(Reuters) – Two doses Pfizer BioNTech COVID-19 vaccine and Inc (NYSE) are extremely protective against a rare, but sometimes serious condition that can cause organ inflammation in children weeks following COVID-19 infection. This was reported by the U.S. Centers for Disease Control and Prevention on Friday.

Study results showed that the vaccine is 91% effective in preventing Multisystem Inflammatory Disorder in Children (MISC), in children aged 12-18 years old. MIS-C is a condition that causes inflammation in the brain, heart and kidneys in children. It can occur two to six months after a mild, or asymptomatic, infection.

The estimate is based on the assessment of 283 hospitalized patients aged 12–18 years at 24 children’s hospitals in 20 states between July and early December, when the prevalence of the Delta coronavirus variant was high.

According to the study, all 38 MIS–C patients who needed life support were not vaccinated.

These results are part of a larger body that suggests vaccination against COVID-19 may prevent diseases-related complications, such as MIS-C. The Pfizer/BioNTech vaccination did not appear to have prevented this condition.

According to the CDC’s Mortality and Morbidity Weekly Report, (MMWR), the study has limitations.

Children aged 5–11 years are at highest risk for MIS-C but only became eligible for the Pfizer-BioNTech vaccine in late October in the United States. According to the report, they weren’t included in the analysis.