The first batch of Pfizer-BioNTech vaccines has arrived in Dubai ahead of the start of an extensive inoculation campaign in the emirate. The Ministry of Health announced the emergency registration of the vaccine, which is 95 per cent successful in preventing Covid-19, late on Tuesday. Following that, Dubai's Supreme Committee for Crisis and Disaster Management said a "wide and free vaccination campaign against Covid-19 with the Pfizer vaccine" would start immediately. A video released overnight shows the first containers arriving via an Emirates cargo flight from Brussels. The containers are then placed into a special trailer to keep them ultra-cold on their road journey to Emirates Sky Pharma for storage. The doses must be kept at temperatures of -70°C to prevent the mRNA in them – the technology used to deliver the vaccines – from breaking down. RNA is a molecule that tells cells what to do, and the “m” in mRNA stands for messenger. The vaccine acts as a 'messenger' that delivers instructions to cells about how to respond if they become infected with the coronavirus before disappearing, like Snapchat, or a <em>Mission Impossible</em> message that self-destructs. Keeping the vaccines at -70°C maintains the structure of the mRNA for up to six months. The vaccines are stored in ultra-cold freezers but moving them around the world makes that a lot more complicated. There has never been a vaccine or drug that has required such cold storage before, which meant Pfizer had to develop a special method to transport the doses. The company's suitcase-sized “thermal shipper” is capable of storing vaccines for 10 days. The reusable boxes, which can store up to 5,000 doses, are packed with dry ice and installed with trackers to monitor the location and temperature of the frozen vials. They can be opened twice a day for less than three minutes at a time while maintaining the temperature. Once removed, the vials can be kept at 2-7°C for five days. Like the Sinopharm vaccine, which can be stored at normal refrigeration temperatures, Pfizer’s vaccine must be administered in two doses, 21 days apart. Sinopharm’s vaccine received approval in the UAE in November, after health authorities said it proved 86 per cent effective in preventing Covid-19 in trials. It is now widely available in Abu Dhabi and in select centres in the rest of the country. Analysis also showed the Sinopharm vaccine had a 99 per cent seroconversion rate of neutralising antibodies and 100 per cent effectiveness in preventing moderate and severe cases of the disease. Although the Pfizer vaccine is slightly more effective, at 95 per cent, it does not prevent severe disease, although it appears to lessen the risk. During Pfizer's Phase 3 trial, 10 people became severely ill – one of whom received the actual vaccine. In November, it was announced that Emirates airline would partner with Pfizer to distribute its Covid-19 vaccine. At the time, Emirates' president, Tim Clark said the aviation industry was working on establishing the most efficient way to deliver the vaccines to the market. “The logistics of distribution of this vaccine of this nature, given the conditions under which it has to be shipped – it’s going to be a challenge for the industry,” he said. “We’re working on trying to move this Pfizer vaccine in specially designed containers on our planes, in our holds, and in the cabins, and keeping them at that level through the distribution point.”