Most of the production for Pfizer's COVID-19 is manufactured at their facility in Puurs, Belgium (essentially next door to the Netherlands). Shipping it at extreme cold temps to the islands which make up the Kingdom of the Nertherlands should be very achievable so my guess is that it will be the Pfizer vaccine arriving in SXM. I would hope that the St. Maarten Medical Center near Philipsburg would have freezer capabilities that could store the vaccine at negative 70 celsius. Storing vaccines at extremely cold temperatures in actually nothing new (though -70 celsius has to be a some kind of record!). Other vaccines such as those for Chicken Pox and Measles, Mumps & Rubella are stored at temperatures as low as -50 celsius before they are warmed up to room temperature and administered. I would think those common vaccines have been stored and given on St. Maarten in the past without incident.