When the COVID-19 pandemic began in early 2020, researchers reported an increase in cases of Kawasaki disease, an illness that causes widespread inflammation in children under age 5.

Although the cause of Kawasaki disease isn’t clear, research suggests that both genetic and environmental factors play a role. It may affect genetically predisposed children following exposure to a viral infection — for instance, the novel coronavirus, SARS-CoV-2.

This article reviews how COVID-19 affects children with Kawasaki disease, along with typical diagnosis and treatment methods.

Kawasaki disease was first described in the 1960s by Dr. Tomisaku Kawasaki, a Japanese pediatrician. Although it can occur anywhere in the world, it occurs at a higher rate in Japan.

The Centers for Disease Control and Prevention (CDC) reported that in the continental United States, Kawasaki disease led to approximately 3,935 hospitalizations of children under age 5 in 2016. It is more likely to affect boys.

Kawasaki disease causes inflammation of the blood vessels. If left untreated, it can damage the coronary arteries and significantly increase the risk of aneurysms and heart attacks.

Common signs and symptoms of Kawasaki disease include:

If a child in your care has a high fever along with some or all of the symptoms listed above, seek medical assistance.

Researchers documented a sharp increase in cases of an illness that resembled Kawasaki disease during the early months of the COVID-19 pandemic.

For example, a 2020 study from the United Kingdom described eight children who were hospitalized for symptoms that resembled Kawasaki disease or similar conditions during a 10-day period in mid-April 2020. Researchers described this as an “unprecedented” amount.

Another 2020 study from France compared monthly instances of Kawasaki disease from December 2005 to mid-May 2020. Researchers reported a 497 percent increase in hospitalizations in April 2020 compared with previous months, which corresponded with a peak in the COVID-19 pandemic. In addition, 80 percent of those hospitalized were also diagnosed with a coronavirus infection.

And another 2020 study from Italy also described an increase in cases of a severe form of Kawasaki disease during the early months of the COVID-19 pandemic.

However, other studies reported stable or decreased levels of hospital admission for Kawasaki disease in the COVID-19 era.

For instance, the authors of a large-scale 2021 study from Japan found that pediatric hospitalizations for Kawasaki disease remained stable during Japan’s state of emergency from April to May 2020. Meanwhile, rates of illnesses believed to trigger Kawasaki disease, including common respiratory and gastrointestinal tract infections, decreased.

Researchers concluded that since Kawasaki disease was still present during this period, it might be associated with airborne diseases, such as COVID-19 and influenza, as opposed to illnesses that are transmitted via droplets or physical contact.

A 2021 study from the United States reported an overall decrease in instances of Kawasaki disease over the course of 2020, although cases peaked in May.

Study authors pointed out that during this period, Kawasaki disease tended to affect older children and cause more severe symptoms. They suggested the potential for misdiagnoses of multisystem inflammatory syndrome in children (MIS-C), an illness described in the next section.

Finally, an Iran-based 2021 study found that hospitalizations for Kawasaki disease remained stable during the COVID-19 pandemic. However, 68 percent of those admitted also had COVID-19.

There are major discrepancies in these studies. While COVID-19 appears to increase the risk of inflammatory symptoms in young people, it’s not always clear whether Kawasaki disease is the cause.

As most of the study authors cited above indicated, there’s a need for additional research to further understand the relationship between Kawasaki disease and COVID-19.

Multisystem inflammatory syndrome in children (MIS-C) can cause symptoms that resemble Kawasaki disease, including all of those listed in the above section. And like Kawasaki disease, MIS-C can cause heart complications.

However, according to the American Academy of Pediatrics, MIS-C may also cause additional symptoms, including:

Another difference is that Kawasaki disease tends to affect young children, while MIS-C appears to affect both children and adolescents.

According to the CDC’s diagnostic criteria for MIS-C, doctors must also look for a positive COVID-19 test within the past month. A positive COVID-19 test isn’t required to diagnose Kawasaki disease.

There’s no definitive test for Kawasaki disease. Instead, your doctor will try to rule out illnesses that cause similar symptoms while also determining whether a secondary infection, such as COVID-19, is present.

You might be asked to describe your child’s symptoms and medical history. Your child might also undergo routine tests, such as:

According to the CDC, a doctor diagnoses Kawasaki disease when a fever lasts for more than 5 consecutive days. In addition, doctors check for 4 out of the 5 following symptoms:

  • rash
  • swollen lymph nodes in the neck
  • red eyes
  • changes in the appearance of the lips, mouth, and tongue
  • changes in the hands and feet, such as swelling or peeling skin

It’s possible to receive a Kawasaki disease diagnosis without having four of the symptoms listed above. If your child has a fever and coronary artery abnormalities, it could be a sign of atypical Kawasaki disease.

Kawasaki disease should be treated as soon as possible. Your pediatrician will take steps to lower your child’s fever, reduce inflammation, and prevent complications such as heart problems.

Treatments typically include:

  • Aspirin. In cases of Kawasaki disease, a high dose of aspirin can bring down the fever and reduce inflammation. Aspirin may also target general discomfort. However, do not treat a child’s fever with aspirin unless aspirin is specifically prescribed by your doctor.
  • Intravenous (IV) immunoglobulin. Immunoglobulin is an antibody that can decrease blood vessel inflammation. It can help reduce the risk of cardiovascular complications.
  • Corticosteroids. Steroids can reduce the risk of heart complications caused by Kawasaki disease. They can also relieve symptoms including rashes and fever.

Aspirin warning

Aspirin is generally not recommended for children because it’s associated with serious complications, such as Reye’s syndrome.

Never give a child aspirin to treat a fever at home without a doctor’s care or monitoring.

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How is Kawasaki disease treated in children with COVID-19?

When a coronavirus infection is present, the treatment for Kawasaki disease does not change. Aspirin, intravenous immunoglobulin, and corticosteroids are the main doctor-prescribed treatments.

According to a 2020 review, additional treatments can include:

There’s little research available right now regarding the vaccination of children with Kawasaki disease against COVID-19.

COVID-19 vaccines have yet to be approved for children under the age of 5, the population most likely to be affected by Kawasaki disease.

However, according to the nonprofit Kawasaki Disease Foundation, there’s no reason to believe that COVID-19 vaccines pose additional risks to children who have previously had Kawasaki disease.

With treatment, Kawasaki disease typically lasts about 2 weeks.

Once your child’s fever has broken, treatment may continue for longer to prevent cardiovascular side effects. During this time, your pediatrician may monitor your child to rule out heart complications.

Among children who have received early diagnosis and treatment, most make a full recovery with no long-term health effects. A small minority of children will develop long-term heart problems, which require treatment from a pediatric heart specialist.

Deaths associated with Kawasaki disease and COVID-19 are extremely rare.

Kawasaki disease is an inflammation-based illness that causes fever in children under the age of 5. Researchers don’t know exactly what causes it. It appears to develop in genetically susceptible children after exposure to an infection, such as the coronavirus SARS-CoV-2.

Some countries reported an increase in instances of Kawasaki disease during the first months of the COVID-19 pandemic, while others reported that cases either remained stable or decreased. Research into the link between Kawasaki disease and COVID-19 is ongoing.

Kawasaki disease closely resembles MIS-C, another inflammation-based illness that has occurred at an increased rate during the pandemic. Symptoms of Kawasaki disease and MIS-C often overlap, making it difficult to distinguish between the two.

If your child has a persistent high fever, it’s important to seek medical care quickly to determine the cause and get treatment.