
People with weakened immune systems—most of whom were vaccinated—made up 4% of a random sample of more than 12 million people in England in 2023 yet represented 22% of both COVID-19 hospital admissions and deaths, according to new findings from the INvestigation oF cOvid-19 Risk among iMmunocompromised populations (INFORM) study.
European researchers and representatives from the pharmaceutical company AstraZeneca conducted a retrospective study using the electronic health records of participants aged 12 years and older from a random 25% sample of the English population from January to December 2023.
The results were published in the Journal of Infection.
Twice the risk of hospitalization
Over the study period, 11,200 COVID-19 hospitalizations and 2,330 deaths occurred in the study sample. Immunocompromised participants accounted for 4.0% of 12.1 million people included in the sample but made up 21.7% and 21.9% of COVID-19 hospitalizations and deaths, respectively.
Beyond three years since the start of the COVID-19 pandemic, immunocompromised individuals remain disproportionately impacted from COVID-19 despite increased vaccination.
The risk of severe COVID-19 was higher among immunocompromised than otherwise healthy people (adjusted incidence rate ratio [aIRR] for hospitalization, 2.04; aIRR for death, 1.69).
Immunocompromised participants were more likely to have received at least four doses of COVID-19 vaccine than their non-immunocompromised peers (72.6% vs. 29.8%). The aIRRs for COVID-related consultations with a general practitioner and accident and emergency visits were 2.26 and 3.02 for immunocompromised and non-immunocompromised people, respectively.
Of the immunocompromised subgroups, the risk of COVID-19 hospital admission was highest for recipients of a stem cell transplant in the 2 years before infection (aIRR, 19.18), followed by those who had a solid organ transplant in the 5 years before infection (aIRR, 6.53). Other groups with a threefold or higher risk than those without the immune-weakening condition included those with primary immunodeficiency, end-stage kidney disease or dialysis, or blood cancers.
"Beyond three years since the start of the COVID-19 pandemic, immunocompromised individuals remain disproportionately impacted from COVID-19 despite increased vaccination," the authors wrote. "These findings highlight a persistent need for additional COVID-19 interventions for immunocompromised populations."