Image copyright Senate Research Service Image caption Scientists are using a US service to do this
Vaccines produced in England are making a potentially important contribution to US vaccine stocks, according to a new study.
Researchers tracked the tracking of three vaccines for the European Influenza Vaccine Group (EIVG) after commercialisation in the UK and US.
The best examples of long-distance tracking for vaccines was for the A/H1N1 swine flu vaccination, which was made in Bristol.
Researchers also tracked two doses of a meningitis and bacterial pneumonia vaccine which are produced in South Africa.
These tracking studies are run by the Senate Research Service (SRS), a branch of the US Congress which has an agreed research programme to monitor new vaccines in America for protection against swine flu, dengue, Japanese encephalitis and yellow fever.
For swine flu, scientists tracked each UK shipment of vaccine through the US Customs and Border Protection (CBP) system, which is publicised by US border authorities, who pass them on to state and local authorities.
In the US, CBP helps local officials track vaccine shipments and shipment dates, but states can set up their own tracking systems through their local health departments.
Image copyright CDC Image caption Swine flu vaccine is now imported into the US using the same tracking system
After a single supply batch of the vaccine was distributed to 36 states in November 2014, data on who got the vaccine became publicly available, showing a high level of confirmed vaccination.
After this batch was shipped, the SRS followed the CDC Rapid Supply Tracker, which uses a similar method to track the supply of vaccines, to see how they arrived in the US and entered stockrooms.
The data from this team tracked 1,123 shipments from the three vaccine facilities to the US between December 2014 and May 2016.
The research showed:
The vaccine in the UK arrived in the US 11 days earlier than it was approved for vaccination in the UK
One container was caught flying to the US in early January 2015, before being cleared by CBP and heading on to the containerships that brought the vaccine to the US
All trivalent vaccines were delivered more than two days early
CDC required provincial health departments to regularly update their vaccine ordering status on its database
The SRS tracks swine flu vaccines in America
Image copyright Dept of Agriculture/CDC Image caption Meningitis B vaccine is produced in South Africa
In the case of Meningitis B vaccine, researchers tracked shipments arriving at two of the North American factories.
The first batch was produced in South Africa in 2004 and shipped to the Americas in 2010. The second batch was produced in South Africa in 2013 and delivered to North America in 2015.
Following the research, the CDC says: “Taken together, these data have allowed CDC to confirm that Meningitis B vaccine was produced in the only two CDC authorized facilities in the Americas, that it was produced by at least one of the manufacturers, and that it has been administered to 2.5 million Americans.”