Children's hospitals nationwide are keeping a close eye on cases of multisystem inflammatory syndrome in children, or MIS-C, in the wake of the omicron wave, CNN reported Feb. 22.
Six things to know:
1. Throughout the pandemic, MIS-C cases have consistently appeared about two to six weeks after a national COVID-19 surge, according to Roberta DeBiasi, MD, chief of the infectious disease division at Children's National Hospital in Washington, D.C.
2. While the pattern is consistent, Children's National has seen fewer cases after each wave. After the first surge, the hospital treated 100 children with MIS-C. After delta, it saw about 60, according to Dr. DeBiasi. It's unclear why case volumes are dropping, though Dr. DeBiasi said she suspects increasing pediatric vaccination rates may be a contributing factor.
3. Now that the omicron surge is waning, children's hospitals are closely monitoring MIS-C cases. Many hospitals told CNN they are not seeing a major spike in cases, despite the large volume of children who contracted COVID-19 during the latest surge.
"The MIS-C children, we thought we may see an uptick with omicron, but we haven't. It's very similar for us with the delta surge," Pei-Ni Jone, MD, a cardiology specialist at Aurora-based Children's Hospital of Colorado, told CNN. "It's really unknown what's driving the MIS-C cases."
4. Children's Hospital of Los Angeles and Lurie Children's Hospital of Chicago are also seeing lower numbers than expected. However, Seattle Children's Hospital is reporting a spike in cases.
"Approximately 15 percent of the total MIS-C cases we've seen since March 2020 have occurred since mid-December 2021, when omicron emerged as the main variant. These numbers suggest that MIS-C is increasing with omicron," Michael Portman, MD, the hospital's director of research in the division of cardiology, told CNN.
5. As of Jan. 31, the most recent data available, there have been 6,851 MIS-C cases reported nationwide, along with 59 deaths, according to the CDC. Overall, more than 12.5 million kids have contracted COVID-19 during the pandemic, data from the American Academy of Pediatrics shows.
6. MIS-C cases may be even rarer among kids 12 and up who've received a COVID-19 vaccine, according to research published Feb. 22 in The Lancet Child & Adolescent Health. Among more than 21 million kids who received at least one dose of Pfizer's vaccine between Dec. 14, 2020, and Aug. 31, 2021, researchers identified just 21 with MIS-C after vaccination.