As the UAE's vaccine drive began on December 22, a crucial religious ruling was sent out: the vaccine is halal. The UAE Fatwa Council was one of the first Islamic authorities to deliver that view – an hour after the Pfizer-BioNTech vaccine was approved in Dubai. The ruling came as scholars across the Muslim world looked for guidance. The issue is this: for years pork gelatin has been used in some vaccines as a stabilising agent, ensuring a vaccine remains safe and effective in storage. Many scholars have now said the substance used in some of the shots is medicine, not a foodstuff – and the need to save life overrides any normal religious observance, such as the prohibition of pork. On Saturday, Indonesia, which has the world's largest Muslim population, also said that the vaccine is halal. But the issue remains complex and has been marred by fake news and myths. Here we clarify the latest thinking. For years, vaccines and other drugs have contained gelatin, a substance derived from the collagen of animals such as chicken, cattle, pigs and fish. 'Porcine gelatin' is derived from pigs. Gelatin is used in a wide variety of medicines, including capsules and some vaccines. In vaccines, the substance is used as a stabiliser to ensure the liquid remains safe and effective when stored. Unlike the gelatin used in foods – is it often found in jelly sweets, desserts and fruit snacks – it is highly purified and broken down into small molecules called peptides. Many Muslim scholars do not regard this as consuming pork products. Yes. In recent years the need to satisfy religious observance, particularly for Muslims and Jews, has led to the use of alternatives to gelatin. The UK government agency Public Health England says that Fluenz Tetra, the nasal spray vaccine that protects children against flu; MMR VaxPro, which protects against measles, mumps and rubella; and Zostavax, which protects older adults against shingles, all contain porcine gelatin. The MMR vaccine has a non-porcine alternative. At this time, the others do not. The vaccines created to protect people against the new coronavirus were the fastest ever created. And, once scientists have an effective stabiliser and test it with a vaccine, any change would require extensive lab work and clinical studies. As Public Health England notes: "Developing a new, safe and effective vaccine with a different stabiliser may take several years or may never happen." This is where it gets complicated. The common use of gelatin, and the speed at which the shots were introduced in the global drive, means the substance may have been used in a number of vaccines. Drug makers have also been relatively slow to clarify exactly what was used. This is likely to be because the overriding concern is the protection of life above all else, and perhaps out of concern they could confuse the public. It is also for regulators to determine whether to approve a product or not. Chinese pharmaceutical company Sinovac, which trialled its vaccine in Indonesia, assured the public there that the shots were "manufactured free of porcine materials". But when Indonesian clerics needed more details, Sinovac took months to provide them. At the weekend, the religious authorities in Indonesia – which is the hardest hit east Asian nation, with 800,000 cases and more than 23,000 deaths – ruled the vaccine was permissible whatever its halal status, and urged the public to take it. In the face of fake news spread about its vaccine, Pfizer-BioNTech confirmed it "does not contain any components of animal origin". Most vaccine makers have highlighted that the products used were highly refined for medical use, whatever their provenance. In short, none of the above should be of consideration to Muslims. The UAE Fatwa Council acknowledged that there were "growing concerns among Muslims over the halal status of the Covid vaccines", in a statement on December 22, 2020 – the same day the Pfizer-BioNTech vaccine was approved and weeks after Sinopharm was introduced in Abu Dhabi. But it said that even though non-halal ingredients are haram, it is permissible because there are no alternatives, and the substance is not a foodstuff. A coronavirus vaccine is in "compliance with Islamic Sharia’s objectives on the protection of the human body", it said. The judgment is based on several principles in Islam, including the preservation of life and the medical use of various products. Dr Adil Sajwani, an Emirati family medicine doctor and a member of the national awareness team for Covid-19 at the UAE's Ministry of Health and Prevention, urged the public not to be swayed by old beliefs or fake news. “Scholarly opinion has changed now, especially in the UAE," he said. "If the substance is transformed into medicine, it is no longer considered prohibited.”