Until recently, the headlines about Covid-19 have largely been about the disease in adults, especially the elderly and those people with underlying health conditions. As a pediatrician, I'm used to seeing viruses like influenza and Respiratory Syncytial Virus (RSV) wreak absolute havoc in children. So, it has been an unexpected, albeit very welcome, "surprise" that Covid-19 seems to be having very little effect on children. However, over the past few weeks, it seems that doctors around the globe are noting cases of children who are being diagnosed with severe inflammation throughout their body-something the Center for Disease Control is now calling "Multi-system Inflammatory Syndrome in Children" or MIS-C for short. The headlines about this new development in kids are frightening, so let's talk about what MIS-C is and how worried parents need to be (keep reading for the good news here).

Doctors really like to follow trends or clusters of illnesses, so when doctors in New York City started to see an increase in cases of children with overwhelming inflammation presenting to the hospital, it certainly was noteworthy. Symptoms of children presenting with MIS-C have been varied but include high unrelenting fever, abdominal pain, diarrhea, rash, red eyes, and neck pain. These children are showing massive amounts of inflammation in their blood vessels causing problems in organs such as the heart, kidney, gastrointestinal tract, and brain. Some of the children who have been diagnosed with MIS-C have been found to have positive antibody tests to Covid-19 without a prior diagnosis of a Covid-19 infection. This would signal that MIS-C would have occurred weeks after a Covid-19 infection (again most likely an asymptomatic infection). It is important to note, however, that there have also been children diagnosed with MIS-C who have had all negative testing to Covid-19.

The bottom line right now is that we are not sure what is causing MIS-C.

MIS-C is closely resembling two other rare illnesses that we see in children…one called Kawasaki disease and one called Toxic Shock Syndrome. The cause of Kawasaki disease is  not truly known, but doctors have long suspected that it is likely a post-viral illness where the body's immune system starts to almost attack itself, leading to inflammation of blood vessels in different areas of the body, including the heart. Children with Kawasaki disease present with high fever for more than 5 days, rash, redness to the eyes, changes to their lips or tongue as well as swelling of the extremities and swollen lymph nodes. Kawasaki disease can be treated, and the majority of children recover from this illness without long-term effects (although in some cases, long-term damage to the coronary arteries can occur). Toxic shock syndrome, on the other hand, is caused by bacteria (either Staph or Strep) and can be life-threatening very quickly as it causes extremely low blood pressure, also known as shock.

When the initial cases of MIS-C were seen, children seemed to be presented with some of the physical signs of Kawasaki disease but with the low blood pressure seen in Toxic Shock Syndrome. As more information is collected, it also seems that children with MIS-C are older with the most common ages being 5 and up.

Kawasaki disease, on the other hand, is more commonly seen under the age of 5 (although both of these illnesses can be seen in anyone under the age of 18). As with a lot of things in medicine right now, we are trying to learn as quickly as we can about the disease process of MIS-C, and work is ongoing to determine whether there is a direct link to Covid-19, whether some children were more likely to get MIS-C than others, and whether there is any way to prevent MIS-C from happening.

So, you might be wondering: what about the good news I mentioned above? Well, while the headlines are scary about MIS-C, the most important thing I want parents to take away from this is that MIS-C is still EXTREMELY RARE. While data collection is continuing daily, as of this writing, 23 states are reporting cases of MIS-C, there are around 250 cases across the US (with close to 100 of those cases being in New York alone), but at the moment, there have been less than 5 deaths nationwide. Just to be clear, while any child dying is absolutely tragic, do keep in mind for reference that influenza has already killed 176 children so far this year.

When it comes to MIS-C, doctors and parents alike need to be aware of this new illness and be on the lookout for concerning symptoms. But once again, there is no need to panic as this illness, while scary given its symptoms and complications, remains exceedingly rare. Doctors and scientists are feverishly working to try and learn as much as possible about MIS-C, and its causes, relationship to Covid-19, and, of course, treatment and a cure.

In the meantime, I encourage parents that may be worried about MIS-C to speak with their pediatrician, and if you are worried about your child being ill with any kind of symptoms, please do not be afraid to bring them to the doctor. Pediatricians are available and equipped to see children both healthy and sick during these uncertain times of Covid-19.

Mindy L. Calandro, MD, FAAP