These Vaccinated People Have a Higher Risk of Getting COVID, Studies Find
New research has pinpointed two groups of people most at risk for breakthrough COVID.
After nearly two months of relief, the coronavirus is back to circulating at heightened levels across the U.S. According to the Centers for Disease Control and Prevention (CDC), infections have increased by more than 18 percent in the last week while hospitalizations rose by over 24 percent. This uptick has been propelled by concerning Omicron subvariants, with the BA.2 and BA.2.12.1 variants each making up about half of the cases in the country right now, per the CDC. These subvariants are even more transmissible than the original Omicron, prompting continued warnings from virus experts about the need for widespread vaccination.
But with rising COVID cases and highly infectious variants, unvaccinated people are not the only ones at risk. According to the CDC, fully vaccinated individuals can still get infected with the virus because vaccines "are not 100 percent effective at preventing infection." These breakthrough infections are even more common now, rising up along with the Omicron surge, which also coincided with waning immunity from initial shots. In the state of Washington alone, the average number of COVID cases occurring among vaccinated people doubled during Omicron's reign in comparison to the Delta wave.
"Current vaccines protect against severe illness, hospitalizations, and deaths due to infection with the Omicron variant. However, breakthrough infections in people who are vaccinated can occur," the CDC says.
According to the agency, staying up-to-date on your COVID vaccines is the most effective way to curb your chances of developing a serious illness, even if you do get infected with the virus. But some vaccinated people are already more at risk for getting a breakthrough COVID infection than others.
Two recent studies from researchers the the Case Western Reserve University School of Medicine have found that vaccinated people who have cancer or dementia have a higher chance of getting infected with COVID.
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The first study, which was published April 8 in the Journal of the American Medical Association Oncology, looked at the rate of breakthrough cases among more than 45,000 vaccinated patients with cancer in the U.S. between Dec. 2020 and Nov. 2021. According to the study, the risk of breakthrough infections in patients with all types of cancer was 13.6 percent, while vaccinated people without cancer had a 4.9 percent risk.
The researchers for this study also broke down the likelihood for different types of cancer. According to the study, the highest risk for breakthrough COVID was in vaccinated people with pancreatic cancer at 24.7 percent, liver cancer at 22.8 percent, lung cancer at 20.4 percent, and colorectal cancer at 17.5 percent. Cancers with a lower risk included thyroid at 10.3 percent, endometrial at 11.9 percent, and breast at 11.9 percent.
The overall risk of hospitalization and death was also higher in vaccinated cancer patients, at 31.6 percent and 6.7 percent, respectively. In comparison, vaccinated patients without cancer only had a 3.9 percent chance of hospitalization and a 1.3 percent risk of death.
"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," study coauthors Rong Xu, PhD, a professor of biomedical informatics at the School of Medicine, and Nathan Berger, MD, the Hanna-Payne Professor of Experimental Medicine at the School of Medicine, said in a statement.
The second study, which was published April 13 in the Alzheimer's & Dementia journal, looked at the rate of breakthrough COVID for more than 262,000 vaccinated older adults between Dec. 2020 and Aug. 2021. According to the study, the overall risk of breakthrough infections for fully vaccinated patients with dementia ranged from 8.6 to 12.4 percent. Those most in danger were patients with Lewy body dementia (LBD) who had a 14.3 percent risk, followed by vascular dementia (VD) at 12.5 percent, frontotemporal dementia (FTD) at 11.8 percent, mild cognitive impairment (MCI) at 11.6 percent, and Alzheimer's disease (AD) at 10.3 percent. In comparison, those without dementia had a 5.6 percent risk.
"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," Pamela Davis, PhD, the Arline H. and Curtis F. Garvin Research Professor at the School of Medicine, said in a statement. "Therefore, continued vigilance is needed, even after vaccination, to protect this vulnerable population. Caregivers should consider ongoing masking and social distancing, as well as booster vaccines to protect these individuals."
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