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DDL Switch Out Delay

DDL Switch Out Delay

Dear VFC Provider:

Your DLL(s) may need to be re-calibrated. Under routine guidelines, the Philadelphia Department of Public Health (PDPH) would replace your old DDL(s) with a newly calibrated DDL(s). However, we are currently unable to replace DDLs due to manufacturing difficulties caused by the COVID-19 pandemic.

Recognizing this, the CDC has released updated guidance regarding the use of DDLs. The CDC is allowing the use of DDLs for up to 2 years from the expired calibration date. After consulting with the DDL manufacturers and DDL experts, the CDC is confident that DDLs that have recently reached the 2 years post-expired calibration date would still operate with the accuracy to suffice the CDC required parameters for storage and handling.

This allowance is applicable to PDPH provided DDLs.

PDPH is committed to always preserving the viability of vaccines. As soon as the shortages in the DDL market improve, PDPH will move forward with the usual biannual swap out. We’ll contact you when the newly recalibrated DDLs are mailed out to your site.

Until then, please let us know if your DDL displays a low battery symbol (pictured below) or is experiencing any other issues by emailing us at or calling us at 215-685-6424.


Thank you for patience and understanding as we grow the Philadelphia vaccine distribution network.

Please feel free to contact us with any questions or concerns.


The Immunization Storage & Handling Team