When emergency rooms began filling with people with COVID-19 in the spring, there was one group of extremely high-risk patients who were too afraid to go.
People with sickle cell disease frequently need emergency medical care, but during the height of the pandemic, many suffered at home from fear of exposure to the coronavirus. The consequences of that hesitation are only beginning to be known.
Emergency departments are "usually, unfortunately, our first access point when it comes to getting treated for pain and other complications" of the disease, Kyle Smith, 31, of Philadelphia, said. But "people with sickle cell disease were terrified to go, even though they were in desperate need of treatment for pain."
Smith was just a baby when he had his first complication from sickle cell disease. His spleen filled with blood and had to be surgically repaired. Since then, he said he has been in the hospital "hundreds and hundreds" of times.
That is not uncommon for people with the disease, which inherently puts them at risk for heart problems, infection, organ failure and debilitating pain.
It was strongly suspected that the disease, which primarily affects Black people, would make patients particularly vulnerable to serious complications from COVID-19.
"That's all I was hearing, people self-treating at home and delaying care because of fear," Smith said, acknowledging that he, too, was "100 percent" afraid for his own health and safety during the early months of the pandemic.
People with sickle cell disease were terrified to go into the emergency department, even though they were in desperate need of treatment for pain.
Delaying care, however, can have devastating consequences for people with sickle cell disease.
Even a fever can suggest a person has "an overwhelming bacterial infection because their spleens don't work well," Dr. Kim Smith-Whitley, director of the Comprehensive Sickle Cell Center at Children's Hospital of Philadelphia, said.
If patients "delay care for a fever associated with a bacterial illness, they could die," Smith-Whitley said.
Individuals with sickle cell disease have a genetic mutation that causes red blood cells to distort into a crescent moon, or sickle, shape. When that happens, the cells become sticky and clump together, unable to flow easily throughout the body. Small blood vessels become clogged to the point that tissue and organs are starved of oxygen.
That, in turn, can cause a variety of life-threatening complications — as well as extraordinary pain. Some have described the feeling as broken glass trying to move through veins, or twisting a rubber band on a finger until it turns blue.
Even pain should not be ignored, Smith-Whitley said. Sometimes, severe pain among people with sickle cell disease is associated with a condition called acute chest syndrome, a pneumonia-like illness.
Smith-Whitley said that, too, is a potentially fatal complication if left untreated.
A vulnerable population
Sickle cell disease is the most common inherited blood disorder in the U.S., affecting an estimated 100,000 Americans, according to the Centers for Disease Control and Prevention. Most of those individuals are of African descent.
Fear of contracting COVID-19 has been a real factor for many Americans, but perhaps more so for those living with sickle cell disease.
"If they do get sick, patients with sickle cell can deteriorate very quickly," Dr. Farzana Sayani, director of the Penn Comprehensive Sickle Cell Program at Penn Medicine in Philadelphia, said.
Historically, sickle cell patients are more susceptible to viral illnesses, such as the flu, Sayani said. That's because the spleen, which acts as a blood filter and plays a critical role in the immune system, is often damaged.
So far, individuals with sickle cell disease appear to have been largely spared in the COVID-19 pandemic, though it is unclear how many have been infected.
The only known registryfor people with sickle cell disease who have also contracted the coronavirus is being run by researchers at the Medical College of Wisconsin. Even the CDC uses the database.
Dr. Julie Panepinto, a professor of pediatrics and hematology at the Medical College of Wisconsin, said she and her colleagues started the database to collect information about how COVID-19 affects sickle cell patients.
"It's a completely new virus. We knew nothing about it," Panepinto said, adding that it's well-established that sickle cell patients are at risk to become sicker from any infection, compared to healthy individuals.
As of Sept. 21, the database has logged 347 patients. Sixteen of those patients have died. While it is not yet a true representation of all COVID-19 patients living with sickle cell disease, and not an apples-to-apples comparison to the general population, the information collected so far is striking.
"The death rate related to COVID-19 in our population we've collected data on seems to be higher than what's reported in the general population, especially for the average age of our population, which is down to age 24," Panepinto said.
What's more, children with sickle cell disease seem to be much more impacted by COVID-19 than otherwise healthy children.
"Almost 25 percent of children reported into the registry have moderate or severe or critical disease," Panepinto said. Most children in the U.S. with COVID-19 tend to be asymptomatic or have mild symptoms.
As winter approaches, doctors say it's critical that individuals with sickle cell disease get the flu vaccine to prevent infections.
"I feel strongly that people should continue to do the same things they were doing before the pandemic," Smith-Whitley said, adding that includes seeking a physician's advice when they're in need of emergency care.
The typical advice for everyone else stands, too: Wear a mask, keep physically distant and wash hands frequently.
This article originally appeared on NBCNews.com.