False online claims have suggested an unfounded link between COVID-19 vaccines and HIV, the virus that causes AIDs.
The misleading posts claim that coronavirus jabs are creating new variants of the unrelated virus to emerge.
The misinformation has spread amid greater global awareness for HIV testing in countries such as the United Kingdom and the United States.
No clinical evidence has shown any link between COVID-19 vaccines and AIDs and global health authorities have dismissed the claims.
The World Health Organization (WHO) has reiterated that coronavirus vaccines are safe and effective and that any risks are extremely rare.
But anti-vaccine demonstrations are still being held in several cities, including the so-called "Freedom Convoy" truckers' protest in Canada.
Other protesters in the United Kingdom have cited ancient, defunct laws in an attempt to shut down the country's vaccination programme.
Many online users have falsely claimed that COVID-19 vaccines are creating a new disease, so-called "vaccine acquired immunodeficiency syndrome" or "VAIDS".
Posts referencing the term have widely circulated on Facebook, Twitter, and Reddit, while Google search terms for “VAIDS” have also risen in recent days.
"Do NOT take the vaccine #Vaids," one user wrote on Facebook, while others kept their posts vague, asking, “What is VAIDS?”
Neither the WHO nor the European Centre for Disease Prevention and Control (ECDC) has documented any such disease known as "VAIDS".
A WHO spokesperson told Euronews that no "reputable source" has published the claims about "VAIDS" and labelled the reports as "misinformation".
Other online users have falsely suggested a link between COVID-19 vaccines and the new HIV variant recently discovered in the Netherlands.
However, the VB variant of HIV is not itself new and is believed to have originated long before coronavirus vaccines existed.
"Researchers estimate that the VB variant first arose during the late 1980s and 1990s in the Netherlands," said Oxford University, which discovered the highly virulent strain.
"It spread more quickly than other HIV variants during the 2000s, but its spread has been declining since around 2010."
Oxford University said the research "emphasises the importance" of HIV testing and also reiterated that the public should not be worried about the VB variant.
Misinformation about COVID-19 vaccines and HIV/AIDS has been circulating for several months and has even been spread by elected officials.
Brazilian President Jair Bolsonaro was sanctioned by social media companies in October after falsely claiming that UK citizens were developing AIDS faster than expected after receiving two coronavirus vaccines doses.
The Brazilian Society of Infectious Diseases states that there is "no known relationship" between any coronavirus vaccines and AIDS.
Fact-checkers have regularly debunked false rumours that COVID jabs reduce a human's immense system and make it more susceptible to other diseases.
“AIDS is a generalised body-wide compromise of a specific subset of immune cells (mostly CD4+ lymphocytes) caused specifically by infection with the HIV-1 virus,” said Dr Grant McFadden, director of the Biodesign Center for Immunotherapy, Vaccines and Virotherapy at Arizona State University.
“There is no vaccine-induced counterpart of AIDS,” he told The Associated Press.
Given that billions of people around the world have already been vaccinated against COVID-19, McFadden said, “if such a thing as VAIDS existed, we would have detected it by now.”