Department of Research & Evaluation News

Before COVID-19 vaccines became available, people with Down syndrome were less likely to be diagnosed with COVID-19 than people without the condition, according to a study of more than 12,000 Kaiser Permanente Southern California members published on June 24, 2022, in The Journal of Infectious Diseases.

However, the study found that people with Down syndrome faced a 6-times-higher risk of being hospitalized due to COVID-19, and an even higher risk of dying from the disease, compared to those without Down syndrome.

“Our results highlight the need to pay particular attention to prevention, monitoring, and prompt treatment of COVID-19 in patients with Down syndrome,” said the study’s lead author Jennifer Ku, PhD, MPH, of the Kaiser Permanente Southern California Department of Research & Evaluation. “Promotion of COVID-19 vaccines is also really important for people with Down syndrome.”

Down syndrome is a genetic condition that often leads to mental disability and other health problems, including increased overall risk of infection.

“Due to problems with their immune system, people with Down syndrome are more susceptible to many infectious diseases and usually experience more severe outcomes from them,” said the study’s senior author Hung Fu Tseng, PhD, MPH, also of the Department of Research & Evaluation. “But whether this holds true for COVID-19 infection was unclear.”

First large study of Down syndrome and COVID-19

A small number of earlier studies had suggested a potential link between Down syndrome and COVID-19 severity. However, larger population-based studies had not been conducted.

To help determine a possible association, Dr. Ku and her colleagues compared COVID-19 diagnosis and severe outcomes between 2,542 people with Down syndrome and 10,164 without Down syndrome, who were matched on factors including age, race/ethnic groups, and sex. They used data from March through December 2020, before COVID-19 vaccines became widely available.

The researchers found that COVID-19 infection rates were 32% lower in people with Down syndrome than in people without. However, people with Down syndrome were 6 times more likely to be hospitalized for COVID-19 and had an even higher risk of dying from the disease.

“At first, we were surprised that the infection risk was lower for people with Down syndrome, but it makes sense when you consider that this group and their families and caregivers may have been taking greater precautions to avoid COVID-19 infection,” Dr. Ku said.

The precise reasons for increased risk of severe COVID-19 remain unknown, but the researchers said that immune system problems commonly found in people with Down syndrome are likely culprits. In addition, people with Down syndrome may have additional health problems that contribute to worse COVID-19 outcomes.

“The chromosomal alterations in people with Down syndrome could be associated with dysregulation of the immune system,” Dr. Tseng said. “Whether increased inflammatory markers detected in people with Down syndrome alters the response to COVID-19 infection or is part of the mechanism which determines disease severity is not yet established.”

Informing care at Kaiser Permanente and beyond

The researchers said that they were uniquely positioned to conduct this large-scale study because of Kaiser Permanente Southern California’s integrated health system.

“It’s a combination of a robust electronic health record and our long-term membership that allows us to closely follow patients over time,” Dr. Tseng said.

The CDC now lists people with Down syndrome as a priority group for vaccination. “Our findings are a really important contribution to the data informing that prioritization,” Dr. Ku said.

In general, future research into links between Down syndrome and COVID-19 and the effectiveness and safety of COVID-19 vaccines for these patients is important to inform vaccination policy.

In addition to Dr. Ku and Dr. Tseng, other authors on the study were Myron Levin, MD, of the University of Colorado, Aurora; and Ana Florea, PhD, MPH; I-Chun Lin, MD MPH, and Yun Tian, MS, of Kaiser Permanente Southern California Department of Research & Evaluation.