Research Summaries

Researchers wanted to know why some children get sicker than others when they get COVID-19. Different versions (variants) of SARS-CoV-2, the virus that causes COVID-19, can affect children differently. A child’s age, sex, race, or ethnicity (demographic factors) may also play a role in determining which COVID symptoms they experience—and how burdensome (severe) those symptoms become.

Researchers reviewed electronic health record (EHR) data from a large group of children (ages 0–25) who visited Children’s Hospital Los Angeles between 2020 and 2024 and tested positive for SARS-CoV-2. Next, researchers analyzed biosamples to identify which viral variant was responsible for causing a child's COVID-19. Researchers then compared COVID-19 severity between different viral variants and demographic factors.

Researchers found that COVID-19 caused by the Omicron variant was more likely to be associated with moderate or severe COVID-19 in children compared to COVID-19 caused by earlier variants, like Delta or Epsilon. This finding contrasts with studies in adults that generally found that Omicron infections were milder. The authors also noted that Long COVID cases did not appear to cluster around specific variant periods, suggesting that children’s risk of developing Long COVID may not be tied to a particular variant in the same way it may be in adults.

In terms of demographic factors, researchers found that children who were male had an increased likelihood of experiencing moderate or severe COVID-19 compared with females. Younger children (0–5 years) showed an increased likelihood of experiencing moderate or severe COVID-19 compared to older children. Researchers also found that COVID-19 severity can differ across racial and ethnic groups. For example, Hispanic/Latino and White children included in the study were less likely to develop severe COVID-19 as their age increased, while the data showed Asian children showed a slight increase in severe illness at older ages.

These findings suggest that age, race and ethnicity, and viral variants may interact in complex ways to influence how sick a child becomes with COVID-19. Understanding how viral variants interact with children’s demographic characteristics could inform how health providers care for children who may be at higher risk of experiencing severe COVID-19 or Long COVID.

In this RECOVER study, researchers wanted to learn how Long COVID affects the everyday functioning of children, teenagers, and young adults. Researchers examined the electronic health records (EHRs) of 686 children and young adults under 21 years old, including 651 who got COVID-19 and received care in 21 hospitals across the U.S. They compared young people who had Long COVID to those who had COVID-19 but did not have Long COVID. They found that young people with Long COVID were more likely to have trouble in school, need extra school support, and develop new or worsening behavioral or mental health issues like anxiety and depression. This study is important because it highlights that doctors should ask about school, daily activities, and emotional well-being when caring for young people who’ve had COVID-19. Long COVID can affect these parts of everyday life and require extra support.

RECOVER researchers looked at whether taking selective serotonin reuptake inhibitors (SSRIs) and serotonin–norepinephrine reuptake inhibitors (SNRIs) around the time of having COVID-19 was linked to Long COVID in children, teenagers, and young adults. SSRIs and SNRIs are medicines used to manage mood and mental health symptoms. Researchers reviewed the electronic health records (EHRs) of more than 110,000 young people (ages 5 to 20) who had neuropsychiatric conditions and COVID-19. Neuropsychiatric conditions are disorders that affect how the brain works and how a person thinks, feels, or acts. Researchers compared young people who took SSRIs or SNRIs to those who did not. The study found that taking SSRIs or SNRIs was not linked to a higher or lower chance of receiving a Long COVID diagnosis. However, young people taking these medicines were less likely to experience fever, chills, or hair loss after having COVID-19. Young people taking these medicines were more likely to experience extreme tiredness (fatigue), memory problems, and postural orthostatic tachycardia syndrome (POTS, which is a condition that can cause a fast heart rate when standing up). These findings are important because they suggest that children, teens, and young adults taking SSRIs or SNRIs may have different long-term symptoms after getting COVID-19, which doctors should monitor.

In this RECOVER study, researchers looked at whether children who received steroids soon after getting COVID-19 were less likely to develop Long COVID. Steroids are medicines that help with inflammation (swelling and irritation) in the body. Researchers reviewed the electronic health records (EHRs) of more than 850,000 children under 19 years old who had a positive COVID-19 test, a COVID-19 diagnosis, or received antiviral medicines for COVID-19 between March 2020 and April 2024. Researchers then compared children who received steroids within 12 days of getting COVID-19 to those who did not. They also looked at children who were hospitalized and children who were treated at home. Researchers found that steroid use was not linked to a lower risk of developing Long COVID. However, children who were not hospitalized with COVID-19 and took steroids had a lower risk of experiencing stomach problems associated with Long COVID. This study is important because it shows that early steroid use was not linked to a lower risk of Long COVID in children. More research is needed to understand which treatments may help prevent long-term symptoms from developing in children who get COVID-19.

In this RECOVER study, researchers looked at the relationship between a young person’s weight and their health after getting COVID-19. Researchers reviewed the electronic health records (EHRs) of over 139,000 children and young adults, ages 5–20 years, across the US. They grouped participants based on their body mass index (BMI). BMI is a number that helps show whether someone is at a healthy weight, is overweight, has obesity, or has severe obesity based on their height and weight. The researchers checked if any new health problems were added to participants’ EHRs between 1 and 6 months after getting COVID-19. The study found that children and young adults with severe obesity were much more likely to develop health problems after getting COVID-19. These included problems related to the heart, like high blood pressure, and stomach problems, like diarrhea and heartburn. The researchers also checked whether participants had mental health issues after getting COVID-19. Those results were less clear and may have been due to other factors. This study is important because it shows that doctors should be thinking about the weight of children and young adults affected by COVID-19. If a child is overweight or has obesity and gets COVID-19, doctors should monitor their heart and stomach health to make sure they receive the care they need. 

This RECOVER study looked at whether COVID-19 was linked to a higher risk for dyslipidemia (unusual levels of fats or cholesterol in the blood) or a high body mass index (BMI) in children and young adults. BMI is a number that helps show if someone's weight is in the healthy range for their height. A higher BMI can be a sign that a person may be overweight or have obesity. Researchers looked at the electronic health records (EHRs) of over one million children and young adults, from birth to age 21, across 25 different children’s hospitals in the US. Researchers followed the health of children and young adults for up to 6 months after they got COVID-19 for the first time and compared them to a group of children and young adults who did not get COVID-19. Researchers found that children and young adults who got COVID-19 were about 24% more likely to develop dyslipidemia and 15% more likely to develop a high or unhealthy BMI than those who never had COVID-19. These findings are important because they show that COVID-19 may be linked to a higher risk of health problems related to blood fats and weight. These findings also highlight the need for closer follow-up of children and young adults during their recovery from COVID-19.  

This RECOVER study tested a new way to identify Long COVID in children. Researchers created a special computer-based tool, called a computable phenotype (CP), that scans electronic health records (EHRs) for specific codes and symptoms linked to Long COVID. To test the CP, researchers scanned records for nearly 340,000 children who had COVID-19. Doctors then checked a smaller group of 651 children’s records to see how well it worked. The study showed that the CP was able to successfully find that a child had Long COVID. But it sometimes marked symptoms that fit in with health problems someone had before getting COVID-19 (pre-existing conditions), so it wasn’t clear if those symptoms were due to COVID-19. When the researchers updated the CP to pay closer attention to pre-existing conditions, it became more accurate at identifying Long COVID from EHRs. This study is important because it provides a faster and more consistent way for researchers to identify Long COVID in large groups of children. This tool can help doctors give better care to children with Long COVID.

In this RECOVER study, researchers wanted to find out if natural language processing (NLP) could be used to identify Long COVID symptoms in children. NLP is a tool that can help find details in electronic health records (EHRs) beyond what is usually looked at in EHRs, such as diagnosis or billing codes (known as standard EHR data). Researchers used an NLP tool to look for 25 signs of Long COVID in children: 21 symptoms (like pain or extreme tiredness) and 4 types of daily life challenges (such as trouble with school). They compared children who had been diagnosed with Long COVID to those who had COVID-19 but did not develop Long COVID. The NLP tool analyzed more than 48,000 doctors’ notes within the EHRs of more than 10,000 children across 12 hospitals. Researchers found that the NLP tool identified almost all 25 symptoms much more often in the children who had Long COVID. The NLP tool also often identified patients’ symptoms that were not recognized when researchers only looked at standard EHR data. The study shows that using NLP to read EHR notes can help researchers better understand the symptoms and daily challenges that children with Long COVID experience when compared to looking only at codes and medication lists. This supports the idea that NLP should be used when doing scientific studies that need to identify children with Long COVID.

In this RECOVER study, researchers wanted to understand the connection between Long COVID and chronic kidney disease (CKD) in adults who had COVID-19. CKD is long-term, permanent damage to the kidneys. Researchers looked at the electronic health records (EHRs) of more than 2 million adults across 59 health systems in the US to see if people with CKD were more likely to develop Long COVID. The study found that, compared to people without CKD, those who had even mild cases of CKD were more likely to get Long COVID after COVID-19. Researchers also found that, compared to adults who did not get Long COVID, those who developed Long COVID and had healthy kidneys before getting COVID-19 were more likely to develop new CKD or have worsened kidney function within a year. These findings show how Long COVID and kidney disease can affect each other and highlight how important it is for doctors to monitor people’s kidney health after they get COVID-19.