Now that the U.S. Department of Defense is requiring all service members to be vaccinated against the hepatitis B virus (HBV), nearly 8,800 Air Force reservists will have to be immunized by the end of this year, the Air Force Reserve Command reports.

According to the Air Force Reserve Surgeon General’s office, all reservists born before 1990 are in the potential zone for a mandatory three-shot vaccine. The Air Force has been vaccinating new enrollees against hep B since 2002, as well as health care workers and deployed airmen. However, several thousand still remain at risk for HBV.

Service members who are unsure whether they need to be vaccinated can check their immunization status online by visiting imr.afms.mil/imr/MyIMR.aspx.