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Long COVID rates are significantly higher in the South, Midwest, and West than in New England and the Northeast — with rates two to three times higher in some cases, a new federal study showed.

Some states with the highest long COVID prevalence also have some of the lowest rates of COVID vaccination, according to the survey conducted by the US Centers for Disease Control and Prevention (CDC). Conversely, some states with high vaccination rates also have low COVID rates.

Vermont, for instance, has the lowest long COVID rate in the nation, at only 4.2%, and also one of the highest vaccination rates in the United States — with more than 88% fully vaccinated and 54% having received a booster.

Other states with low long COVID rates and high vaccination rates include Massachusetts (5.3% long COVID rate, 82% fully vaccinated, 45% boosted); Maine (5.3% long COVID rate, 84% fully vaccinated, 49% boosted); Washington (5.2% long COVID rate, 75% fully vaccinated, 42% boosted); and Maryland (4.3% long COVID rate, 80% fully vaccinated, 43% boosted).

West Virginia’s long COVID rate is the highest in the nation, at 10.6%, and the state also has a low vaccination rate of only 59%. Only 29% received a booster dose.

Other states with high long COVID rates and low vaccination rates include Alaska (6.6% long COVID rate, 65% fully vaccinated, 31% boosted); Kentucky (7.5% long COVID rate, 60% fully vaccinated, 28% boosted); and Texas (6.5% long COVID rate, 64% fully vaccinated, 23% boosted).

The survey findings confirm that vaccination seems to play a large role in reducing long COVID risk, said David Smith, MD, chief of the Division of Infectious Diseases & Global Public Health at the University of California, San Diego.

“It doesn't surprise me that we have varying degrees of long COVID [across states],” he said. “Vaccination does seem to be somewhat helpful for when you do get COVID in that it decreases the risk of long COVID.”

Higher education and higher income may also influence long COVID rates. People in the South and Midwest have lower average incomes and levels of education than people in the Northeast or Pacific Northwest.

Lower education levels are associated with lower-income levels, and low-income Americans also tend to be more likely to smoke. Both increase the risk of developing a severe case of COVID, which may increase the risk of developing long COVID.

“There are some states that have higher obesity rates, higher diabetes rates, higher hypertension rates, etc., and all three of those factors are also associated with long COVID,” Smith said.

Rates May Be Declining

The new CDC survey comes as research suggests long COVID rates overall are declining across the United States. In late 2023, a study published in the journal PLOS ONE, which analyzed US Census Bureau survey data from 2022, found that 14% of nearly 500,000 Americans studied had long COVID symptoms.

According to the newer CDC survey, those percentages have declined nationwide, though prevalence still varies state to state.

In the PLOS ONE study, Texas, Ohio, and Arizona had estimated rates of 15.3%, 13.7%, and 16.6%, respectively. Those rates have since declined to 6.5%, 7.1%, and 7.1%, respectively, according to the latest CDC survey.

The new CDC study was a cross-sectional, population-based survey of adults aged 18 years or older. Long COVID was defined as symptoms lasting more than 3 months that were not present before COVID-19 infection. The survey included respondents from all 50 states, the District of Columbia, Guam, Puerto Rico, and the US Virgin Islands.

Overall, the study found long COVID prevalence to be higher in the South, Midwest, and West than in New England and the Pacific Northwest. Northeastern and Western states like Oregon, California, and New York had an estimated prevalence of 5.3%, 5.5%, and 5.4%, respectively.

Researchers said the fact that long COVID isn’t even a reportable illness has made tracking differences state-by-state over long periods difficult.

“You have to go other sources, such as surveys by telephone…to try to find what the occurrence is…there’s no single diagnostic test that tells you whether you have long COVID,” said William Schaffner, MD, an infectious disease specialist at Vanderbilt University School of Medicine, Nashville, Tennessee.

Almost every symptom related to long COVID — aches, pains, mental confusion, breathing, and lung conditions — could be caused by other illnesses, blurring the line between the actual prevalence and what’s reported in studies.

“Not every healthcare provider is keyed in on and comfortable making that diagnosis [of long COVID],” said Schaffner.

Disparities in Health Equity

Another complicating factor: Disparities in the US public health system. A recent report by the Commonwealth Fund, an independent healthcare research firm, found that among 10 high-income countries, the United States came in last in three categories: Healthcare equity, health outcomes, and access to care.

“If you don't have a good public health system that covers the have-nots, which means you also increase the risk of those other three conditions that I talked about…obesity, hypertension, and diabetes, then that increases the risk of long COVID,” Smith said.

Some high-risk areas with high incidences of long COVID also don’t have good healthcare infrastructure. “We have differences in populations in states regarding poverty, age distribution, and vaccination rates, all of those undoubtedly play a role in impacting the occurrence of long COVID,” said Schaffner.

Better Tools Still Needed

COVID rates aren’t tracked the same way they were during the height of the pandemic. The United States currently uses a mixture of CDC, state, and county health department data. This is in addition to wastewater testing to track viral levels.

Experts say studies of long COVID going forward need to have better tools to gather and interpret the data to reach more definitive conclusions.

“We will be helped if we get a more secure understanding of how COVID actually will initiate a pathophysiologic phenomenon in our bodies that actually result in long COVID. If we understood that better, I think we could get a better handle on long COVID and might even be able to develop a diagnostic test,” Schaffner said.