TM Refrigerators/Freezers for Vaccine Storage: Is Separate Better? John Stevenson, Tony Richardson Apr 19, 2010 CDC/OID/NCIRD/ISD

TM Agenda Background Study Objectives Study Methods Preliminary Results Preliminary Conclusions Limitations

TM Investigators CDC –Tony Richardson, John Stevenson, Pascale Wortley, Greg Wallace CO: Cinda Ewing, Marianne Koshak GA: Monica Trigg MS: Regina Irvin, Nicholas Carrena

TM Background Breaches in the vaccine cold chain account for a large proportion of vaccine wastage in the United States. Estimated that vaccine waste costs the Vaccines for Children Program alone about $20 million a year. Hundreds of thousands of doses of vaccines are thrown out annually because of inadvertent exposure to freezing temperatures while being distributed and stored in clinics, hospitals and doctors' offices around the country.

TM Background Combination freezer and refrigerator units used to store vaccine are thought to be an important contributing factor to breaches in the cold chain because adjustments to the freezer temperature can result in temperatures being below acceptable range in the refrigerator portion of the unit. It is hypothesized that separate refrigerator and freezer units would result in a lower incidence of out of range temperatures

TM Background Conventional combination refrigerator/freezer unit are inexpensive, but Are not designed for –Precise temperature control –Uniform temperature distribution

TM Vaccine storage requirements

TM Design constraints Only one fan and evaporator used to cool both refrigerator and freezer compartments

TM Study Objectives Determine provider staff knowledge and attitudes towards cold chain errors Conduct continuous temperature monitoring in a sample of freezer/refrigerator units in participating states to determine frequency of out of range temperatures Determine the extent to which frequency of out of range temperatures decreases when separate freezer and refrigerator units are provided Provide evidence base to make decision whether to recommend use of separate refrigerator and freezer units

TM Methods Recruit 3 state immunization programs Recruit ~ 50 private providers from each site Monitor refrigerator and freezer temps for a 6 month baseline period using electronic temperature loggers measuring temps every 30 minutes At 6 months randomize half of the providers to receive separate refrigerator and freezer units Monitor temps for another 6 months Describe and compare frequency and duration of temperature violations

TM Status 3 sites recruited ~ 140 providers 2 sites have completed the study

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CO1075RE The UNIVARIATE Procedure Variable: Temp Schematic Plots | 52 + | | * | 50 + * | 48 + * | | * | 46 + | 0 | | | | 0 | | 44 + | | | | | | | | | | | 42 + | *--+--* | | | | | | | | 40 + | | 0 | | | | *--+--* 0 | | | 38 + | | * | | | | | | 36 + | | | 34 + | | | 32 + | | | | | | 0 | Period 0 1

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Preliminary Conclusions Highlight value of temperature loggers Separate units appear to improve compliance with storage requirements for vaccines stores in refrigerators Separate units do not guarantee adequate performance

TM Limitations Only a subset of the data were analyzed for this presentation Not a representative sample Have not looked jointly at refrigerator and freezer temperatures Temperatures represent air temperature