Pharmaceutical group Sanofi plans to airlift stocks of influenza vaccine in the UK if other transport routes are disrupted once the country has left the EU.
Hugo Fry, managing director of his UK branch, told BBC Radio 5's Wake Up To Money show that the flu vaccine was impossible to stock.
"We are preparing in different ways and have prepared many different routes to the UK," he said.
"If we have to do it in the end, we will do it by plane."
He added, "We are paying for it, but patients and citizens are our main concern, so we are happy to take this cost and plan."
Sanofi claims to be the second largest source of influenza vaccines in the UK, behind Seqirus and ahead of Mylan.
Although Sanofi plans to keep insulin and vaccine stocks for 12 months, Fry said it was not possible with the flu vaccine.
"You can not store it because it is manufactured at a time of year and that it is only possible to import the month late August / early September," he said.
Last August, Sanofi announced an increase in its inventory by four weeks to allow it to supply drugs for 14 weeks.
Most of the French company's supplies enter the United Kingdom through the Channel Tunnel and disruptions on this route in 2005 during strikes in France caused about four weeks of disruption.
Mr. Fry added, "We are doing everything in our power to ensure that everyone gets their medications and vaccines so they can be reassured and not worry.
He added that the day after Brexit, patients would be able to get their hands on all the drugs that it was possible to store.
Calling process of offers
In the current influenza season, Sanofi has provided more than seven million vaccines in the UK.
There are different vaccines for under-65s in at-risk groups and for over-65s.
Sanofi and Seqirus provide both age groups, while Mylan only has vaccines for the youngest age groups.
A call for tenders has been launched to decide which company will provide vaccines in Scotland and Northern Ireland, while in England and Wales, general practitioners decide who will provide the vaccines.
Calls for tenders for the 2019-2020 influenza season have already been published and doctors are deciding who they want to be their provider.