COVID-19 vaccines are unlikely to trigger a rare inflammatory condition associated with coronavirus infection in children, according to an analysis of U.S. government data released Tuesday.
The condition, formally known as multisystem inflammatory syndrome in children, involves fever plus symptoms that affect at least two organs and often include abdominal pain, skin rash or bloodshot eyes. It is a rare complication in children who have had coronavirus infections and very rarely affect adults. The condition often leads to hospitalization, but most patients recover.
First reported in the United Kingdom in early 2020is it sometimes confused with Kawasaki disease, which can cause swelling and heart problems. Since February 2020, more than 6,800 cases have been reported in the United States, according to the Centers for Disease Control and Prevention.
As a part of COVID-19 vaccine safety monitoring, The CDC and the US Food and Drug Administration added the condition to a list of several potential side effects of particular interest. A few cases reported in individuals without detectable evidence of coronavirus infection prompted researchers at the CDC and elsewhere to assume the new analysiswhich was published Tuesday in The Lancet Child & Adolescent Health.
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The possibility that the vaccines may induce the condition in some way is only theoretical, and the analysis found no evidence that it did, said co-author Dr. Buddy Creecha specialist in pediatric infectious disease at Vanderbilt University, who is leading a study of Moderna shots in children.
“We do not know what the exact contribution of the vaccine to these diseases is,” Creech said. “Vaccine alone in the absence of a prior infection does not appear to be a significant trigger.”
The analysis involved surveillance data for the first nine months of COVID-19 vaccination in the United States, from December 2020 to August 2021. During that time, the FDA approved Pfizer’s COVID-19 shots for individuals 16 years of age and older; expanded it in May to young people ages 12 to 15; and approved Moderna and Johnson & Johnson recordings for ages 18 and up.
More than 21 million people aged 12 to 20 received at least one vaccine dose during that time period. Twenty-one of them developed the inflammatory condition afterwards. Everyone had received Pfizer shots, the analysis showed.
Fifteen of the 21 had laboratory evidence of a previous coronavirus infection that could have triggered the condition.
The remaining six had no evidence of a previous infection, but the researchers said they could not conclusively conclude that they had never caught coronavirus or another infection that could have led to the inflammatory condition. Children with coronavirus often have no symptoms and many are never tested.
The results suggest that the inflammatory condition may occur after vaccination in 1 in 1 million children who have had coronavirus and in 1 in 3 million who have no traceable evidence of previous coronavirus infection.
Most children who were infected did not develop the post-infection disease, but it is estimated to occur at a significantly higher rate than both of these post-vaccination figures. In April to June 2020, the frequency was 200 cases per million in unvaccinated, infected people in the United States between the ages of 12 and 20.
Dr. Adam Ratner, a pediatrician-scientist at New York University Langone Health, said the results show that the chances are “super rare” for the shots to elicit an immune response that could lead to the inflammatory condition. In contrast, there is strong evidence that vaccination protects children from getting COVID-19 as well as the condition, Ratner said.