When Korea's public health policymakers tightened vaccine pass regulations, further restricting the types of public establishments that the unvaccinated could visit, they probably didn't anticipate one unintended consequence: the emergence of an online black market for vaccine passes and other immunization documents.

As one restaurant worker from Songpa District in southern Seoul, who requested to be named only by his surname Kim, discovered upon scanning an immunization card handed to him by a guy who came into the restaurant to dine, he expressed his surprise.

"When he presented me the vaccination pass, it was registered under a woman's name," Kim recounted. In response to his questioning the individual for identification that matched the immunization pass, the man admitted he had not been vaccinated after all.

"Now that I've realized I have to personally verify each customer's vaccination status, I have much more work to do," Kim lamented, laughing exasperatedly.

The Covid-19 pandemic has been ongoing for more than two years, and despite stricter restrictions on unvaccinated people's access to public places and dire warnings from public health authorities about the country's mounting daily caseload and acute shortage of intensive care units, those who have refused to be immunized without a legitimate medical reason are failing to enforce anti-disease measures.

It has become common practice to purposefully circumvent vaccination pass rules in a variety of ways. One approach used by the unvaccinated to get around vaccination pass requirements is to use a Naver ID that belongs to a vaccinated individual to bypass the limits.

People's vaccination status may also be determined via their Naver IDs, which are linked to phone numbers entered at vaccination clinics by them when they obtain their inoculations. Unvaccinated persons, on the other hand, may simply circumvent the system by purchasing the Naver log-in information of a vaccinated person and using them as their own vaccine pass, which is legal in Korea.

The secondhand shopping application Danggeun Market has seen an increase in the number of advertisements in recent weeks offering to acquire Naver log-in data belonging to people who have received vaccinations. One such post stated that the author would be prepared to give 50,000 won ($42) for the Naver ID of a person who has received vaccinations.

On other online forums, some people offered advice on how to fudge a negative result on a polymerase chain reaction (PCR) test, which is the normal process for screening an individual for a Covid-19 infection and may be used in place of a regular vaccine pass for a limited period of time.

As one user pointed out, "you can simply copy and paste this message displaying a negative result on the PCR test and replace the name in the text with your own," which was a routine test result notice issued to testers' phones by screening clinics.

Invariably, individuals working in companies that need consumers to provide a vaccination pass for access have the burden of verifying the legitimacy of the vaccine passes they receive, resulting in complaints from both company owners and their employees.

It's nearly hard to tell whether a vaccination pass belongs to a client during lunch and evening hours, when it's practically impossible to ensure that all consumers scan their passes, according to one restaurant employee in the city of Seongnam, Gyeonggi.

"When clients show me their vaccination cards, I have no option but to accept that it is in fact theirs," said a part-time café employee in central Seoul's Yongsan District.

Customers presenting other people's immunization passes as their own, according to posts on internet discussion networks for small business owners, are becoming increasingly aware of — and frustrated with — the practice.

In the words of one critic, "all company owners should be on the lookout for unvaccinated adolescents in their early twenties who are stealing vaccination passes from other individuals." "It's almost as if we had to perform our own crime scene investigation," said another cynically.

Businesses that do manage to attract clients, on the other hand, may find themselves the target of online retaliation from unvaccinated individuals who were turned away at the door.

According to one Instagram account, establishments that turned individuals away because they did not have a vaccination pass are listed, and its 5,500 followers are advised to avoid such locations "so they do not end up going there and being denied access." Around 100 eateries and cafés around the country have been included in the account.

On Friday, a new Naver community page was launched with the heading "Businesses that discriminate against unvaccinated persons." The page also includes a list of "good firms" that, according to the page, do not undertake rigorous vaccination pass screenings on their customers.

Owners of most such establishments, on the other hand, said that they had never admitted clients who couldn't show proof of immunization status.

'I've only ever refused access to two guys, one of whom was unvaccinated,' said a restaurant owner in Uijeongbu, Gyeonggi province, who identified himself as Lee and who owns a company that was among those identified as having insufficient inspection methods. "It makes me really unhappy that someone would write anything like this."