Keeping Their Cool

When you visit your doctor for a flu shot or other vaccine, you might not consider that the vaccine had to travel to your doctor’s office, too, from the place where it was originally made. And on its way, it had to be kept within a narrow temperature range – not too hot and not too cold – to stay effective.

The problem of keeping vaccines cool while traveling is serious. There are 7.4 billion people on the planet, and millions need vaccine shots at any given time. But it turns out that as much as 35% of all the vaccines shipped worldwide are wasted because they are not stored within this strict range of temperatures during the trip.

In the United States, the problem had become so acute by 2009 that the Centers for Disease Control and Prevention (CDC) – which distributes about $4 billion worth of vaccines every year through its Vaccines for Children program – asked PML staff to help figure out better ways to keep vaccines cool as they travel.

“Vaccines can go bad if stored improperly,” says Michal Chojnacky, who is leading PML’s work. “If this happens and no one detects it, you run the risk of delivering ineffective vaccines to patients. The other danger is thinking that a vaccine goes bad when it doesn’t. And if that happens, then you waste the cost, and you potentially delay vaccines getting to the intended patients.”

To identify where the “problem areas” are in transportation, Chojnacky and colleagues try to replicate everyday practices of vaccine providers and come up with workarounds. So far, they have created new tools and training materials such as the “CDC vaccine toolkit”. Chojnacky is also developing a way to use coolers to safely transport vaccines during power outages and other emergencies.

Furthermore, it turns out that there are no reliable answers to even basic questions yet about how clinic workers use their vaccine fridges and freezers. For example, every time a clinic worker takes a vaccine out of a storage unit, the temperature inside rises. But how often do doctors and nurses access these fridges each day? And how long do they need to keep the doors open?

No one knows yet, so PML is trying to find out. In one early study looking at pediatricians’ offices around the U.S., PML researchers found that health workers open vaccine fridge doors for an average of just a few seconds at a time, which was significantly less than expected. With more data, scientists hope to make new guidelines that can be used to test refrigerators and freezers, to make sure they are appropriate for vaccine storage.