Vaccines Are Effective Against Long COVID: Study

Lisa O'Mary

December 07, 2022

Editor's note: Find the latest long COVID news and guidance in Medscape's Long COVID Resource Center.

Getting at least one dose of a COVID-19 vaccine decreases the chances of having symptoms beyond 3 weeks or developing long COVID, a new analysis shows.

When compared to people who got no vaccine at all, a single dose of Pfizer, Moderna, AstraZeneca, or the Janssen vaccine was 29% effective at preventing long COVID. The protection was strongest (35% effective) for those who were vaccinated before being infected with the coronavirus. Post-infection vaccination also helped (27% effective).

Since the analysis "showed a significant reduction of post-COVID-19 conditions with the vaccine even after having COVID-19, vaccine should be offered to unvaccinated individuals who have had COVID-19," the authors wrote.

The study was published this week by Cambridge University Press in the journal Antimicrobial Stewardship & Healthcare Epidemiology. Researchers analyzed data for 1.6 million people from 10 studies published from December 2019 to April 2022. The studies they selected evaluated COVID-19 vaccine effectiveness by comparing outcomes for vaccinated and unvaccinated people. Specifically, the researchers looked at how many people had symptoms present 3 or more weeks after having COVID-19.

"The most common symptoms were fatigue or muscle weakness, muscle pain, anxiety, impaired memory, sleep difficulties, and shortness of breath," according to a summary of the analysis.

Up to 23 million people in the United States are believed to have long COVID, according to the US Department of Health and Human Services. Among people who have been infected with COVID-19, the CDC estimates that 13.3% have symptoms for a month or longer, and 2.5% have symptoms for 3 months or longer. Long COVID was included in protections under the Americans With Disabilities Act starting in July 2021.

The study authors cautioned that their findings have limits and said that they could not evaluate the effectiveness of vaccines for long COVID among people with weakened immune systems because of a lack of data. A more standardized definition of long COVID is needed "for research and clinical purposes," they wrote.

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