Even though people with sickle cell disease have a much higher risk of serious illness or death if they develop COVID-19, a new study shows they’re also much less likely than those without the blood disorder to have gotten vaccinated against coronavirus.

Researchers at the University of Michigan found that completion of the initial COVID-19 vaccination dose was nearly two times lower for adults with sickle cell disease than others their age.

In teenagers and children over 5, who overall have lower rates of COVID-19 vaccination, those with sickle cell disease were far less likely than other young people to have gotten their doses by summer 2022, revealed the study published in the JAMA Network Open.

"It is essential to develop targeted interventions to increase COVID-19 vaccination among people with sickle cell disease," said principal investigator Sarah Reeves, from the varsity.

"This population is chronically underserved in healthcare and society, emphasising the importance of increasing the accessibility and acceptability of these vaccines," she added.

To produce the findings, the team linked individual-level data from the statewide sickle cell data collection programme and immunisation registry.

In all, they had records from 3,424 people over age 5 with sickle cell disease and 9.4 million Michiganders over age 5.

Their findings showed that of the 61 per cent of the people without sickle cell disease, only 33.5 per cent of those with sickle cell disease, had gotten at least the primary dose or doses of Pfizer, Moderna or Johnson & Johnson COVID-19 vaccines.

The very highest-risk group, those over 65, had the highest vaccination rates, at 74 per cent for those with sickle cell disease and 87 per cent for the general population. However, there are only 110 people with sickle cell disease in this age group due to a combination of early mortality and less comprehensive data for this age group.

In adults aged 18 to 64, the difference between the two groups was about the same as the overall average. Only 17 per cent of children aged 5 to 11 with sickle cell disease, and 31 per cent of their counterparts aged 12 to 17, had gotten even a primary series of COVID-19 vaccines.

The researchers had previously shown that these groups have a higher rate of hospitalisation and death with COVID-19, compared to young people without the disease.