Post by Nadica (She/Her) on Sept 4, 2024 23:52:02 GMT
Study puts understanding of long COVID and vaccination into question - Published Sept 4, 2024
A new study from researchers at the Mayo Clinic suggests that being vaccinated against COVID-19 does little to prevent long COVID.
The findings contradict what has become conventional wisdom in the last 3 years—that vaccines offer a chance to significantly reduce the risk of long COVID, or new or persistent symptoms 3 months or more after infection, most likely by reducing the severity of infection.
Melanie Swift, MD, MPH, was the lead author of the study, which was published in Open Forum Infectious Diseases. She said despite the current thinking that vaccines reduce the risk of developing long COVID, she wasn’t surprised she found no association.
"A lot of the early literature on long COVID was really defining long COVID through patient surveys," Swift told CIDRAP News. Swift’s study instead relied on participants having received a long COVID diagnosis from a physician after having a documented case of post-vaccination COVID-19 infection.
6.9% developed long COVID
The study was based on the electronic records of 41,652 people aged 5 years or older with SARS-CoV-2–positive polymerase chain reaction (PCR) tests between February 2021 and December 2022 and a diagnosis of long COVID 30 days to 6 months following infection.
The average age of patients was 41 years, 55.2% were female, and 90.7% were White. At the time of initial infection, 9,744 (23.4 %) were vaccinated with two doses of mRNA COVID-19 vaccine, and 7,658 (18.4 %) had received more than two mRNA doses.
A total of 8.2% of patients required hospitalization for COVID-19, and most infections occurred during the Delta and Omicron eras (39.8% and 47.1%, respectively).
In total, 6.9% of patients were diagnosed as having long COVID, with no observed difference between unvaccinated patients, those vaccinated with two doses of an mRNA vaccine, and those with more than two doses.
Long COVID was associated with older age, female sex, and hospitalization for the initial infection. It was inversely associated with infection during the Omicron period, the authors wrote.
Swift said that vaccines still play a role in preventing long COVID. “If you don’t get COVID, you don’t get long COVID," she said. "It remains the most important medical tools in our arsenal by virtue of not getting COVID and severe COVID, but we can’t stop there and say ‘if you were vaccinated, you don’t have to worry about long COVID.’”
Confounding factors and health behaviors
Clifford Rosen, MD, a senior scientist at the MaineHealth Institute for Research, has reviewed studies on long COVID and vaccines. He said the current study may be skewed because of its sample size.
"It’s a small cohort that is relatively homogeneous and likely has different healthcare behavior than other EHR [electronic health record] studies," Rosen said. Instead, he said long COVID studies done based on Veterans Affairs (VA) data offer a more heterogenous cohort.
Ziyad Al-Aly, MD, chief of research and development at the VA St Louis Health Care System and a clinical epidemiologist at Washington University, has been behind most VA studies on long COVID.
He just published a review of evidence showing that vaccination reduces the risk of long COVID. While the effect size varies by 15% to 70%, there is an estimated average reduction of 40% to 50%, almost universally.
He said he found Swift’s study surprising and said it likely suffers from one main confounding factor: The type of patient who seeks out a long-COVID diagnosis likely uses healthcare and is vaccinated.
Al-Aly said vaccination may help reduce some clusters of long-COVID symptoms better than others. Fore maple, his work has shown a "profound effect in pulmonary symptoms of COVID, and less on metabolic effects on long COVID.”
Though more research needs be done on long COVID and vaccination, Al-Aly remains confident that vaccines play an important role in reducing the risk of long COVID.
A new study from researchers at the Mayo Clinic suggests that being vaccinated against COVID-19 does little to prevent long COVID.
The findings contradict what has become conventional wisdom in the last 3 years—that vaccines offer a chance to significantly reduce the risk of long COVID, or new or persistent symptoms 3 months or more after infection, most likely by reducing the severity of infection.
Melanie Swift, MD, MPH, was the lead author of the study, which was published in Open Forum Infectious Diseases. She said despite the current thinking that vaccines reduce the risk of developing long COVID, she wasn’t surprised she found no association.
"A lot of the early literature on long COVID was really defining long COVID through patient surveys," Swift told CIDRAP News. Swift’s study instead relied on participants having received a long COVID diagnosis from a physician after having a documented case of post-vaccination COVID-19 infection.
6.9% developed long COVID
The study was based on the electronic records of 41,652 people aged 5 years or older with SARS-CoV-2–positive polymerase chain reaction (PCR) tests between February 2021 and December 2022 and a diagnosis of long COVID 30 days to 6 months following infection.
The average age of patients was 41 years, 55.2% were female, and 90.7% were White. At the time of initial infection, 9,744 (23.4 %) were vaccinated with two doses of mRNA COVID-19 vaccine, and 7,658 (18.4 %) had received more than two mRNA doses.
A total of 8.2% of patients required hospitalization for COVID-19, and most infections occurred during the Delta and Omicron eras (39.8% and 47.1%, respectively).
In total, 6.9% of patients were diagnosed as having long COVID, with no observed difference between unvaccinated patients, those vaccinated with two doses of an mRNA vaccine, and those with more than two doses.
Long COVID was associated with older age, female sex, and hospitalization for the initial infection. It was inversely associated with infection during the Omicron period, the authors wrote.
Swift said that vaccines still play a role in preventing long COVID. “If you don’t get COVID, you don’t get long COVID," she said. "It remains the most important medical tools in our arsenal by virtue of not getting COVID and severe COVID, but we can’t stop there and say ‘if you were vaccinated, you don’t have to worry about long COVID.’”
Confounding factors and health behaviors
Clifford Rosen, MD, a senior scientist at the MaineHealth Institute for Research, has reviewed studies on long COVID and vaccines. He said the current study may be skewed because of its sample size.
"It’s a small cohort that is relatively homogeneous and likely has different healthcare behavior than other EHR [electronic health record] studies," Rosen said. Instead, he said long COVID studies done based on Veterans Affairs (VA) data offer a more heterogenous cohort.
Ziyad Al-Aly, MD, chief of research and development at the VA St Louis Health Care System and a clinical epidemiologist at Washington University, has been behind most VA studies on long COVID.
He just published a review of evidence showing that vaccination reduces the risk of long COVID. While the effect size varies by 15% to 70%, there is an estimated average reduction of 40% to 50%, almost universally.
He said he found Swift’s study surprising and said it likely suffers from one main confounding factor: The type of patient who seeks out a long-COVID diagnosis likely uses healthcare and is vaccinated.
Al-Aly said vaccination may help reduce some clusters of long-COVID symptoms better than others. Fore maple, his work has shown a "profound effect in pulmonary symptoms of COVID, and less on metabolic effects on long COVID.”
Though more research needs be done on long COVID and vaccination, Al-Aly remains confident that vaccines play an important role in reducing the risk of long COVID.