Demonstrator holding an anti-vaccine placard in east London on in central December 5, 2020.JUSTIN TALLIS | AFP | Getty ImagesLONDON — A perfect storm is brewing as Covid-19 vaccines start to roll out more widely in countries around the world. While many people can’t wait to protect themselves from the virus, some are adamant that they won’t get the jab, leaving populations divided into those that have been vaccinated and those that haven’t. In the U.K., one in five say they are unlikely to take the vaccine, according to YouGov research published in November, citing a variety of different reasons. As a result of the differing views, a debate could start to emerge in 2021. Should any restrictions be imposed on people who choose not to get vaccinated given they can catch and spread the virus?It’s a tricky subject but governments are already looking at introducing systems that would enable authorities, and possibly businesses, to tell if a person has had a Covid vaccine or not.China has launched a health code app that shows whether a person is symptom-free in order to check into a hotel or use the subway. In Chile, citizens that have recovered from the coronavirus have been issued with “virus free” certificates.On Dec. 28, Spain’s Health Minister Salvador Illa said the country will create a registry to show who has refused to be vaccinated and that the database could be shared across Europe.Ethical implicationsIsra Black, a lecturer in law at the University of York, and Lisa Forsberg, a postdoctoral fellow at the University of Oxford who researches medical ethics, told CNBC that it “isn’t easy to say whether it would be ethically permissible for a state to impose restrictions” on people who refuse a jab.The academics said in a joint statement via email that the answer will depend on factors like vaccine supply, the level of vaccination in the population, the nature of the restrictions on vaccine refusers, and how the restrictions are operationalized.”We might think that there are strong, albeit not necessarily decisive, reasons in favor of some limitation on regaining pre-pandemic freedoms for individuals who refuse vaccination for Covid-19, for example, on their freedom to gather,” said Black and Forsberg. “There is the potential for unvaccinated individuals to contract a serious case of coronavirus, which we take would be bad for them, but could also negatively affect others, for example, if health resources have to be diverted away from non-Covid care.”The pair added that it may be justifiable for the state to restrict vaccine refusers if it turns out the vaccines reduce onward transmission.They also highlighted that allowing unvaccinated individuals to circulate freely may be associated with the development and spread of mutations of the virus, some of which might become vaccine-resistant.Vaccine passportsIn December it emerged that Los Angeles County plans to let Covid vaccine recipients store proof of immunization in the Apple Wallet on their iPhone, which can also store tickets and boarding passes in digital form. Officials say it will first be used to remind people to get their second shot of the vaccine but it could, eventually, be used to gain access to concert venues or airline flights.”The idea of immunity certificates is not new,” Kevin Trilli, chief product officer at identity verification start-up Onfido, told CNBC. “For instance, children who get vaccinations for measles, polio and other diseases often must show their immunity certificate to register at a new school. Health passports could be a way to help reopen the economy and manage the new normal with a privacy-first approach.” Trilli added: “There is a growing appetite for the use of health passports/certificates within the travel industry to improve the safety of their staff and customers, as well as to instil greater levels of confidence to help re-catalyze the tourism industry.”In May, John Holland-Kaye, CEO of the U.K.’s busiest airport Heathrow, backed the introduction of health certificates to help the country emerge from the more stringent travel restrictions in place at that time. Heathrow Airport did not immediately respond to CNBC’s request for comment.Elsewhere, the CEO of Delta Air Lines, Ed Bastian, said in April that immunity passports could be used to help fliers feel more confident in their personal safety while traveling. A spokesperson for Ryanair said “vaccination won’t be a requirement when flying Ryanair” when CNBC asked if it would ever prevent non-vaccinated people from flying on its aircraft. British Airways, Qantas, and easyJet did not respond to CNBC’s request for comment.The situation in BritainLast year, Nadhim Zahawi, the business minister who was appointed U.K. vaccine tsar at the end of November, said the public may need an immunity passport to access some places. “We are looking at the technology, and of course a way of people being able to inform their GP (doctor) if they have been vaccinated,” said Zahawi on Nov. 30 during an interview with BBC Radio 4. “Restaurants, bars, cinemas and other venues, sports venues, will probably also use that system.”Not everyone likes that idea. Sam Berry, who runs two restaurants in southwest London called Hideaway and No.97, told CNBC: “We are big believers in everyone being treated equally. Everyone is entitled to their view and beliefs and we wouldn’t want to stop that.”He added: “Hospitality would be split with restaurants and bars for vaccinated guests and then bars and restaurants popping up that will cater for non-vaccinated guests. It just sounds crazy to me.”Darren Jones, an opposition Labour lawmaker in Britain, told CNBC: “I just hope that we have a proper debate and full scrutiny of any proposed immunity passports, which I assume will end up being a thing even if they aren’t a thing.”Jones added that any immunity passports should be linked to a “long overdue debate about a proper national ID system.”The Oxford-AstraZeneca vaccine was approved by U.K. regulators on Dec. 30, meaning there are now two safe vaccines available to British citizens.But millions of people across the country still don’t want to be vaccinated, according to opinion polls. Some fear needles, some believe in unsubstantiated conspiracy theories and some are worried about potential side effects. Others just don’t think getting vaccinated is necessary and would rather risk catching Covid. Cabinet Office Minister Michael Gove said on Dec. 1 that there are “no plans” to introduce a vaccine passport and the Department of Health and Social Care reiterated the message when contacted by CNBC.The DHSC said it will be able to gather the evidence to prove the impact on infection rates, hospitalization and reduced deaths as large numbers of people from at-risk groups are given an effective vaccine.If successful, this should in time lead to a substantial reassessment of the current restrictions.