PURPOSE: There is currently no systematically available information available on how rapidly a specific lot of vaccine is used once distributed. We used data from reports to the Vaccine Adverse Event Reporting System (VAERS) to develop a proxy means of surveillance for the lifecycle of selected vaccine lots. METHODS: A convenience sample, consisting of selected lots of: diphtheria, tetanus, and acellular pertussis (DTaP), Haemophilus influenzae type b (Hib), Hepatitis B, and varicella vaccines, was selected for lifecycle analysis. Assuming that circulation of a vaccine lot is proportional to vaccine-specific adverse event (AE) reporting for that vaccine type, we constructed Gamma distributed usage models and compared them with lot-specific VAERS reports to estimate the actual lifecycle of lots in the system. RESULTS: Evidence of lot circulation was detected within 1-2 months, and a peak was observed 3-4 months after the vaccine release date for most of the study vaccines. Ninety percent of the vaccine doses in each lot were estimated to be used within 5-9 months of distribution. The length of time a vaccine lot was in use ranged from 5 to 17 months from earliest vaccination date. CONCLUSIONS: Our modeled and inferred administration of the selected lots of different vaccines were concordant. This method may be useful for spatial and temporal tracking of vaccine lot utilization.
PURPOSE: There is currently no systematically available information available on how rapidly a specific lot of vaccine is used once distributed. We used data from reports to the Vaccine Adverse Event Reporting System (VAERS) to develop a proxy means of surveillance for the lifecycle of selected vaccine lots. METHODS: A convenience sample, consisting of selected lots of: diphtheria, tetanus, and acellular pertussis (DTaP), Haemophilus influenzae type b (Hib), Hepatitis B, and varicella vaccines, was selected for lifecycle analysis. Assuming that circulation of a vaccine lot is proportional to vaccine-specific adverse event (AE) reporting for that vaccine type, we constructed Gamma distributed usage models and compared them with lot-specific VAERS reports to estimate the actual lifecycle of lots in the system. RESULTS: Evidence of lot circulation was detected within 1-2 months, and a peak was observed 3-4 months after the vaccine release date for most of the study vaccines. Ninety percent of the vaccine doses in each lot were estimated to be used within 5-9 months of distribution. The length of time a vaccine lot was in use ranged from 5 to 17 months from earliest vaccination date. CONCLUSIONS: Our modeled and inferred administration of the selected lots of different vaccines were concordant. This method may be useful for spatial and temporal tracking of vaccine lot utilization.
Authors: George E Moore; Michael P Ward; Martin Kulldorff; Richard J Caldanaro; Lynn F Guptill; Hugh B Lewis; Lawrence T Glickman Journal: Vaccine Date: 2005-08-08 Impact factor: 3.641