Controlled studies ease worries of widespread long Covid in kids

Uncertainty about the effect of Covid-19 on children is gradually being replaced by reassuring news.

First, severe complications from Covid-19 are extremely rare in those under age 18. In Connecticut and Massachusetts, the states where we practice medicine, far fewer than 1% of those under age 18 diagnosed Covid have needed to be hospitalized, and that number is declining. Vaccines have proven immensely effective against the virus, in children and teens as well as in adults. This is grounds for relief, and even celebration.

Yet a persistent fear, often focused on the potential for long Covid in kids, looms large for many parents, educational leaders, and even some students themselves. Because of this fear, pandemic-related restrictions like strict mask-wearing requirements persist for children in many places — even where they’ve been relaxed for adults.

But the science tells a different story.

At the beginning of the pandemic, worries about long Covid in kids were not unreasonable. Initial reports suggested that some children with Covid-19 had symptoms like fatigue, cough, or problems sleeping that lasted for more than a few weeks. These wide-ranging symptoms, collectively termed long Covid, were reported as occurring in anywhere from 0% to 80% of children, and they could last for days or weeks.

The early reports, however, often lacked important information, such as whether the kids had co-existing medical conditions or whether they had ever taken a Covid test. Even so, these accounts of the possibility of long-lasting symptoms in children were important. They alerted us to the presence of a potential new health problem at a time when Covid-19 was an entirely new disease and no one really knew what symptoms or long-term effects to look out for.

In scientific parlance, these reports were “hypothesis generating,” meaning they offered an idea of potential problems that would need to be studied more rigorously.

What all of these early studies lacked was a control group. They included only children who reported having had Covid-19. This was a crucial limitation. Until these children could be compared to others who did not report having Covid-19, it was impossible to know whether their symptoms, like fatigue and poor sleep, were due to the virus or to the general stresses that children have been enduring during the pandemic — or even to chance.

Over the last two years, experts’ understanding of long Covid in children has deepened. Several peer-reviewed studies now include control groups consisting of children who did not have Covid-19 but who have lived through the same pandemic conditions — loneliness, interrupted schooling, anxiety, tensions at home, the loss of loved ones, and the like.

These studies indicate that long Covid in children is rare and, when it does occur, is short-lived. In one study, 97% of children ages 5 to 11 with Covid-19 recovered completely within four weeks. In the small group that had bothersome symptoms after four weeks (usually loss of smell or fatigue), most had fully recovered by eight weeks.

In two other studies that included scientific controls, the rates of long Covid symptoms were nearly the same in children who had tested positive for Covid-19 compared to those who didn’t. In other words, other factors were to blame in many or most of these cases.

Indeed, children who had not had Covid-19 reported higher rates of many symptoms, including difficulty concentrating and muscle pains — nearly every long Covid symptom except the loss of smell and taste. Similar findings have also been reported in controlled studies in adults.

To be sure, debilitating Covid-19 symptoms persist for weeks in a small number of children, likely due to lingering effects of infection and the body’s immune response to it. But the studies that include control groups tell us that the odds of this occurring in a child with Covid-19 is low, lower even than the odds of getting seriously injured while playing sports.

Controlled studies like the CLoCk study in England, published in Lancet Child and Adolescent Health on Feb. 7, also offer crucial information about the mental health toll the Covid-19 pandemic has taken on children, regardless of whether they had personally been infected with the virus that causes Covid-19. An alarming 40% of teens surveyed — those who had Covid-19 and those who did not have it — reported feeling worried, sad, or unhappy. These mental health symptoms are real, but the data indicate that, more often than not, they are not a consequence of direct Covid-19 infection. Among those who did have Covid-19, poor mental health before getting Covid-19 was an important risk factor for having multiple long Covid symptoms after three months, highlighting the importance of accounting for mental health conditions in studies of pediatric long Covid.

Framed this way, restrictions on children should not be maintained in the name of preventing long Covid.

Fear has had a strong hold on Americans for more than two years, and it is a hard thing to let go of. But we owe it to children to follow the science: Children are more likely to suffer from pandemic-associated symptoms than from infection-associated symptoms. School policies should reflect this reality.

Families and school staff need to be given factual, reassuring messaging about the actual risks of Covid-19 to children, put away the masks in most school settings — at least for now — and restore a sense of normalcy to their day-to-day lives.

Shelli Farhadian is an infectious disease physician and an assistant professor of medicine and of neurology at the Yale School of Medicine who is studying how Covid-19 affects the brain. Shira Doron is an infectious disease physician and hospital epidemiologist at Tufts Medical Center in Boston and an associate professor of medicine at Tufts University School of Medicine.