Research Summaries

In this RECOVER study, researchers looked at whether getting COVID-19 a second time increases a child’s or teenager’s risk of developing Long COVID. Researchers compared the electronic health records (EHRs) of more than 400,000 children and teens who had COVID-19 once with the EHRs of about 58,000 children and teens who had COVID-19 twice during the Omicron period. They found that children and teens who had COVID-19 twice were two times more likely to be diagnosed with Long COVID compared to those who only had it once. Children and teens who got COVID-19 twice also experienced other health problems more often, like being very tired, headaches, stomach pain, and heart or kidney problems. This study is important because it shows that children and teens are much more likely to develop Long COVID after getting COVID-19 more than once. These findings show why it is important to continue learning about ways to protect children and teens from getting COVID-19.

In this RECOVER study, researchers looked at whether Paxlovid could help prevent Long COVID. Paxlovid is a medicine commonly used to treat COVID-19 before it makes a person very sick. Researchers looked at the electronic health records (EHRs) of more than 445,000 people who had a high chance of getting very sick from COVID-19. People at higher risk included older adults (aged 50 and up) and people with certain medical conditions. To see if Paxlovid prevented people from developing Long COVID, researchers compared people who took Paxlovid right away once they got COVID-19 to people who did not. To make this a fair comparison, the researchers used a statistical method called a target trial emulation (TTE). A TTE uses EHRs to make two study groups as similar as possible, like they would be in a clinical trial. This makes the comparison fair because positive TTE results are more likely due to taking the treatment (in this study, Paxlovid) and not other differences, like a person’s age or health history. 

Researchers found that Paxlovid did not stop most people who were at high risk of getting very sick from COVID-19 from getting Long COVID. However, people who took Paxlovid were slightly less likely to develop some symptoms linked to Long COVID like fatigue (feeling very tired) and having trouble thinking. Researchers also found that Paxlovid seemed to improve the symptoms of people aged 65 and older a little bit more than it did for younger people. This study is important because it shows that taking Paxlovid is not a way to prevent Long COVID in most people, but it may help reduce symptoms in some higher-risk groups.

In this RECOVER study, researchers created a new computer tool to help doctors identify Long COVID more quickly and accurately. The tool, called a hybrid natural language processing (NLP) pipeline, quickly scans patients’ electronic health records (EHRs) to find descriptions of symptoms and figure out if a patient has them. Researchers tested this tool across 11 US health systems and found it was very accurate at identifying the right Long COVID symptoms. Patient EHRs contain a lot of important information, but it can take a long time to find specific symptoms across thousands of records. Researchers can now look at large amounts of health records from thousands of patients at once using the hybrid NLP pipeline technology. This study is important because it gives researchers a faster, more accurate way to identify Long COVID.

In this RECOVER study, researchers wanted to update a smart computer program, called a machine learning pipeline, to better identify people with Long COVID. In 2021, the first version of the program, called LCM 1, was created to identify people with or likely to have Long COVID. LCM 1 depended on people having a COVID-19 diagnosis date in their electronic health records (EHR). This meant LCM 1 could miss people who may have taken a COVID-19 test at home. LCM 1 also did not look at information about whether people got COVID-19 more than once. To improve the program and create a new version called LCM 2, researchers used more than 5 million EHRs from a large set of data called the National COVID Cohort Collaborative (N3C). They taught the program to look at a person’s health information over many years, not just starting from their first recorded COVID-19 diagnosis. Researchers found that LCM 2 was very accurate. They used it to estimate that about 1 in 10 people in the database who had COVID-19 went on to develop Long COVID. This study is important because it shows that older machine learning models, like LCM 1, can be updated to keep up with the way an illness is tracked and diagnosed over time. This can help other researchers improve their machine learning models to produce more accurate findings.

In this RECOVER study, researchers wanted to find out if getting COVID-19 made young children more likely to get sick later. Some researchers believe that the immune system (the body’s defense system) won’t be able to fight off germs well after someone has had COVID-19. They also thought that children might be more likely to catch the cold-like virus that spread widely in 2022, called respiratory syncytial virus (RSV), or other lung infections after having COVID-19. To learn more, RECOVER researchers looked at the electronic health records (EHRs) of thousands of young children (those less than 5 years old) across 27 US health systems. They compared more than 133,000 young children who had COVID-19 to more than 37,000 young children who had the flu and more than 46,000 young children who had other respiratory infections. Researchers checked for RSV and other respiratory infections for 6 months in each group. They found the opposite of what was believed about the body’s immune system: young children who had COVID-19 were less likely to get RSV or other respiratory infections than young children in the other groups. This study is important because it suggests that getting COVID-19 may not make young children more likely to get RSV or other respiratory illnesses afterward.

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.

In this RECOVER study, researchers wanted to find out whether children (ages 5–12) and teenagers (ages 12–20) who had COVID-19 were more likely to develop mental health conditions than those who never had COVID-19. Researchers studied the electronic health records (EHRs) of more than 1 million children and teenagers to see what mental health conditions they were diagnosed with after getting COVID-19. They found that children who had COVID-19 were more likely to be diagnosed with anxiety, obsessive-compulsive disorder (OCD), attention-deficit/hyperactivity disorder (ADHD), and autism. The researchers also found that teenagers who had COVID-19 had a higher risk of experiencing anxiety, depression, and thoughts of suicide. This study is important because it suggests that getting COVID-19 can increase the chance that young people will experience mental health conditions. Caregivers and doctors must recognize the risk of mental health conditions developing after COVID-19 to help young people get the treatment and support they need.

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 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.