System [both described in detail below], the Vaccine Adverse Events Reporting System, inquiries received through CDC’s Clinician Information Line, and requests for vaccinia immune globulin and cidofovir), data on adverse events will be linked to a vaccinee’s record in PVS using the vaccinee’s Patient Vaccination Number (PVN). A case investigation of the adverse event will involve a reevaluation of whether the vaccinee had any contraindications that were not disclosed initially or were not recognized at the time. Because contraindications will be part of the case investigation, and it is possible that revisions will be made to the list of contraindications as the vaccination program moves forward, it will be necessary to know which version of the Pre-Vaccination Information Packet the vaccinee received. The committee recommends that a data field be added to PVS to indicate which version of the Pre-Vaccination Information Packet was provided to the vaccinee, in order to document what information was given to the vaccinee prior to consent.
CDC has proposed conducting a telephone follow-up survey of 10,000 vaccinees in eight states to study the rate of common adverse reactions in vaccinees and the average amount of time lost from work due to reactions to the vaccine. CDC plans to use a stratified sampling scheme to ensure adequate representation of men and women and primary vaccinees and revaccinees. The planned survey should provide valuable information about the rate of common adverse reactions in vaccinees, and the committee is pleased that CDC has designed a method for gathering these data.
CDC proposes to use an internal comparison/“control” group to control for the rates of common health events that will be observed during the course of this study. Since, in the context of the smallpox vaccination program, the health status of unvaccinated persons may differ significantly from vaccinees (i.e., due to contraindications), CDC proposes to use a comparison group exposed to the vaccine as a “control” group. CDC assumes that common adverse reactions associated with the vaccine will resolve by day 30 post-vaccination. Working under this assumption, the “control” group will be drawn from vaccinees who agreed to participate in the survey but were not selected for the sample. These “controls” will be observed for 21 days (the same length of time that the “treatment” group will be observed) following day 30 post-vaccination. The “controls” will receive the same diary card (for recall purposes) that is used by the “treatment” group (updated to reflect the different observation period), and will be observed for the 21 day period when they are assumed to experience “normal” health events (i.e., not due to the vaccine, since health events due to the vaccine are assumed to resolve by day 30 post-vaccination).