Vaccine Needed for Second Doses will Outnumber First Doses in the Coming Weeks

IDPH Works with Local Health Departments to Balance First and Second Doses

SPRINGFIELD – Beginning the week of February 15, local health departments and other COVID-19 vaccine providers will begin to receive a larger share of second doses to accommodate a greater number of second doses coming due.  With federal shipments of the vaccine to Illinois remaining limited, this will mean providers will receive a smaller share of first doses.  Based on federal projections of vaccine shipments, the Illinois Department of Public Health (IDPH) anticipates these allocations will hold steady for the next several weeks, before allocations of first doses can once again increase in March.

IDPH has communicated extensively with local health departments and other providers to prepare for this shift in allocations and ensure those due for second doses can receive them in a timely manner.  This has included webinars, individual planning calls, and a rapid electronic notification to all vaccine providers.

Both the Moderna and Pfizer vaccines require a second dose to be up to 95% effective.  Second doses need to be administered four weeks after the first dose for those who receive the Moderna vaccine, and three weeks for those who receive Pfizer.  As the number of first doses being administered has increased over the past several weeks, now the number of doses needed for the second shot are also increasing.  Therefore, the amount of vaccine available to be administered as a first dose must decrease.  Over the next several weeks, as the number of first doses administered decreases to account for the limited amount of vaccine, we will begin to see a balancing of vaccine available for both doses.

We will continue to work with our local health departments and other providers to help them balance vaccine doses as production of the vaccine begins to ramp up and additional vaccines come online.  For more information on COVID-19 vaccines and how to make an appointment visit