we have also taken steps to make emergency treatments of routine illnesses — such as heart attacks or strokes — continuously available.

Despite all this, anecdotal observations reveal something none of us anticipated: Stroke admissions here have plummeted 60 to 80 percent of their usual volume over the past month. Initially, I was convinced that this statistic was a random, transient event that would not last. Now, I am not so sure.

Lulls in stroke admission in normal times last a day or two, not weeks and they will be seen in one center, not across the board. But in speaking with colleagues around the country, it is clear my medical center is not alone. Stroke volumes appear to be dropping almost everywhere, and the same may be true for heart attacks and other conditions. So I am a more than a little concerned.

In the coming months, we will need to make sure that these anecdotal reports are confirmed by evidence. And already, there are multiple efforts underway, many supported by the American Heart Association/American Stroke Association.

The first question to answer is whether there are actually fewer strokes occurring right now, or if patients are still having strokes but not coming to the hospital, as was suggested by the experience of my patient’s sister.

Using population-based samples, we can start to get at these questions. But we don’t have any strong reason to believe that fewer strokes are occurring. Stress and immobility — such as from a self-quarantine — can actually increase the frequency of these conditions. If fewer strokes are occurring, then we will really have to take a hard look at risk factors that may exist in daily life (and which we don’t normally focus on when thinking of stroke risk) that may now be muted.

The greater concern is that Americans are continuing to have strokes, but they are not calling 911 and not coming to the hospital. Individuals may assume that this is a bad time, or risky, to call an ambulance or be at the hospital. While stay-at-home guidance is a key element of diminishing the spread of covid-19, this would be the wrong decision if you are having stroke symptoms — including facial weakness, slurred speech, change in language or weakness in an arm or leg.

For emergencies, such as a stroke or heart attack, rescue squads are still on the clock and specialized stroke teams stand waiting at hospitals throughout the country. For stroke, time is brain, more time away from help can mean progression of a stroke, worse outcome and closing of a time-sensitive treatment window that can help patients recover without little or no damage.

To be clear — as in usual times, do not wait to get help if you suspect sudden symptoms of a stroke. The AHA/ASA’s Stroke Council Leadership has published emergency guidance for U.S. stroke centers during the covid-19 crisis. This guidance supports keeping stroke systems of care up and running, while using appropriate means to keep health-care workers and patients safe during evaluation and treatment in the emergency setting.

In my hospital’s neuroscience intensive care unit, we have developed contingency plans to allocate beds for emergency strokes. Hospitals around the country are doing the same. Patients should feel comfortable knowing that deployment of teams in dynamic, resource-limited environments is something that is long embedded in the practice of every stroke team.

It is true that we are in a crisis with covid-19, but our communities need not compound any suffering that might result as a consequence of not seeking prompt care for serious, but treatable, conditions such as stroke.

Kevin Sheth is chief of the division of neurocritical care and emergency neurology and associate chair of clinical research at the neurology department at Yale School of Medicine and Yale New Haven Hospital