Continuous Temperature Monitoring

• Vital to proper vaccine storage

• Twice a day “manual check” system:

• Possible false alarm if checked during

defrost cycle

• Failure to recognize existence of

defrost cycle and take any necessary

protective measures

• Freezerless fridge example

• Cumulative effect of time above 8 °C

during multiple defrost cycles?

• Evaluate on case-by-case basis

• Monitor placement is very important!

-1

2

5

8

11

14

17

0:00 0:15 0:30 0:45 1:00

Duration of measurement, h:min

Tem

pera

ture

, °C

1 (top wall)

2 (mid wall)

3 (bottom wall)

4 (top back wall)

5 (air)

6 (vial - floor)

7 (air)

8 (air)

9 (air - top)

10 (in box)

11 (in box)

12 (vial - mid)

13 (vial - mid)

14 (inside tray)

15 (back of tray)

17 (glycol - floor)

18 (glycol - mid)

19 (glycol - top)

20 (vial - low)

LA (floor)

LC (mid)

LD (glycol - top)

WITHOUT a continuous temperature monitoring system in place..

– Likelihood of undiscovered thermal excursions occurring is VERY HIGH

Examples: overnight power outage, excessive refrigerator cooling following long or

frequent periods of door opening, defrost cycle patterns

– Likelihood of administering spoiled, ineffective vaccines to patients is VERY HIGH

– By the time temperature deviations are found, may be too late for corrective action

– No way to tell when a problem started, how long it lasted,

…or whether the vaccine is safe!

Evaluating Electronic Data Logging Thermometers

Reference thermocouple in glycol-filled bottle – Glycol approximates thermal mass and properties of liquid vaccine

Average temperatures recorded by data loggers with probes in glycol matched ref TC

measurements more closely than loggers recording air temperature – Air temperature sensors: less thermal mass → more susceptible to small temperature

fluctuations, less representative of vaccine temperatures

Data loggers with probes in glycol

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

LD probe LE1 probe LE2 probe LF probe LG probe

ΔT

(°C

)

2 °C

4 °C

6 °C

8 °C

10 °C

Data loggers recording air temperature

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

LA LB LC LD internal LG internal

ΔT

(°C

)

2 °C

4 °C

6 °C

8 °C

10 °C

Selecting a Digital Data Logger Thermometer

for Vaccine Temperature Monitoring

Main readout unit

(temperature display)

External, detachable temperature probe

False Alarm Alert:

Thermometer Placement

Matters!

Sensors in air, attached to walls, or

near cooling vents show temperature

spikes > 8 °C in all refrigerator types

Freezerless Refrigerator Door Opening Trial

0

2

4

6

8

10

12

14

16

0:00 0:15 0:30 0:45 1:00 1:15 1:30 1:45

Duration of measurement, h:min

Te

mp

era

ture

, °C

1 (top wall)

2 (mid wall)

3 (bottom wall)

4 (top back wall)

5 (air)

6 (vial - floor)

7 (air)

8 (air)

9 (air - top)

10 (in box)

11 (in box)

12 (vial - mid)

13 (vial - mid)

14 (inside tray)

15 (back of tray)

17 (glycol - floor)

18 (glycol - mid)

19 (glycol - top)

20 (vial - low)

Dual Zone Refirgerator Door Opening Trial

0

2

4

6

8

10

12

14

16

10:45 11:00 11:15 11:30 11:45 12:00 12:15 12:30 12:45 13:00

Time, h:min

Te

mp

era

ture

, °C

1 (top wall)

4 (top back wall)

5 (air - deli drawer)

7 (air)

8 (air)

9 (air - top)

15 (back of tray)

19 (glycol - top)

TC #19 (magenta) shows

temperature < 2 °C

– Inside glycol-filled bottle, directly on

glass shelf under cooling vent

– Repeated door opening results in

driving temp down

– Monitor placed in this location NOT

a good indicator of stored vaccine

temperature – nor is this a good

location to store vaccine!

Data Logger Installation

Attach logger display to

outside of refrigerator

Place logger probe and bottle setup in a tray in

the center of the refrigerator. Fix bottle in place

with tape or Velcro, or use a bottle stand.

Cable is not thick

enough to affect

refrigerator temperature

Downloading Logger Data

When should I download logger data?

– At least once per week, at the same time each week (e.g., Monday morning)

– Any time a high or low temperature alarm is activated, download data

immediately, even if it is not the scheduled download time

Downloading procedure

– Leave the probe in glycol setup

undisturbed inside the refrigerator

– Disconnect logger readout unit from

probe cable

– Connect readout unit to computer via

USB cable or cradle

– Open logger software and select option

to stop logger and download data

– Save the data file with an appropriate,

standardized name which indicates the

data collection date range (e.g. Fridge1

Aug 14-20 2010.xls)

– Restart logger and reconnect to probe

Reviewing Logger Data After data download, review logger reports/graphs to determine if any thermal

excursions (temperatures outside the 2 °C to 8 °C range) have occurred

Green arrows show temperature spikes caused

by defrost cycle (~36 h intervals), but logger

temperature has remained within 2 °C to 8 °C

If an excursion has occurred…

– Determine when it started, its duration,

and the maximum or minimum

temperature reached

– Try to determine the cause (e.g. power

outage, door left open too long,

problem with refrigerator set point

stability, defrost cycle)

– Provide this information to VFC

coordinator/ vaccine manufacturer for

guidance on how to proceed

Yellow arrow shows a thermal excursion lasting

2 h 20 min, with max. temperature = 16 °C

This excursion was caused by a staff member

accidentally leaving the fridge door open for 1 h

Phase 3: Measurements in Progress

Determine optimal methodology and refine guidelines for

temperature monitoring of vaccines

Optimal data logger probe setup – tracks temperature of

vaccine fluid inside a vial or syringe kept in its original

packaging (fine-gauge thermocouples inside vials/syringes

provide accurate reference temperature)

Identify suitable sample medium(s): glycol, glycol/water, glass

beads, sand, air in vial

Immersion requirements: sample volume/vial size for different

types and sizes of probes

Impact of variable conditions: door opening, cooling/defrost

cycles, and power outages

Dual-zone case study highlights need for in-depth study of frozen vaccine storage Freezer systems currently used for vaccine storage have not been adequately characterized for this

purpose, making selection of suitable and reliable systems problematic

Evaluate common types of frozen vaccine storage systems: upright stand-alone freezer, dual-zone

(top, swinging door freezer), dual-zone (bottom pull-out drawer freezer), pharmaceutical grade,

chest and portable freezer/coolers

Characterize transport containers and pack-outs for

short-term emergency transport of refrigerated and

frozen vaccines

References & Additional Resources

NIST Vaccine Storage and Temperature Monitoring Webpage:

http://www.nist.gov/pml/div685/grp01/vaccines.cfm

NIST IR 7753 – Thermal Analysis of Household Refrigerator/Freezer and

Pharmaceutical Refrigerator for Vaccine Storage

NIST IR 7565 – Thermal Analysis of a Dorm-style Refrigerator and Freezerless

Refrigerator for Vaccine Storage

NIST IR 7899 - Data Logger Thermometers for Vaccine Temperature Monitoring

NIST IR 7900 - Thermal Analysis of a Small Pharmaceutical Refrigerator for

Vaccine Storage

Guidelines for Storage and Temperature Monitoring of Refrigerated Vaccines

Assessing the Use of Infrared Thermometers for Vaccine Temperature

Determination

Thank You!

Many thanks to the Virginia and DC VFC

Programs for their contributions to this study.

Additional thanks to Patricia Beckenhaupt,

Tony Richardson, and the Centers for Disease

Control for their work in supporting this project.