Fact Check-SM-102 lipid in Moderna COVID-19 vaccine is not harmful

The safety fact sheet that social media users are sharing as alleged proof of the harmful nature of the lipid SM-102 in the Moderna COVID-19 vaccine, is actually describing the dangers of chloroform. The fact sheet is for SM-102 supplied by biotechnology company Cayman Chemical as a solution in chloroform, meaning it is made up of 90% chloroform and 10% SM-102, where chloroform is listed as the only dangerous component.

The posts (here , here , here , here) display a video or screenshots indicating that SM-102 is an ingredient in the Moderna COVID-19 vaccine, followed by a Cayman Chemical ( product information page for “SM-102”, visible here , and the safety fact sheet for that product, seen here . Users highlight that these pages say the product is “not for human or veterinary use”, “flammable”, “fatal in contact with skin”, “suspected of causing cancer” and more.

SM-102 is a lipid excipient, meaning it is a substance that is not soluble in water that is used as an inactive ingredient in a vaccine (here , here).

SM-102 is listed as one of the lipids in the Moderna COVID-19 vaccine as seen in the U.S. Food and Drug Administration (FDA) fact sheet here . Moderna describes SM-102 here as a “proprietary ionizable lipid” meaning it was produced for use in vaccines by Moderna. This lipid is not in the other COVID-19 vaccines granted an Emergency Use Authorization (EUA) by the FDA, as seen in the Pfizer and Janssen fact sheets here and here .

However, the Cayman Chemical product information sheet explains here that they supply SM-102 as “a solution in chloroform”. The Cayman Chemical safety fact sheet which lists the hazards explains here that the product (labelled “item No. 33474”) is therefore made up of 90% chloroform and 10% SM-102. The only product listed as a “dangerous component” and “hazard-determining component of labelling” (here , here) is chloroform. SM-102 is simply listed under “other ingredients”.

A Cayman Chemical statement here confirms that Cayman’s SM-102 is a mixture of 90% chloroform and 10% SM-102 intended for research use by academic and industrial scientists in the preclinical exploration of novel therapies. It goes on to explain that SM-102 is not harmful: “Neither the National Institute for Occupational Safety and Health (NIOSH), Registry of Toxic Effects of Chemical Substances (RTECS), or the European Chemicals Agency (ECHA) Classification and Labelling Inventory list any hazards associated with SM-102.”

The product description clearly states that Cayman Chemical’s SM-102 (Item No. 33474) is “not for human or veterinary use”.

Chloroform is not listed as one of the Moderna COVID-19’s vaccine ingredients (here).

A full list of excipients present in the Moderna COVID-19 vaccine, seen here , which does not include chloroform.

Dr Rongjun Chen, Reader in Biomaterials Engineering, Department of Chemical Engineering, Imperial College London (here), told Reuters via email, through the Science Media Center (, “SM-102 present in Moderna’s mRNA vaccines is for human use, and thus different from Cayman’s SM-102 (No. 33474).”

“Chloroform is a volatile, chlorinated solvent. It does have known serious hazards and is believed to be carcinogenic and hepatoxic. However, chloroform is not shown on the list of ingredients in Moderna’s mRNA vaccines,” Chen added.

The Moderna vaccine uses messenger RNA (mRNA), which gives instructions to our cells to make a protein called a spike protein, found on the surface of the virus that causes COVID-19. Our immune system recognizes that the protein doesn’t belong there and starts to make antibodies, building an immune response (here , here).

The lipid SM-102 is used in the Moderna vaccines to make lipid nanoparticles, which protect the mRNA when the vaccine is injected and transport it to the right place in cells (here , here).

The FDA reviewed safety data from 30,351 participants aged 18 and over in the Moderna vaccine trials and did not identify any specific safety concerns that would prevent them from issuing the EUA (here).

Moderna did not immediately respond to Reuters’ request for comment.

Reuters has previously debunked other false claims about lipid nanoparticles in COVID-19 vaccines here .


Partly false. SM-102 is a lipid used in the Moderna COVID-19 vaccine but the Cayman Chemical safety fact sheet in the posts shows the hazards of chloroform not SM-102.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work here .