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 RECOVER study looked at how common Long COVID is in adults and children across the US. Researchers compared people who had COVID-19 to those who didn’t. They used data from 3 nationwide research networks that collect electronic health records (EHRs). Since there is no single definition for Long COVID yet, each network created its own working definition. These were based on earlier studies and symptoms that are commonly seen in people with Long COVID. Researchers then checked how many people had those symptoms between 1 and 6 months after having COVID-19. Findings were generally similar across the 3 networks. They found that about 4 out of every 100 children, and between 10 and 26 out of every 100 adults, developed Long COVID, depending on the definition of Long COVID used. The rates of Long COVID also changed over time, likely linked to new versions of the virus. Understanding how common Long COVID is and how this changes over time can help researchers learn who is most likely to get Long COVID.
This RECOVER study looked at the link between COVID-19 severity (how mild or serious the illness was) and the chance of developing an autoimmune disease. COVID-19 severity ranged from no symptoms to being in the hospital and needing a breathing machine. The study also looked at which types of autoimmune diseases were most common after having COVID-19. Autoimmune diseases happen when the body’s immune system attacks its own healthy cells by mistake. Researchers used electronic health records (EHRs) from 3 nationwide research networks to study people who had COVID-19 between April 2020 and April 2021. They found that the most common autoimmune diseases in both children and adults after having COVID-19 were thyroid disease, a skin condition called psoriasis, and a gut problem called inflammatory bowel disease. In adults, inflammatory arthritis and Sjögren’s disease (an autoimmune disease that causes dry eyes, dry mouth, and joint pain) were also common. In children, Type 1 diabetes and autoimmune diseases involving blood were also found. The study's main finding was that people who were more severely ill from COVID-19 had a higher chance of developing an autoimmune disease than those who were less sick. This means that people with more severe illness likely had stronger immune reactions to COVID-19. This study shows a strong relationship between having severe COVID-19 and developing an autoimmune disease after getting 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 whether people with Human Immunodeficiency Virus (HIV) are more likely to get Long COVID after having COVID-19. HIV is a virus that attacks the body’s immune system. Researchers used electronic health records (EHRs) from 2 nationwide research networks of people ages 21 and older who had COVID-19. They divided them into 2 groups: people with HIV and people without HIV. Researchers used 2 methods to find people in the groups who might have Long COVID. One used a computer system that looked for Long COVID symptoms in medical records. The other looked for official diagnosis codes that doctors enter when they think someone has Long COVID. They found that people with HIV may have a slightly higher risk of being diagnosed with Long COVID when looking for Long COVID symptoms in medical records. However, they found that there was no clear link between having HIV and receiving the official diagnosis code for Long COVID. This suggests that Long COVID may be missed in people with long-term health problems like HIV.
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 looked at whether children to young adults ages 21 and younger who had COVID-19 were more likely to have long-term kidney problems. Researchers reviewed the electronic health records (EHRs) of over 1.9 million children and young adults up to 20 years old. About 487,000 of them had COVID-19. They found that children and young adults who had COVID-19 were about 17% more likely to get a new kidney disease and about 35% more likely to get a more serious type of kidney disease. The risk of having worsening problems was high for children and young adults who already had kidney disease (about 15% more likely), or who had a kidney injury (about 29% more likely) when they were first sick with COVID-19. These findings are important because they suggest that doctors should closely monitor the kidney health of young patients after having COVID-19.
