Breakthrough COVID-19 Infections More Likely in Cancer and Alzheimer’s Patients, study reveals

Two new studies conducted by the scientists at the Case Western Reserve University School of Medicine have found that breakthrough COVID-19 cases resulting in hospitalisations and deaths are significantly more likely in cancer and Alzheimer’s patients. The findings of the first study were published in the Journal of the American Medical Association (JAMA) Oncology. The first study analysed the electronic health records to track the number of breakthrough COVID-19 infections, hospitalisations, and mortality rates among vaccinated patients with cancer.

According to the researchers, the people with these diseases are often more susceptible to infection in general and are among the population’s most vulnerable to severe health outcomes from COVID-19 infections as well. According to the Centers for Disease Control and Prevention (CDC), a “breakthrough infection” occurs when a fully vaccinated person contracts COVID-19.

The team of scientists tracked people diagnosed with the 12 most common types of cancer: lung, breast, colorectal, bladder, liver, endometrial, skin, prostate, thyroid, and blood cancers. 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.

Moreover, 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 also analysed the records of more than 636,000 vaccinated patients, including more than 45,000 vaccinated people with cancer.

“This study showed significantly increased risks for COVID-19 breakthrough infection in vaccinated patients with cancer, especially those undergoing active cancer care, with marked variations among specific cancer types,” said Rong Xu, professor of biomedical informatics at the School of Medicine and coauthor of this study.

The researchers discovered that the overall risk of breakthrough COVID-19 infections in vaccinated people with cancer was 13.6 percent, compared to 4.9 percent for vaccinated people without cancer. Additionally, the highest risk of breakthrough infections was in people with pancreatic cancer at 24.7 percent, liver cancer 22.8 percent, lung cancer 20.4 percent and colorectal cancer 17.5 percent. Meanwhile, the overall risk for hospitalization following a breakthrough infection, in study participants with cancer, was 31.6%, compared to a rate of 3.9 percent in those without cancer.

“Breakthrough infections in patients with cancer were associated with significant and substantial risks for hospitalizations and mortality. These results emphasize the need for patients with cancer to maintain mitigation practice, especially with the emergence of different virus variants and the waning immunity of vaccines,” said Xu and study coauthor, Nathan Berger, the Hanna-Payne Professor of Experimental Medicine at the School of Medicine.

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

While conducting the study, the researchers examined data on breakthrough COVID-19 cases in those with dementia because, while vaccines are effective, breakthrough infections are possible, and older adults with dementia were underrepresented in vaccine clinical trials.

The team of scientists also examined anonymous electronic health data from more than 262,847 adults 65 or older vaccinated between December 2020 and August 2021, and who didn’t have the infection before being vaccinated. Of that number, 2,764 people were diagnosed with Alzheimer’s disease; 1,244 with vascular dementia, 259 with Lewy body dementia, 229 with frontotemporal dementia, and 4,385 with mild cognitive impairment.

The researchers found that the vaccinated patients with dementia had an overall risk for breakthrough infections ranging from 10.3% for Alzheimer’s disease to 14.3 percent for Lewy body dementia, significantly higher than the 5.6 percent in the vaccinated older adults without dementia.

“Patients with dementia have a significantly higher rate of breakthrough COVID infections after vaccination than patients of the same age and risk factors other than dementia,” said Pamela Davis, the Arline H. and Curtis F. Garvin Research Professor at the School of Medicine.