A source familiar with the matter told ABC News a cosmetic product was inside the vials of fake vaccine in Poland; Pfizer is now working closely with local authorities.
The Justice Department's International Computer Hacking and Intellectual Property attorneys in Latin America and Eastern Europe are "aware" of the counterfeit Pfizer vaccines identified in Mexico and Poland, and "are seeking to coordinate with and support local authorities and Pfizer, as needed," the DOJ said.
DOJ and the law enforcement agencies at the National Intellectual Property Rights Coordination Center "continue to closely monitor U.S. sources for any indication of fakes in the domestic supply chain," the spokesman said.
This latest volley of fraud was first reported by The Wall Street Journal, however, it's not the first time this issue has been raised on the international stage.
In March, the World Health Organization issued an alert for "falsified" Pfizer vaccines detected in Mexico, which was given to patients outside authorized programs, and that WHO warned at the time "may still be in circulation in the region and may continue to be offered."
U.S. federal authorities have seized at least eight websites for posing as biotech companies offering both coronavirus treatments and vaccines, allegedly in order to harvest people's personal information for "nefarious" use in fraud, phishing attacks and deployment of malware.
Homeland Security Investigations, part of U.S. Immigration and Customs Enforcement, was notified of two of those sites by a victim biotech company that had been granted FDA emergency use authorization for their COVID-19 antibody drug cocktail treatment, the Justice Department said earlier this month. A spokesperson for Regeneron told ABC News its company was the one victimized.
Another domain name offered coronavirus vaccines for sale that it claimed were manufactured by pharmaceutical companies that had been granted EUA, the Justice Department said. Under the site's "shop" tab, there were two counterfeit vaccinations offered that it claimed did not require sub-zero storage. But the domain had been created in February 2021, and its registrar organization was listed as a privacy service used to shield domain registrants' actual information from being seen publicly.
Undercover HSI special agents called the phone number listed on the site in mid-March, and an "unknown individual agreed to sell 50 vials of the counterfeit vaccines for $20 each with a $500 deposit, and the remaining $500 due upon receipt of the vaccine doses," the Justice Department said.
On Wednesday, Pfizer warned the public not to trust online vendors selling the vaccine.
"Patients should never try to secure a vaccine online -- no legitimate vaccine is sold online -- and only get vaccinated at official vaccination centers or by certified healthcare providers," a spokesperson told ABC News. "We continue to work with governments, law enforcement, healthcare providers and others to combat this illegal trade."
ABC News' Anne Laurent contributed to this report.