Research Summaries

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 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.

This RECOVER study looked at electronic health records (EHRs) from almost 300,000 children and young adults ages 20 and younger who had COVID-19 and compared them to over 900,000 children and young adults who did not. Researchers wanted to find out if there was a higher chance of heart problems for children and young adults—a symptom of Long COVID in this age group—after they had COVID-19. They found that children and young adults who had COVID-19 were much more likely to have heart problems like high blood pressure, heart inflammation, chest pain, and a fast heartbeat. These increased risks were found in all children and young adults, whether they had a heart condition before getting COVID-19 or not. This study is important for doctors so they can check and treat children and young adults for heart problems after COVID-19.

This RECOVER study looked at the similarities and differences between Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) in electronic health records (EHRs). Both illnesses can make people feel exhausted for long periods of time. Researchers studied the EHRs of 6.5 million adults and found some similarities between people who had diagnoses of either Long COVID or ME/CFS. Problems like trouble breathing, feeling very tired, and difficulty focusing were seen in the EHRs of both people with Long COVID diagnoses and those with ME/CFS diagnoses. But there were also some differences. People with a diagnosis of Long COVID were more likely to have problems with their heart and lungs in their EHRs. People with a diagnosis of ME/CFS were more likely to have pain, trouble sleeping, and problems with mood or thinking in their EHRs. Researchers looked at the symptoms listed in people’s EHRs, regardless of diagnosis. They found that about half the people with symptoms that looked like Long COVID also had symptoms that looked like ME/CFS. This research is important because Long COVID and ME/CFS can look similar. That means people with either illness may benefit from some of the same treatments.

This RECOVER study aimed to better understand how Long COVID affects kids in different ways. Researchers looked at the electronic health records (EHRs) of pediatric patients under the age of 21 who had signs of Long COVID. The study focused on children who were generally healthy and did not have serious long-term health problems before they got sick with COVID-19. Researchers used a special computer method to look for patterns of symptoms in children’s EHRs. This helped them find groups of kids who had similar health problems after having COVID-19, meaning that they had similar experiences with Long COVID. They found that more than half of the children in the study had heart, lung, and breathing problems related to Long COVID. Other common symptoms included muscle and joint pain, mood and thinking problems, stomach issues, headaches, and feeling tired. These findings give researchers a clearer picture of how Long COVID shows up in kids, which can guide future studies.

This RECOVER study looked at whether pregnancy made it more or less likely to get Long COVID. Researchers compared the electronic health records (EHRs) of pregnant women who had COVID-19 during pregnancy to those of non-pregnant women of the same age who also had COVID-19. They found that even though many pregnant women got Long COVID, they were less likely to get it than non-pregnant women their age who had COVID-19. But, certain risk factors increased the chances of Long COVID among pregnant women. These included identifying as Black, being age 35 or older, having COVID-19 earlier in pregnancy, being overweight, and having other health conditions. This study shows that even though many pregnant women have Long COVID, they are less likely to get it than women who are not pregnant.