COVID vaccine linked to kidney damage and respiratory infections in studies

Two large studies have shed light on the potential health risks of the COVID vaccine – but some experts are calling for caution in interpreting the results.

Recent research has linked the vaccine to a higher risk of kidney damage, as well as certain respiratory infections.

A Korean study published in the International Journal of Infectious Diseases examined the development of infectious diseases during and after the COVID-19 pandemic, as well as the impact of vaccines.

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“While flu-like illnesses declined sharply at the start of the pandemic, upper respiratory infections and common colds increased in 2023 and 2024, well above expected levels,” lead study author Jihun Song, Ph.D., of the Department of Biomedical Informatics, Korea University School of Medicine, told Fox News Digital.

“Most strikingly, whooping cough has increased more than 40-fold compared to historical trends.”

Recent research has linked the vaccine to a higher risk of kidney damage, as well as certain respiratory infections. (iStock)

“The key message is that respiratory infections in Korea have changed dramatically after the COVID-19 pandemic, and the trends differ depending on the disease. »

When researchers looked at the impact of the COVID vaccine, they found that people who received four or more doses were less likely to get flu-like illnesses and whooping cough, but more likely to get colds and other mild respiratory infections.

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“We did not expect to see such divergent associations with infectious disease type, where some infections (flu-like illness) decreased among vaccinated individuals, while others (the common cold) increased,” Song said. “These mixed associations likely reflect complex changes in immunity, behavior and healthcare utilization in the post-pandemic era.”

People who received four or more doses of the COVID-19 vaccine were less likely to get flu-like illnesses and whooping cough, but more likely to get colds and other mild respiratory infections, the researchers said. (AP Photo/Steve Helber, file)

Dr. Jacob Glanville, CEO of Centivax, a San Francisco biotechnology company, pointed out that the group that received the most vaccines was older, with an average age of 67, while the groups with fewer vaccines averaged between 37 and 47 years old.

“They have to do an age comparison (called controlling for confounding variables) and then run the analysis again,” Glanville, who was not involved in the study, told Fox News Digital. “Clearly, older people are going to the hospital more for colds and upper respiratory infections.”

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The researchers noted that because the study was observational, it does not prove that the vaccine caused the increase in infections, but only shows an association.

Additionally, older adults and people with chronic illnesses are more likely to receive booster doses, which may influence the results, Song noted.

Changes in “care-seeking behaviors” and medical utilization patterns pose another limitation, he said. “After years of reduced health care utilization, people may visit clinics differently than before, which affects diagnosis rates.”

In a recent study, COVID-19 vaccination was associated with a higher risk of acute kidney injury and dialysis within 1 year, although vaccinated people had lower rates of all-cause death. (iStock)

The researchers also did not collect immunological data – such as antibody levels or immune cell activity – meaning they could not say whether the effects were due to biological immune responses or outside factors.

“The results may be influenced by differences in age, underlying diseases and healthcare utilization among vaccinated and unvaccinated groups,” Song said.

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He stressed that the study does not mean people should avoid the COVID vaccine.

“Instead, it highlights the need to raise awareness of the increase in respiratory infections to encourage rapid diagnosis and appropriate preventive measures, (as well as) enhanced surveillance of respiratory pathogens, as the post-COVID landscape is fundamentally different from before,” Song said.

“While influenza-like illnesses declined sharply at the start of the pandemic, upper respiratory infections and colds increased in 2023 and 2024, well above expected levels,” said a researcher. (iStock)

“Our results should not be interpreted as evidence that the vaccine increases or decreases specific infections, but rather as indicators of population-level trends that require further research.”

In another recent study published in the International Journal of Medical Sciences, COVID-19 vaccination was associated with a higher risk of acute kidney injury and dialysis within 1 year, although vaccinated people had lower rates of all-cause death.

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Over 12 months, 15,809 vaccinated people developed acute kidney injury, compared to 11,081 unvaccinated people.

A total of 1,513 people received dialysis in the year following vaccination, compared to 697 unvaccinated people.

“Both risks were small in absolute terms, but the study is statistically well-controlled and there might be a real signal here,” Glanville told Fox News Digital.

“Other studies have shown that the risk of kidney disease from infection is much higher than from vaccination, which is counterintuitive,” he continued. “This deserves further investigation.”

The study also had limitations, the researchers acknowledged.

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These included gaps in the electronic health record data – it lacked information on vaccine doses and antibody levels, as well as details about kidney problems, other health problems and over-the-counter medications that can affect the kidneys.

Since this was a retrospective study and not a controlled trial, differences between groups may have influenced the results.

“Benefits and risks are reported in both studies.”

Hua Wang, associate professor of materials science and engineering at the University of Illinois Grainger College of Engineering, encourages people to be careful when interpreting data in this type of research.

“Both studies report both benefits and risks, so we should not simply highlight the potential negative effects of COVID-19 vaccination, as some news reports say,” said Wang, who was not involved in the studies.

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“One potential limitation of both studies is the lack of information on the fraction of participants diagnosed with SARS-COVID-2 virus in the vaccinated and unvaccinated groups,” the professor added. “The effect of the viruses themselves, as we know, could be significant.”

One expert pointed out that the group that received the most vaccines was older, with an average age of 67, while the groups that received the fewest vaccines averaged between 37 and 47 years old. (iStock)

Dr. Marc Siegel, Fox News senior medical analyst and author of the new book “The Miracles Among Us” (Fox News Books), also commented on the research.

“These are massive studies that in no way prove that COVID vaccines cause kidney problems or increase susceptibility to other respiratory infections, including the flu,” he told Fox News Digital.

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“However, the association found certainly merits further study and highlights that immune pump priming needs to be carefully monitored to account for potential effects.”

Siegel added: “It’s also entirely possible that the studies were biased if those who took the vaccine were already more prone to other infections or kidney problems.”