A large U.S. study looking at whether vaccination protects against long COVID showed the shots only offer minimal protection. Being vaccinated appeared to reduce the risk of lung and blood clot disorders but did little to protect against most other symptoms.
Compared to an unvaccinated individual, the risk of long Covid in a fully vaccinated individual was cut by only about 15 percent, the study found.
“The vaccines are miraculous at doing what they were designed to do,” that is, prevent hospitalization and death, said Dr. Ziyad Al-Aly, a clinical epidemiologist at Washington University in St. Louis and the lead author of the study. But they “offer very modest protection against long Covid,” he said.
The new paper, published Wednesday in Nature Medicine, is part of a series of studies by the Department of Veterans Affairs on the impact of the coronavirus, and was based on 33,940 people who experienced breakthrough infections after vaccination.
The data confirms the large body of research that shows vaccination greatly reduces the risk of death or serious illness. But there was more ambiguity regarding long covid.
The greatest benefit appeared to be in reducing blood clotting and lung complications. But there was no difference between the vaccinated and unvaccinated when it came to longer-term risks of neurological issues, gastrointestinal symptoms, kidney failure and other conditions.
“This was disappointing,” said Ziyad Al-Aly, lead author and chief of research and development service at VA Saint Louis Health Care System. “I was hoping to see that vaccines offer more protection, especially given that vaccines are our only line of defense nowadays.”
“Long covid” refers to the constellation of symptoms that many people have reported months after their initial infections.
Dr. Greg Vanichkachorn, director of the Mayo Clinic’s Covid Activity Rehabilitation Program in Rochester, Minnesota, who was not involved with the new study, said the results were not “too surprising.”
“We know that the majority of folks with long Covid have not had severe infections,” he said.
The study looked at national health care data from the U.S. Department of Veterans Affairs and included medical records of nearly 34,000 vaccinated people who had breakthrough Covid infections and more than 113,000 who were unvaccinated when infected with Covid from January 2021 through October 2021.
People were considered fully vaccinated if they had received two doses of either the Pfizer-BioNTech or Moderna vaccine or a single dose of the Johnson & Johnson vaccine.
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