Nine months after it was rolled out, the AstraZeneca Covid vaccine has finally reached the Antarctic.
It was flown in this week to immunise the 23 staff members who've been keeping the British Rothera research station running through the polar winter.
This is the most southerly despatch yet for the jabs developed at Oxford University.
Apart from some cases at a Chilean base, Antarctica has been Covid-free.
The international science agencies want to keep it that way.
As the new summer research season approaches, strict health protocols will again be in place.
For example, the crew of the UK's new polar ship, the RRS Sir David Attenborough, will shortly go into quarantine before they head south next month with equipment and supplies.
Getting the AZ vaccine to Rothera involved a mammoth trek - a near 10,000-mile journey that began with a RAF Voyager flight from Brize Norton and included stop-overs in Senegal and the Falklands.
And all the while, the doses had to be kept at their required 2-8C storage temperature in a special transport container.
A small Twin Otter plane was used for the final leg into the British Antarctic Survey's (BAS) Rothera base on Tuesday.
A first dose of the AZ vaccine is now in the arms of the station's scientists, engineers and support staff, administered by the doctor on site. The second jab will be given in four weeks' time.
Rothera has essentially been in lockdown since March when only a core group of staff were retained on the continent to tough out the darkness and atrocious weather that are a feature of polar winters.
They'll now have some immunity when visitors begin to arrive for the summer research season.
"People will start flying in from 20 October onwards, so the 'over-winterers' will have had at least one jab," explained John Eager, the head of polar operations at BAS.
"But we aim still to provide extra assurance. And that means everyone that goes down to the Antarctic stations this year will be doing a 14-day quarantine pre-arrival. It's a real belt and braces approach," he told BBC News.
Rothera winter station leader Matthew Phillips added: "Having been entirely on our own for 205 days, through the Antarctic winter, there is always excitement around station in the days and weeks before the first plane arrives, which marks the end of winter. As well as seeing familiar faces return, we also get our first delivery of mail, as well the first fresh fruit and veg since the end of summer.
"Having Covid vaccines flow in has made that an even more singular experience. Being able to vaccinate people will help keep the station population and Antarctica Covid-free. This puts us in a great position ahead of a busy summer on station and in the field."
This is the furthest south the AstraZeneca vaccine has reached. And it means all continents have now received at least some doses, as have all British Overseas Territories.
These far-flung despatches were organised by the not-for-profit international development organisation, Crown Agents, on behalf of the Foreign Office.
"We've been working since March to send the vaccines out, literally to the ends of the Earth," said Crown Agents' CEO Fergus Drake.
"And often it's taken four or five modes of transport to get to some of these places. Getting the vaccine to the Pitcairn Islands and the 47 individuals there necessitated using a longboat because that's one of the few ways you can land on the islands."
There has been one outbreak of Covid in Antarctica, back in December last year.
Military and maintenance staff developed symptoms at Chile's Bernardo O'Higgins research station, also on the Antarctic Peninsula. They were quickly evacuated and replaced by a Covid-free deployment.