Feb. 21, 2024 – People vaccinated against COVID-19 were significantly less likely to have long COVID during the first few years of the pandemic, a new study from Michigan shows.
The findings were published this week in the journal Annals of Epidemiology. Researchers analyzed data for 4,695 adults in Michigan, looking for people reporting COVID symptoms for more than 30 or more than 90 days after infection. They then looked at whether people had completed a full, initial vaccination series or not. Vaccinated people were 58% less likely than unvaccinated people to have symptoms lasting at least 30 days, and they were 43% less likely to have symptoms for 90 days or more.
The researchers did their study because previous estimates of how much vaccination protects against long COVID have varied widely due to different ways of doing the research, such as mixed definitions of long COVID or including a limited set of people in the unvaccinated comparison group. The researchers wrote that their study offers more certainty because the people who took part in it more widely represent the general population. All of the people in the study had lab test-confirmed infections of SARS-CoV-2 (the virus that causes COVID) between March 2020 and May 2022.
Among vaccinated and unvaccinated people combined, 32% of infected people said they had symptoms for at least 30 days, and nearly 18% said they had symptoms for 90 days or more, according to a summary of the study published by the Center for Infectious Disease Research and Policy at the University of Minnesota. The researchers compared vaccinated and unvaccinated people multiple ways and consistently showed at least a 40% difference in long COVID.
In 2022, 6.9% of U.S. adults self-reported that they had had long COVID, which researchers defined as symptoms for at least 3 months after testing positive or being diagnosed by a doctor, according to a report last week from the CDC. That report also showed that the states with the highest rates of long COVID in 2022 were Alabama, Montana, North Dakota, Oklahoma, Tennessee, West Virginia, and Wyoming. West Virginia had the highest rate of self-reported long COVID, at 10.6% of adults.
People with long COVID may have one or more of about 20 symptoms, including tiredness, fever, and problems that get worse after physical or mental effort. Other long-term signs are respiratory and heart symptoms, thinking problems, digestive issues, joint or muscle pain, rashes, or changes in menstrual cycles. The problems can be so severe that people may qualify for disability status.
About 8 in 10 U.S. adults got the initial round of COVID vaccines, but just 22% of people reported receiving the latest version that became available in the fall of 2023.
The authors of the Michigan study wrote that “COVID-19 vaccination may be an important tool to reduce the burden of long COVID.”