How can officials ensure the new COVID-19 vaccines aren’t damaged by heat as they move by plane, train, truck or automobile to all ends of the world?
Vaccines are sensitive to temperature. The Pfizer vaccine, for example, must be kept extremely cold: minus 70 degrees Celsius, a temperature typically found in Antarctica, the coldest place on Earth.
Vaccine manufacturers say they are meeting the challenge of keeping the vaccines safe, but some experts warn the vaccines could become degraded in areas where cold storage is not readily available.
“This is very important,” said Ray Baughman, a University of Texas at Dallas chemistry professor who helped develop technology widely used on vaccine vial labels that monitor whether the vials have been exposed to too much heat, rendering the vaccine ineffective.
“Time and temperature affects vaccine viability,” Baughman said.
Vaccines shipping out
Pfizer has said its vaccine is 95% effective in preventing contraction of COVID-19, the illness associated with the new coronavirus. Moderna, another biotechnology company developing a COVID-19 vaccine, said its candidate is 94% effective.
Like Pfizer’s, Moderna’s vaccine must also be kept in extreme cold, at minus 20 degrees Celsius.
Pfizer started shipping COVID-19 vaccines in the U.S. on Sunday after receiving emergency authorization from the FDA. Dallas started receiving shipments Monday morning.
A Pfizer representative said the drug developer will use GPS-enabled thermal sensors in every container of vaccines to track the location and temperature of each vaccine shipment.
“These GPS-enabled devices will allow Pfizer to proactively prevent unwanted deviations and act before they happen,” said Francesca Marzullo, manager of Pfizer Global Supply Communications.
But the sensors aren’t on each individual vial.
“These electronic temperature sensors are typically used for large shipments of vaccines that are going from the manufacturer to the places where these vaccines are locally distributed,” Baughman said. “They are not used on individual vaccine vials.”
Threat to vaccines
The biggest threat to the vaccines is after these large shipments are divided up for delivery to local vaccination sites, especially in remote areas where the advanced refrigeration might not be available.
“Individual vaccine vials are not flawlessly protected from thermal degradation caused by possible too long an exposure at too high temperatures,” unless vaccine vial monitors are used, he said.
Baughman developed the technology for vaccine vial monitors, or VVMs, in the 1970s when he was leading a group at Allied Corporation in New Jersey. They discovered that a particular polymer-based chemical could monitor exposure to heat over a period of time.
The product proved perfect for monitoring vaccines. At the time, one of the biggest obstacles facing those involved in mass vaccination programs was managing the temperature of the vaccines as they traveled to remote locations, sometimes to places accessible only by a donkey.
Monitoring and managing the temperature of vaccines during the distribution process was historically one of the biggest challenges for immunization programs.
Before the monitors existed, there was no way of knowing whether a vial of vaccine had been exposed to heat, degrading it. In some cases, perfectly good vaccines would have been tossed out if it was suspected that they’d been affected by heat, Baughman said.
The first vaccine vial monitors were used in 1996 with oral polio vaccine. Since then, the vial monitors have been adopted by the World Health Organization as part of its effort to immunize the world’s population against diphtheria, whooping cough, tetanus, measles, polio and other diseases.
The vial monitors are especially needed in developing countries where refrigeration and cold storage are not always available.
The vaccine vial monitors “helped to change how immunization is done around the world,” said Ted Prusik co-founder of Temptime, which provides individual vaccine vial monitors to the World Health Organization for its worldwide immunization project.
‘The unreached child’
The vial monitors have changed the logistics of getting vaccines to “the unreached child” in remote areas where there wasn’t refrigeration, Prusik said.
“Now with these [vial monitors] you can do that, and do it with confidence,” he said.
Temptime, based in Morris Plains, N.J., and owned by Zebra Technologies, has sold more than 8 billion vial monitors since 1996, or about 600 million a year. Because each vial contains multiple doses, the vial temperature monitors have ensured the safety of literally tens of billions of doses of vaccine.
Each unit looks like an ink dot on the vial label and costs about 6 cents each, said Baughman.
Vaccine vial monitors are being considered for Operation Warp Speed, the public-private partnership initiated by the U.S. government to fight COVID-19, officials said.
Vaccine vial monitors are part of ongoing Operation Warp Speed discussions about future distributions of the vaccine, Prusik said.
“This first wave of vaccines that’s come out from Pfizer, there are no VVMs on there,” he said.
“Larger volumes will be coming further down the road. And that’s primarily our focus now is to make sure we get on the larger volumes in developing countries but also developed countries,” he said.
Dr. James Cutrell, associate professor of internal medicine in the division of infectious diseases and geographic medicine at UT Southwestern Medical Center, said he doesn’t “have major concerns” about possible heat damage to the vaccine vials.
Pfizer’s thermal shippers hold about 1,000 vials of vaccines and dry ice to keep them cold. The shippers, which are about the size of a suitcase, contain a GPS-enabled thermal sensor, which lets Pfizer track the location of the containers and their temperature.
Once a shipment gets to the location, the container of vaccine is immediately put into an ultra-low-temperature freezer, where it can be stored for up to six months, Cutrell said.
Even without such freezers, the container will remain safe for up to a month if you add dry ice every five days,” Cutrell said.
Once the vaccine is thawed, “you have about five or six hours to use it,” he said.
Developing countries
Baughman, the UTD professor, said temperature monitoring is even more critical in developing countries, which often don’t have the ultra-cold storage capacity available in developed countries, like the United States.
In a commentary published in the Oct. 21 issue of the journal Vaccine, Baughman urged COVID-19 vaccine developers to make publicly available the thermal data of their vaccines so that companies that make the vaccine vial monitors, such as Temptime, can produce the appropriate labels in time for widespread distribution.
“Our immediate request is that developers of COVID-19 vaccines make publicly available detailed information on the effects of time and temperature on vaccine potency even before human trials are completed, so that all potential time-temperature indicator developers have time to produce reliable indicators,” Baughman and co-author Dr. John R. Allegra, an emergency medicine physician, wrote.
Confidence in the vaccines is important — especially at a time when trust in immunizations has dropped, even in countries like the United States, where many diseases have been eradicated by vaccines.
“Hopefully VVMs will help to change that and make sure everybody knows that the vaccine dose they’re getting has not been exposed to excessive heat,” Prusik said.
