What you should know about a new childhood disease linked to Covid-19

  • Multisystem inflammatory syndrome is a new disease that affects children with Covid-19
  • Fever, vomiting and diarrhoea are some of the common symptoms – separate from the coronavirus
  • Almost half of sufferers have abnormal heart ultrasounds

While children get off quite lightly from Covid-19, with a low mortality rate, doctors and researchers have noticed that the virus might have sparked a rare new disease.

A hyperinflammatory condition linked to the coronavirus has been identified and is being studied by researchers. It is called multisystem inflammatory syndrome in children (MIS-C). The disease is quite dangerous and could even be lethal.

"The definition of [MIS-C] across the organisations is based on six principle elements: paediatric age, persistence of fever, presence of laboratory markers of inflammation, manifestation of signs or symptoms of organ dysfunction, lacking an alternative diagnosis, and a temporal relation to Covid-19 infection or exposure," write the authors of a review of studies dealing with the mysterious disease.

READ | A guide to managing children's diabetes during Covid-19 

Different from Kawasaki's and toxic shock

The new disease was first reported in April among UK patients, and other countries have since then also observed MIS-C in young Covid-19 patients. It's quite difficult to differentiate it from Kawasaki's Disease (KD) and toxic shock syndrome (TSS) due to similar symptoms, but it remains a separate disease.

"While MIS-C has overlapping features with KD and TSS, the inflammatory storm observed in MIS-C is much more intense.

"Another important difference to highlight between KD and MIS-C is that approximately 5% of children with Kawasaki's disease presented with cardiovascular collapse. Conversely, 60.2% of children with MIS-C presented with shock."  

What to look out for

The researchers collated 39 observational studies involving 662 patients to better understand this new disease, publishing their findings in EClinicalMedicine. The cases – mostly from the US – had an average age of about nine and stayed around eight days in hospital.

Those with KD are normally younger, under the age of five.

About 71% of them were admitted to ICU, while only 1.7% died. This is higher than the child mortality rate for Covid-19.

The most popular symptoms were fever, which was present in all cases, while 73.7% suffered from abdominal pain or diarrhoea, and 68.3% from vomiting. Conjunctivitis and a rash were also frequently observed.

READ MORE | Covid-19 virus and antibodies can coexist in children, new study finds 

Abnormal heart scans

Less than a fifth was placed on a ventilator, but the biggest finding came from their echocardiographs, an ultrasound of the heart.

Just more than half of the scans were abnormal, most of them showing a depressed ejection fraction. This means that the percentage of blood being pumped out of a filled heart ventricle is below 50%.

"Although children were critically ill and had extraordinary inflammation, most responded to prompt administration of anti-inflammatory agents, namely intravenous immunoglobulin and corticosteroids.

"Among the more concerning findings was that children could still develop MIS-C despite an asymptomatic course of coronavirus 2019 disease. The literature reports that MIS-C typically manifests three to four weeks after SARS-CoV-2 infection."

Other factors

Other worries are that just more than half of the patients had no other underlying health conditions – although half were obese – and the disease is disproportionately affecting African-descendant communities. 

While the study offers valuable insight into the disease for clinicians, they caution that the studies have a low level of evidence and are mainly descriptive as the disease is still rare.

"Accordingly, children undergoing evaluation for MIS-C should have a baseline echocardiogram, electrocardiogram, and repeat imaging to follow cardiac function and artery change."

The long-term effects of Covid-19 – and MIS-C – are still unknown, and only time will tell what impact it could have on the health of younger generations.

READ | Children can carry Covid-19 virus in their respiratory tracts for weeks, study finds

Image credit: Getty Images

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