On May 26, 2022, researchers from Case Western Reserve School of Medicine report breakthrough COVID-19 cases resulting in infections, hospitalizations and deaths are significantly more likely in cancer and Alzheimer’s patients.

People with these diseases are often more susceptible to infection in general, the researchers explained, and are among the population’s most vulnerable to severe health outcomes from COVID-19 infections as well. The studies come as the U.S. total of COVID-19 deaths since the pandemic began surpassed 1 million.

The first study, published recently in Journal of the American Medical Association (JAMA) Oncology, analyzed electronic health records to track the number of breakthrough COVID-19 infections, hospitalizations and mortality rates among vaccinated patients with cancer. A “breakthrough infection” is when a fully vaccinated person contracts COVID-19, according to the Centers for Disease Control and Prevention (CDC).

The research team counted people diagnosed with the 12 most common types of cancer: lung, breast, colorectal, bladder, liver, endometrial, skin, prostate, thyroid and blood. These participants received COVID-19 vaccinations between December 2020 and November 2021 and had not previously been infected. The control group consisted of vaccinated participants without cancer.

The researchers compared breakthrough COVID-19 infections between cancer and non-cancer participants, matching for comorbidities, social determinants of health, age and gender, and other demographics. The team analyzed the records of more than 636,000 vaccinated patients, including more than 45,000 vaccinated people with cancer. The team found:

• The overall risk of breakthrough COVID infections in vaccinated people with cancer was 13.6%, compared to 4.9% for vaccinated people without cancer.
• The highest risk of breakthrough infections was in people with pancreatic cancer at 24.7%, liver cancer at 22.8%, lung cancer at 20.4% and colorectal cancer at 17.5%.
• Cancers with lower risk of breakthrough infections included thyroid (10.3%), endometrial (11.9%) and breast (11.9%).
• The overall risk for hospitalization following a breakthrough infection in study participants with cancer was 31.6%, compared to a rate of 3.9% in those without cancer.
• The risk of death was 6.7% following a breakthrough infection, compared to 1.3% in patients without cancer.

In a second, separate School of Medicine study, researchers analyzed electronic health data to examine the incidence rate of breakthrough COVID-19 infections in those diagnosed with some subtypes of dementia. The study was recently published in the journal Alzheimer’s & Dementia.

The researchers compared the overall risks of breakthrough infections in vaccinated patients with dementia to those without any cognitive impairment. Vaccinated patients with dementia had an overall risk for breakthrough infections ranging from 10.3% for Alzheimer’s disease to 14.3% for Lewy body dementia, significantly higher than the 5.6% in the vaccinated older adults without dementia.