After months of costly shutdowns, closed borders and curtailed personal freedoms, the concept of vaccine passports is gaining traction with governments eager to plot their path through the next phase of the COVID-19 pandemic. A number of countries, including Bahrain and China, have already rolled out their own forms of certification ostensibly intended to ease future international travel or revive activity in hard-hit sectors of economies, such as hospitality. Several others are weighing whether to follow suit and embrace the idea of documentation for those who have been vaccinated against the novel coronavirus. Sceptics, meanwhile, warn a slew of possible wide-ranging adverse effects still needs to be addressed.