PEDIATRICS Vol. 107 No. 6
June 2001,
p. e100
ELECTRONIC ARTICLE:
Risk Factors for Improper Vaccine Storage and Handling in
Private Provider Offices
Received Aug 4, 2000; accepted Jan 22, 2001.
Karen N. Bell*, 
,
Carol J. R. Hogue*, ,
Claudine Manning*, §, and
Alan P. Kendal*
From the * Women's and Children's Center; and the Departments
of Epidemiology and § Biostatistics, Rollins School of Public
Health, Emory University, Atlanta, Georgia.
Context. Preventing loss of vaccine
potency during storage and handling is increasingly important as new,
more expensive vaccines are introduced, in at least 1 case requiring a
different approach to storage. Little information is available about
the extent to which staff in private physicians' offices meet quality
assurance needs for vaccines or have the necessary equipment. Although
the National Immunization Program at the Centers for Disease Control and Prevention (CDC) in 1997 developed a draft manual to promote reliable vaccine storage and to supplement published information already available from the CDC and the American Academy of Pediatrics, the best ways to improve 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 situations in the offices of private physicians,
and to evaluate whether the distribution of a new National Immunization
Program draft manual improved storage and handling practices.
Design. Population-based survey, including site visits to
a stratified, random sample of consenting private physicians' offices.
At least 2 months before the site visits, nearly half (intervention group) of the offices were randomly selected to receive a draft CDC
manual entitled, "Guideline for Vaccine Storage and Handling." The
remainder was considered the control group. Trained graduate students
conducted site visits, all being blinded to whether offices were in the
intervention or control groups. Each site visit included measurements
of refrigerator and freezer temperatures with digital thermometers
(Digi-thermo, Model 15-077-8B, Control Company,
Friendswood, TX; specified accuracy ± 1°C). Their metal-tipped
probes were left in the center shelf of cold storage compartments for
at least 20 minutes to allow them to stabilize. The type of
refrigerator/freezer unit, temperature-monitoring equipment, and
records were noted, as were the locations of vaccines in refrigerator
and freezer, and the presence of expired vaccines. Other information
collected included the following: staff training, use of written
guidelines, receipt of vaccine deliveries, management of problems,
number of patients, type of office, type of medical specialty, and the professional educational level of the individual designated as vaccine
coordinator.
Participants. Two hundred twenty-one private physicians'
offices known by the Georgia Immunization Program in 1997 to immunize
children routinely with government-provided vaccines.
Outcome Measures. Estimates (prevalence, 95% confidence
interval [CI]) of immunization sites found to have a suboptimally
stored vaccine at a single point in time, defined as: vaccine past
expiration date, at a temperature of 
1°C or 
9°C in a
refrigerator or 
14°C (recommended for varicella vaccine) in
freezer, and odds ratios (ORs) for risk factors associated with
outcomes. We performed 
2 analysis and Student's t
tests to compare the administrative characteristics and quality
assurance practices of offices with optimal vaccine storage with those
with suboptimal storage, and to compare the proportion of offices with
suboptimal storage practices in 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 14°C = 17% (95% CI: 10.98, 23.06); offices with
refrigerator temperatures 9°C = 4.5% (95% CI: 1.08, 7.86);
offices with expired vaccines = 9% (95% CI: 4.51, 13.37); and
offices with at least 1 documented storage problem, 44% (95% CI:
35.79, 51.23). Major risk factors associated with vaccine storage
outside recommended temperature 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, were 2 to 3 times more likely to assign this task to staff with
higher levels of training, have received a recent visit from the state immunization program, 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 outside recommended temperature ranges. We found no significant differences in the 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 inappropriate, small refrigerator/freezer units. A
modest outlay to purchase equipment and/or train staff could avoid
these problems. These results support the following steps: 1) do not store frozen vaccines in freezer compartments in less than full-sized refrigerators (<18 cu ft); 2) monitor temperatures in both the refrigerator and freezer compartments to ensure that setting the freezer compartment control to <15°C does not lower the
refrigerator compartment to <2°C and thereby freeze vaccines that
may be damaged by such exposure; 3) prepare a written job description
for the duties 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 in the above and ensure that all have access to
the latest authoritative guidance on vaccine storage and that all
understand the meaning of temperature range, negative temperatures,
Celsius and Fahrenheit scales, and conversion.
Key words:
vaccine
storage,
immunization practices,
immunization guidelines,
cold chain,
quality assurance.
