Discover what the latest science from the RECOVER Initiative means for our ability to understand, diagnose, prevent, and treat Long COVID.
This page contains descriptions of findings from RECOVER research studies. These descriptions use plain language and a format that is easy to understand.
If you want to learn more about the scientific discoveries described here, you can also browse and search the complete list of RECOVER Publications.
This RECOVER study looked at how sense of smell changed over time in people who had COVID-19. Researchers gave a “scratch-and-sniff” test to a large group of people about 2 years after they had COVID-19. This test, called the University of Pennsylvania Identification Test (UPSIT), checks whether people can smell certain odors. The study found that 8 out of 10 people who felt that they had lost or had changes in smell after having COVID-19 were in fact not able to smell the odors normally. Even two-thirds of the people who thought their sense of smell was completely normal had a weaker sense of smell than they realized. These findings show that a weaker sense of smell can be a common and lasting problem after COVID-19. Because changes in smell have been linked to memory and thinking problems in other conditions, this could mean that people with changes in smell from COVID-19 could be at risk for thinking and memory issues. Doctors should use special smell tests to point out smell loss that patients may not notice to help them understand their condition and its risks, like not being able to smell smoke or spoiled food.
This RECOVER study looked at how Long COVID symptoms change as people get older and how often those changes happen. Researchers compared younger adults (ages 18–59) and older adults (age 60 and older) who did and did not have COVID-19. They found that Long COVID was most common in people ages 40–59, and less common in those ages 70 and older. Among the participants ages 70 and older, symptoms like fatigue, pain, and hearing problems were less helpful in identifying Long COVID because they were also common in older people who had never had COVID-19. Instead, symptoms of Long COVID in older adults were more likely to include problems with smell and taste as well as stomach issues. This finding is important because it helps doctors know what to look for when diagnosing and treating Long COVID in older patients.
This RECOVER study looked at how social determinants of health (SDoH) affect the risk of developing Long COVID after getting COVID-19. SDoH are the living and working conditions that affect a person’s health, such as how safe a neighborhood is, access to education, and how easy it is to get healthcare. Between October 2021 and November 2023, RECOVER researchers studied adults from 33 states, Washington, DC, and Puerto Rico who recently had COVID-19. These adults filled out surveys about their social situations, health conditions, and pregnancy status. The researchers followed them for 6 months to see who developed symptoms of Long COVID. They looked at SDoH including money problems, not having enough food, level of education, problems getting health care, having friends or family for support, and where someone lives. Out of 3,787 participants, 418 people (about 11%) developed Long COVID. Researchers found that people with money problems, not enough food, less education, trouble getting healthcare, and little social support had a higher risk of experiencing Long COVID. The researchers suggest that future studies explore whether addressing SDoH-related needs can help lower the chance of developing long-term effects of COVID-19.
This paper builds on an earlier RECOVER study about Long COVID symptoms in school-age children (ages 6 to 11 years old) and teenagers (ages 12 to 17 years old). In this study, RECOVER researchers focused on two younger age groups that they did not study before, including infants and toddlers (ages 0 to 2 years old) and preschool-age children (ages 3 to 5 years old). The study compared symptoms in children who had COVID-19 in the past with those who never had it. Researchers created new tools to help figure out which young children were most likely to have Long COVID based on their age group and symptom patterns. The symptoms that were most likely to be signs of Long COVID in infants and toddlers were poor appetite for a long period of time, trouble sleeping, coughing, and stuffy nose. For preschool-age children, the most likely signs were daytime tiredness, sleepiness or low energy, and coughing. Children with these symptoms often had worse overall health, lower quality of life, and delays in development. The tools from this study can be used in future studies to better understand Long COVID in young children and develop ways to care for them. This study is important because it shows that Long COVID symptoms in young children are different from those in older children and adults.
This RECOVER study looked at how COVID-19 can impact people’s physical abilities. Researchers looked at 3 groups of adults in the RECOVER study: people who never had COVID-19, people who had COVID-19 in the last 3 months, and people who had COVID-19 more than 3 months ago. They wanted to know if people who had COVID-19 were more likely to have trouble with daily activities like walking, climbing stairs, or getting in and out of a chair compared to those who never had COVID-19. To measure physical ability, participants were asked to sit in a chair and stand up as many times as they could in 30 seconds. This study didn't find big differences in physical abilities between the groups, but those who had severe COVID-19 and long-lasting symptoms faced more challenges. This study is important because the findings show that COVID-19 may have long-term impacts on physical function.
This RECOVER study found that adults who had COVID-19 were more likely to develop a condition called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) compared to those who didn’t have COVID-19. ME/CFS can be very severe and similar to many forms of Long COVID. Even small amounts of effort can lead to days or weeks of physical and mental exhaustion in people with ME/CFS. Researchers studied about 13,000 RECOVER participants and found that 4.5% of people who had COVID-19 in the study later developed ME/CFS, while only 0.6% of those who didn't have COVID-19 got ME/CFS. These findings highlight the need for healthcare professionals to be aware that ME/CFS can develop after having COVID-19.
Scientists updated a prior RECOVER study to explore Long COVID symptoms reported by participants in the RECOVER-Adult Observational Cohort Study. They compared symptoms in people who had COVID-19 to those who did not have COVID-19 to find the symptoms that were most different. The updated study included 13,647 participants, compared to 9,764 in the original, and added 8 new symptoms based on patient and community feedback. Symptoms that were most different between people with and without COVID-19 include post-exertional malaise, fatigue, brain fog, dizziness, palpitations, smell or taste change, thirst, chronic cough, chest pain, shortness of breath, and sleep apnea. In addition, this research update classifies Long COVID symptoms into 5 groups of symptoms called clusters. The previous study focused on 4 clusters. This study update is important because it highlights the wide range of symptoms experienced by people with Long COVID. Understanding these symptoms will help researchers study Long COVID and look for treatments.
A RECOVER study looked at whether a person’s sex at birth affects their risk of developing Long COVID. To do this, researchers studied a large group of people enrolled in the RECOVER adult cohort. They found that females were more likely to have Long COVID symptoms than males. Among females, the risk of getting Long COVID changed based on age, pregnancy status while having COVID-19, and if they had gone through menopause. Researchers discovered that the risk of getting Long COVID was higher in females ages 40–54 years and females who had not gone through menopause. On the other hand, females who had already gone through menopause were not at a higher risk compared to males. More research is needed to understand why differences in sex at birth may put someone at higher risk of experiencing the long-term effects of COVID-19. Knowing this and understanding which hormones play a role in Long COVID risk could help researchers develop treatments and ways to prevent Long COVID.
This RECOVER study looked at 25 different blood tests to see if any of the tests could be used to tell if someone might have Long COVID. Long COVID is when someone feels sick for a long time after having COVID-19. Researchers took blood from people who did and did not have COVID-19. They took blood from both groups 6 months after they got infected or after they joined the study. Researchers found small differences between the blood of people in each group. People who had COVID-19 had slightly lower platelet counts (platelets help stop bleeding), a bit more sugar in their blood, and signs of possible kidney problems. But, these differences were very small and might not be very important in finding out if someone has Long COVID. The study found that none of the 25 blood tests could show if someone has Long COVID because the test results were too similar between people with Long COVID and those without it.
