CHAMPAIGN, Ill. (WAND) - The University of Illinois has announced a COVID-19 vaccine booster requirement for students and employees. 

The school previously listed booster shots as "encouraged", but now students and workers at all three campuses must get a booster as soon as they become eligible, per The News-Gazette. The school cited a recent increase in cases of COVID-19, new guidance from the Centers for Disease Control and Prevention, and "evolving" information about the Omicron variant, which is dominant at the U of I and nationwide. 

U of I President Tim Kileen mentioned there is "significant evidence" that vaccines plus boosters are effective at stopping an infection from becoming serious illness. 

The requirement does not affect those already exempted from a COVID-19 vaccine for medical or religious reasons. Kileen said employees covered by a union contract will see guidance implemented at universities through "applicable collective bargaining processes." 

People who received vaccines outside of Illinois are required to upload their vaccine record to the MyMcKinley portal. 

Those who received two shots of the Pfizer vaccine are eligible for boosters after five months. Booster eligibility is six months after both Moderna shots, and two months after receiving the Johnson & Johnson vaccine.Â