Even before any Covid-19 vaccines were invented, vaccine passports for participation in public activities appeared likely.
Australia's plagued vaccine rollout meant such requirements lay in a distant future - until now.
Australian political leaders have begun talking about a two-track future.
Proof of vaccination is already required in contexts around the globe by governments and private companies for people seeking to travel, dine and party.
We can expect a similar scenario here. So how will Australians be able to prove they're fully vaccinated?
NSW and Victoria are experiencing high new Covid case numbers. Both states have indicated reaching vaccination targets of 70-80 per cent will be required for widespread easing of restrictions.
They've also suggested some freedoms will be only available to people who are fully vaccinated.
NSW Premier Gladys Berejiklian yesterday announced freedoms for fully vaccinated people once 70% of the state's eligible population are double dosed. These include being able to go to hospitality venues, hairdressers and gyms, and have five people to your home.
Attention is now turning to the ways in which these and other Australian governments will require proof of vaccination for entry into public and private spaces.
Currently, vaccinated Australians can access a Covid-19 digital certificate through MyGov or the Express Plus Medicare app.
Those needing proof of vaccination for overseas travel will soon have this linked to their passport chips, along with a smartphone compatible QR code.
For returned travellers, this technology is likely to inform the circumstances under which they quarantine. Fully vaccinated travellers may have less stringent requirements than those who are unvaccinated, so technology to demonstrate this will be necessary.
States are also preparing to require proof of vaccination for local participation in hospitality venues and events. This would very likely be different to the way you would prove your vaccination status for travelling overseas.
New South Wales is set to trial and then introduce a vaccine passport in October.
Vaccination data from the Australian Immunisation Register would be embedded in the Service NSW app, meeting hospitality industry demands for a simple process.
However, errors in the uploading and registration of data for vaccinated individuals will need resolving to avoid leaving them out in the cold.
Victorian Premier Daniel Andrews has announced the state will pursue its own version of a vaccine passport.
A "vaccinated economy" to be piloted in regional Victoria will allow only the double-dosed to access events, facilities and services. Again, the hospitality industry supports easy-to-use vaccine passports following their role in reopenings overseas.
Currently, the only formal medical exemption in Australia for Covid-19 vaccines is available on a federal government form. Until now, this form has been used for the country's "No Jab" policies.
Recently updated for Covid-19 vaccines, it lists a very narrow set of criteria for exemption and can be lodged only by specific medical practitioners.
All levels of government using vaccine passports will need to consider whether other types of exemptions are appropriate or necessary, including for people who have recently been infected with Covid and are advised not to vaccinate for up to six months.
Victoria's human rights apparatus indicates a wider set of considerations or exemptions may be necessary for those unwilling or unable to vaccinate.
Governments will then need to work out how to manage these exemptions with the technologies they use.
One common way of managing people who are unvaccinated for any reason is to demand proof of a negative Covid-19 test.
Italy's vaccination passport uses this alternative, and France's Pass Sanitaire, or "health pass" has a similar option. Israel's Green Pass system enables temporary passes for the uninfected, good for 72 hours.
Whether or how these negative tests would be integrated into Australian systems remains to be seen. Pending policies for nightclubs in England and Scotland are set to exclude the "negative test" opt out, meaning only the fully vaccinated will be able to access these venues.
Some Australian states and regions will be scrambling for technology if they want to go down the vaccine passport route.
The check-in app used in Queensland, Tasmania, the NT and the ACT lacks verification mechanisms and is not designed to hold a vaccine passport.
Western Australia is focused on vaccine requirements for interstate travellers and health-care workers, and so far has made no moves towards requiring vaccines for local activities; nor has South Australia.
Research suggests there's public support for these kinds of measures in Australia, and there are good reasons to prefer governments introducing the terms of a vaccine mandate rather than private corporations.
However, there are issues of legality, viability and ethics to consider, with venue and individual compliance likely to remain a key issue.
• Katie Attwell is a Senior Lecturer at The University of Western Australia.
• This article is republished from The Conversation under a Creative Commons license. Read the original article.
The 19-year-old disappeared without her wallet or mobile phone.