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 looks at how often people get COVID-19 more than once and if they develop Long COVID afterward. The study also looks at whether a repeat COVID-19 infection, or reinfection, is worse than the first one. RECOVER researchers identified a reinfection when a person had a positive COVID-19 test at least 60 days after their first infection. They studied the health records of over 3 million patients in different ways to understand COVID-19 reinfections. By studying a large number of patients, the researchers were able to learn key details about COVID-19 reinfections. They found that about 6.9% of people got COVID-19 more than once. Most reinfections happened when the Omicron variant was spreading. Researchers found that Long COVID was more common in people who had COVID-19 for the first time compared to those who were reinfected. This finding suggests that protecting yourself from getting COVID-19 is the best way to prevent Long COVID. People who had a moderate or severe case of COVID-19 the first time were also more likely to get very sick again when they were reinfected. These people were often older and at higher risk of death.
Some people develop new conditions or symptoms after a COVID infection, called Long COVID. This can lead to ongoing health problems. Researchers still don’t fully understand why some people get Long COVID while others do not. In this RECOVER study, researchers wanted to learn what increases someone’s risk of developing Long COVID after getting COVID. Researchers studied the electronic health records of 2.1 million people from New York and Florida who either had, or had not had, a COVID infection between March 2020 and November 2021. Using this data, they created a new computational model (a computer program that imitates how something works in real life) to help identify the things that Long COVID patients had in common. The researchers looked at whether these shared factors increased their risk of developing Long COVID. The model found that the people who were more likely to develop Long COVID if they had a severe first COVID infection, were underweight, or had other health problems, like cancer or liver disease. The results also show that computational models can help identify people who have a higher chance of developing different symptoms and types of Long COVID. This information is important because it can be used to help researchers find new ways to prevent, diagnose, and treat Long COVID.
Little is known about Long COVID in pregnant women. This study looked at whether getting COVID while pregnant might increase the chances of getting Long COVID. Researchers from the RECOVER Patient-Centered Clinical Research Network (PCORnet) checked health records from 19 health systems across the US. They studied women ages 18–49 years old who had a test showing that they had a COVID infection between March 2020 and February 2022, and looked at 83,915 women who were not pregnant and 5,397 who were. Women who got COVID while pregnant were less likely to get Long COVID than those who weren’t pregnant. Pregnant women with COVID were more likely to develop certain conditions related to Long COVID, like an abnormal heartbeat. But they had a lower risk of getting other conditions, like malaise (feeling unwell). Overall, pregnant women with COVID had a lower chance of getting Long COVID in the 30 to 180 days after they first got sick.
The virus that causes COVID-19 can change over time, creating new virus types called variants. This study explored if problems related to Long COVID were different in people who were infected with different variants of COVID. Researchers looked at medical records from 2 databases in New York and Florida. They compared people who had the original type of COVID with those who had a variant called Delta, which was one of the main variants in 2021. The researchers found that some Long COVID conditions were more common in the people who had Delta. For example, some people infected with Delta developed clots in the blood vessels in their lungs. People who had Delta were also more likely to have stomach symptoms than people who were infected with the original type of COVID. Based on these findings, the researchers concluded that Long COVID symptoms can be different depending on which variant of COVID someone had.
Doctors keep patient information in computer files called electronic health records (EHRs). RECOVER researchers can use these records to learn more about Long COVID, which is when someone feels sick for a long time after having COVID-19. But studying these records is not easy. It can be hard to get certain information from EHRs, when things that might explain why some people get Long COVID happen at different times. It can also be hard to put information from many hospitals together in one place and can cost a lot of money. In this study, RECOVER researchers made a new tool called ODACoR, which stands for “one-shot distributed algorithms for competing risks model.” This tool was used to look at the EHRs of 6.5 million kids and teens from 8 children’s hospitals. Researchers found that ODACoR was able to find information about things that could make children and teens more likely to get Long COVID. ODACoR could also combine information from different hospitals, which did not always work with old ways of studying health information. This tool gave the same results as if all the hospitals had shared all their information in one place, which is hard to do. This study is important because it can help doctors study other kinds of health problems using information from many hospitals.
This RECOVER study looks at how well and how long a COVID-19 vaccine, BNT162b2, works in children and teens. Researchers studied this before and during the wave of a new type of COVID, called Omicron. Researchers looked at the electronic health records from a group of children’s health systems across the country, known as PEDSnet. They checked 3 groups: teens ages 12–20 during the earlier Delta wave; and both children ages 5–11 and teens ages 12-20 during the Omicron wave. Researchers looked at data from more than 77,000 teenagers during Delta and over 167,000 kids and teens during Omicron. Some of these kids were vaccinated, and some were not. Researchers compared those who got the first dose of the BNT162b2 vaccine to those who didn't get any COVID vaccine. During Delta, researchers found that the vaccine stopped almost all the teenagers (98%) from getting sick. In the Omicron wave, the vaccine helped stop 74% of the kids and 86% of the teenagers from getting COVID. It also helped keep kids from getting really sick and needing to go to the hospital. Children and teens who got vaccinated were also less likely to have heart problems during Omicron. But they found that the vaccines didn’t work as well 4 months after the first dose. This information helps doctors better understand how to keep kids healthy when COVID is going around.
This RECOVER study looked at why some people may have long lasting symptoms or new health problems after getting COVID-19. Researchers looked at the electronic health records of 3.7 million adults and children who were tested for COVID between March 2020 and May 2021. They compared the records of people who tested positive for COVID with people who did not.
The study found that both adults and children who were hospitalized with COVID were more likely to have at least 1 symptom in the months after getting COVID, like shortness of breath. They also found that adults who were hospitalized with COVID were more likely to have 3 or more symptoms, feel very tired, or develop a new health condition. Some of the conditions were diabetes, blood disorders, or diseases related to breathing. Even adults with COVID who were not hospitalized had a higher chance of certain symptoms or health issues compared to those who did not have COVID. This study is important because it shows that COVID can impact people’s health for a long time, even after their first infection is gone. These findings can help doctors and scientists better understand how to treat and care for people recovering from COVID.
Research shows that the COVID-19 vaccine lowers the chance of children getting sick from COVID. But it is not clear whether the COVID vaccine protects against Long COVID. RECOVER researchers did a study to look at how well vaccines work in protecting children, ages 5–17, against Long COVID. They studied data from a group of more than 1 million children. The vaccine was 42% effective in lowering the chance of getting Long COVID in kids ages 5–11 and 50% effective for kids ages 12–17. The vaccine works best against Long COVID within the first 6 months of getting it. After 6 months, it does not work as well, so getting the vaccine every year is important to prevent Long COVID. These results show that the COVID vaccine can help children 5 years and older to keep from getting very sick. While this study helps scientists understand how vaccines can protect against COVID, they still need to do more research to understand how they protect against Long COVID.
RECOVER researchers studied how multisystem inflammatory syndrome (MIS-C) looks different in a large group of children. The researchers looked at electronic health record (EHR) data from 8 children’s hospitals from March 2020 to September 2022. They studied 1,139 children who were patients hospitalized for MIS-C. The researchers divided the patients into 3 groups and used age, sex, location, symptoms, conditions, test results, and medications to look for patterns in these groups. Researchers then looked at how the groups were similar and how they changed over time. The study showed that MIS-C has a range of severity, from mild to medium and severe. This means that MIS-C symptoms can be different for each child. The researchers also found that there are fewer severe MIS-C cases now than there used to be. The study might not have included some children if they had symptoms like MIS-C but had a different illness, had Kawasaki disease when they were in the hospital (because of how similar the symptoms can be to MIS-C), or had mild MIS-C symptoms that did not bother them that much and may not have been written in their EHR. This study can help doctors better understand and treat MIS-C.
