July 21, 2021 – People with sickle cell disease face 4 times as much risk of hospitalization and twice as much risk of dying from COVID-19, according to a big-data analysis from the United Kingdom.

Even those who carry just one copy of the sickle cell gene ― the carrier status for sickle cell disease ― appeared to be at heightened risk for these outcomes, report Ashley K. Clift, a clinical research fellow at the University of Oxford in the United Kingdom, and colleagues. The results were published online July 20 in Annals of Internal Medicine. .

"Our data suggest that people living with sickle cell disorders are a group at higher risk from this infection, and this is important from a public health perspective in terms of vaccination strategies and advice on nonpharmacological interventions," he says.

"The best course of action for managing risk in this group is vaccination," says Enrico M. Novelli, MD, director of the adult sickle cell program at the University of Pittsburgh Medical Center. Novelli was not involved in the study.

"To date, there are no specific studies of the effect of COVID-19 vaccination in patients with SCD, but there is no reason to believe it would be less effective or more risky."

Common-sense measures, such as wearing masks and physical distancing, particularly at large, indoor gatherings, should be encouraged, Novelli says. Keeping SCD under good control with available treatments is also important.

"Any patient with SCD who contracts COVID-19 should undergo close, outpatient monitoring with pulse oxygen measurements. If sick, they should be hospitalized in a center familiar with the care of SCD patients."

The U.K. results are in line with and expand on earlier evidence, but the association with sickle cell trait has been unclear and is notable, Clift said.

"The finding of the association with sickle cell trait is somewhat unexpected," pediatric hematologist/oncologist Rabi Hanna, MD, director of pediatric bone marrow transplantation at Cleveland Clinic Children's, says. "But I would question the accuracy of the numbers, since not all people with the trait realize they have it."

Study Details

The study involved 5,059 people with sickle cell and 25,682 people that carry just one copy of the trait. Among adults with SCD, 40 were hospitalized with COVDI-19 and 10 died.. Among those with just the sickle cell trait, 98 were hospitalized and 50 died. No children died, and only a few required hospitalization.

Because sickle cell disease affects 8 to 12 million people around the world ― 100,000 in the United States ― the authors say their results are important for policymakers and for vaccination prioritization. They also note that people who carry the trait carriers may be underdiagnosed.

"While SCD is part of newborn screening, there may be undiagnosed older people with the trait in the general population," Clift said. "But now we have these results, it's not that surprising that sickle cell trait is also associated with increased risk, albeit to a lower extent. This could suggest an almost dose-like effect of the sickle mutations on COVID hospitalization risk."

Neonatal screening for the most common form of sickle cell disease is mandatory in the United States, but the CDC has no clear data on how many people are aware they are carriers, Hanna said. "The states didn't all begin screening at the same time ― some started in the 1990s, others started in the 2000s ― so many young adults may be unaware they have the trait."

Clift said sickle cell disease affects many organs and cause heart and immune-system problems, it which may contribute to the greater risk for those infected with the coronavirus.

The message to patients and doctors is twofold, Hanna says: "SCD patients are at higher risk of COVID complications, and these are preventable with vaccination."