A new UCLA Health study reveals that COVID-19 vaccination significantly reduces the risk of severe kidney damage among hospitalized patients, with unvaccinated individuals showing substantially higher rates of dialysis requirements and mortality.
Study Findings Show Clear Protection Against Kidney Injury
Researchers at UCLA Health analyzed electronic medical records from approximately 3,500 hospitalized patients aged 18 and older between March 2020 and March 2022. The study compared patients who received at least two primary doses of Moderna or Pfizer mRNA vaccines, or one dose of Johnson & Johnson Janssen vaccine, with unvaccinated hospitalized patients.
The results demonstrated that unvaccinated COVID-19 patients were 16% more likely to require continuous renal replacement therapy (CRRT) during their hospital stay compared to vaccinated patients. More striking was the post-discharge outcome: unvaccinated patients were more than two-and-a-half times as likely to need CRRT after leaving the hospital and faced a significantly higher risk of death following discharge.
"This nonstop dialysis is vital for patients in intensive care whose kidneys can no longer function properly," explained lead author Dr. Niloofar Nobakht, a nephrology professor at UCLA. CRRT performs the essential functions of damaged kidneys by continuously filtering waste from the blood, typically used in critical care settings.
COVID-19's Impact on Kidney Function
Previous research has established the significant kidney risks associated with COVID-19 infection. A 2021 Yale University School of Medicine study found that approximately 30% of hospitalized COVID-19 patients develop acute kidney injury, an abrupt but usually reversible form of kidney dysfunction. Patients hospitalized with COVID-19 were twice as likely to need dialysis compared to patients hospitalized for other reasons.
COVID-19 can damage kidneys either directly or indirectly through harm to other organs such as the heart and lungs, with disease severity being the primary factor in kidney injury. "Mild or asymptomatic infections rarely cause significant kidney harm," noted Yong Chen, a professor of biostatistics at the University of Pennsylvania who researches COVID complications.
Vaccination's Protective Mechanism
The protective effect of vaccination appears to work primarily through reducing disease severity rather than directly shielding kidney cells. "Vaccination protects kidneys mainly by preventing the severe forms of Covid that cause kidney injury," Chen explained. "While vaccines don't directly shield kidney cells, they blunt the systemic illness that otherwise leads to multi-organ failure."
Dr. F. Perry Wilson, associate professor at Yale University School of Medicine, emphasized this indirect protection: "Among people with Covid, I would expect that, all else being equal, the vaccinated group just has less severe disease and thus less kidney trouble."
Study Limitations and Expert Cautions
Despite the compelling findings, experts highlight important limitations. The study lacked comprehensive data on patients' baseline kidney function prior to COVID-19 infection, making it difficult to determine the full extent of vaccination benefits.
"It's unclear how well the kidneys were functioning before Covid, making it difficult to fully determine how much of the benefit was due to vaccination alone," said Dr. Scott Roberts, associate medical director of infection prevention at Yale School of Medicine.
Special Considerations for Vulnerable Populations
The research raises particular concerns for patients with glomerulonephritis, a kidney condition affecting the organ's filtering units. Dr. Jeffrey S. Berns, a nephrologist at the University of Pennsylvania, noted reports of both adults and children experiencing relapses or new onset of glomerulonephritis after COVID-19 infection and, in some cases, following vaccination.
The risk of post-COVID kidney complications is especially high for older adults and immunocompromised individuals, though this appears connected to initial infection severity rather than the virus itself.
Implications for Pediatric Patients
While the UCLA study focused on adults, children also face kidney risks from COVID-19. Chen's separate research showed that children with prior COVID infections had a 35% higher risk of developing new chronic kidney disease within six months.
As COVID-19 variants continue to circulate, experts note that acute kidney injury cases have decreased compared to the early pandemic years. "As more and more people got vaccinated and or had some degree of immunity from prior infection, disease severity was not as bad and AKI became much less common," Berns observed.
