DMSC debunks SV40 contamination claim about mRNA vaccines
Thailand’s Department of Medical Sciences says online claims that mRNA vaccines contain SV40 and raise cancer risk are false, citing the modern manufacturing process and strict quality controls.
The Department of Medical Sciences (DMSC) under the Ministry of Public Health has confirmed that online claims that mRNA vaccines are contaminated with SV40 and increase cancer in humans are false, adding that there is still no clear evidence that SV40 leads to a higher incidence of cancer in humans.
The Anti-Fake News Center Thailand (AFNCT) under the Ministry of Digital Economy and Society (DES) said it checked the claim with the DMSC, which confirmed it was untrue.
According to the DMSC, SV40 (Simian Virus 40) is a small, non-enveloped virus in the Polyomaviridae family with a double-stranded DNA genome. It was discovered in 1960 in monkey kidney cells used to produce polio vaccines at the time. While SV40 was later found to induce tumours in some experimental animals, follow-up data on people who received polio vaccines during that period have not found clear evidence that SV40 increases cancer in humans.
The DMSC said today’s mRNA vaccine manufacturing process is entirely different, relying on in vitro synthesis and not using monkey cells as a production source—eliminating the possibility of SV40 contamination at the outset.
It added that each vaccine batch undergoes purification and stringent quality checks using advanced technology to keep residual substances at extremely low levels in line with international standards.
