Risk factors for improper vaccine storage and handling in private provideroffices

Context. Preventing loss of vaccine potency during storage and handling is increasingly important as new, more expensive vaccines are introduced, in a t least 1 case requiring a different approach to storage. Little informatio n is available about the extent to which staff in private physicians' offic es meet quality assurance needs for vaccines or have the necessary equipmen t. Although the National Immunization Program at the Centers for Disease Co ntrol and Prevention (CDC) in 1997 developed a draft manual to promote reli able vaccine storage and to supplement published information already availa ble from the CDC and the American Academy of Pediatrics, the best ways to i mprove vaccine storage and handling have not been defined. Objectives. To estimate the statewide prevalence of offices with suboptimal storage and handling, to identify the risk factors for suboptimal situatio ns in the offices of private physicians, and to evaluate whether the distri bution of a new National Immunization Program draft manual improved storage and handling practices. Design. Population-based survey, including site visits to a stratified, ran dom sample of consenting private physicians' offices. At least 2 months bef ore the site visits, nearly half (intervention group) of the offices were r andomly selected to receive a draft CDC manual entitled, "Guideline for Vac cine Storage and Handling." The remainder was considered the control group. Trained graduate students conducted site visits, all being blinded to whet her offices were in the intervention or control groups. Each site visit inc luded measurements of refrigerator and freezer temperatures with digital th ermometers (Digi-thermo, Model 15-077-8B, Control Company, Friendswood, TX; specified accuracy +/- 1 degreesC). Their metal-tipped probes were left in the center shelf of cold storage compartments for at least 20 minutes to a llow them to stabilize. The type of refrigerator/freezer unit, temperature- monitoring equipment, and records were noted, as were the locations of vacc ines in refrigerator and freezer, and the presence of expired vaccines. Oth er information collected included the following: staff training, use of wri tten guidelines, receipt of vaccine deliveries, management of problems, num ber of patients, type of office, type of medical specialty, and the profess ional educational level of the individual designated as vaccine coordinator . Participants. Two hundred twenty-one private physicians' offices known by t he Georgia Immunization Program in 1997 to immunize children routinely with government-provided vaccines. Outcome Measures. Estimates (prevalence, 95% confidence interval [CI]) of i mmunization sites found to have a suboptimally stored vaccine at a single p oint in time, defined as: vaccine past expiration date, at a temperature of less than or equal to1 degreesC or greater than or equal to9 degreesC in a refrigerator or greater than or equal to -14 degreesC (recommended for var icella vaccine) in freezer, and odds ratios (ORs) for risk factors associat ed with outcomes. We performed chi (2) analysis and Student's t tests to co mpare the administrative characteristics and quality assurance practices of offices with optimal vaccine storage with those with suboptimal storage, a nd to compare the proportion of offices with suboptimal storage practices i n the groups that did and did not receive the CDC manual. Results. Statewide estimates of offices with at least 1 type of suboptimal vaccine storage included: freezer temperatures measuring greater than or eq ual to -14 degreesC = 17% (95% CI: 10.98, 23.06); offices with refrigerator temperatures greater than or equal to9 degreesC = 4.5% (95% CI: 1.08, 7.86 ); offices with expired vaccines = 9% (95% CI: 4.51, 13.37); and offices wi th at least 1 documented storage problem, 44% (95% CI: 35.79, 51.23). Major risk factors associated with vaccine storage outside recommended temperatu re ranges were: lack of thermometer in freezer (OR: 7.15; 95% CI: 3.46, 14. 60); use of freezer compartment in small cold storage units (OR: 5.46; 95% CI = 2.70, 10.99); lack of thermometer in refrigerator (OR: 3.07; 95% CI: 1 .15,8.20); and failure to maintain temperature log of freezer (OR: 2.70; 95 % CI: 1.40, 5.23). Offices that adhered to daily temperature monitoring for all vaccine cold storage compartments, compared with those that did not, w ere 2 to 3 times more likely to assign this task to staff with higher level s of training, have received a recent visit from the state immunization pro gram, and be affiliated with a hospital or have Federally Qualified Health Center status. In addition, sites using >1 refrigerator/freezer for vaccine storage were more likely to have at least 1 cold storage compartment outsi de recommended temperature ranges. We found no significant differences in t he data reported above between the intervention group (received copy of the draft manual) and the control group (did not receive copy of draft manual) , even when controlling for the annual number of immunizations given or the type of office. Conclusions. Problems with vaccine storage are common and mainly relate to inadequate monitoring of cold storage units or use of freezer units in inap propriate, small refrigerator/freezer units. A modest outlay to purchase eq uipment and/or train staff could avoid these problems. These results suppor t the following steps: 1) do not store frozen vaccines in freezer compartme nts in less than full-sized refrigerators (< 18 cu ft); 2) monitor temperat ures in both the refrigerator and freezer compartments to ensure that setti ng the freezer compartment control to <-15 degreesC does not lower the refr igerator compartment to <2<degrees>C and thereby freeze vaccines that may b e damaged by such exposure; 3) prepare a written job description for the du ties of vaccine coordinator; 4) review temperature-monitoring practices; 5) follow standard procedures when vaccine temperatures are out of range or a power outage occurs; 6) inventory and rotate vaccines in cold storage each time new vaccines are delivered; and 7) train all vaccine-handling staff i n the above and ensure that all have access to the latest authoritative gui dance on vaccine storage and that all understand the meaning of temperature range, negative temperatures, Celsius and Fahrenheit scales, and conversio n.