Which of the following best explains the purpose of using water bottles in the fridge for vaccines?

• A. They serve as placeholders.
• B. They help stabilize temperature.
• C. They increase humidity.
• D. They replace ice packs.

Answer: (B)

Maintaining a stable fridge temperature is essential when storing vaccines. Water bottles act as thermal mass: they absorb heat when the door is opened or the surrounding room is warm, slowing the rise in temperature inside the fridge. As the internal temperature tends to fall, the bottles release heat, helping prevent temperatures from dropping too low. This buffering reduces excursions outside the recommended 2–8°C range, protecting vaccine potency. They’re not simply placeholders or meant to raise humidity, and they don’t replace ice packs; the bottles support temperature stability as part of the cold chain strategy.