Fact Check-No evidence COVID-19 vaccines will cause ‘cytokine storms’  

A viral Facebook post has repeated misinformation that people vaccinated against COVID-19 will suffer from overactive immune responses called cytokine storms. There is no evidence to support this.

The uploaded screenshot reads: “When the vaccinated meet the wild virus in nature, after two shots and a year later, their bodies will have a cytokines [sic] storm and then we will have countless deaths. Government and MSM will say ‘oh it’s another CoVid [sic] variant’. Just. Wait. And. See.” (here)

This post repeats a common falsehood that vaccinated individuals will suffer from future health problems or have a shortened lifespan, which is shared without evidence (here , here). However, COVID-19 is a disease proven to kill ( and can have debilitating health impacts (here).   

There is no single definition of a cytokine storm, but a doctor who experienced the illness has described it as an immune response in which the body attacks itself (here).

Experts at the Meedan Health Desk said this happens when outside pathogens (organisms that cause disease, like a virus) trigger an overproduction of proteins called cytokines, leading to lung damage or death (here).

Some studies have connected cytokine storms with severe cases of COVID-19 (here , here and here), although others questioned the link (here , here and here). More importantly, there is no evidence they would result from COVID-19 vaccines.

Neither Moderna, Pfizer-BioNTech nor Oxford-AstraZeneca found any evidence of cytokine storms in their clinical trials (here , here and here) and the UK government has not published any reports of the syndrome in its summary of vaccine adverse reactions (here).

The false claim may stem from reports of cytokine storms that resulted in rare cases from the 2016 Dengue vaccine. However, the Meedan Health Desk emphasises that COVID-19 vaccines have passed Phase 3 clinical trials designed specifically to detect such negative side effects (here).   

The misinformation might also relate to a 2012 study that warned mRNA vaccines could raise cytokine levels in mice, but a professor involved in the report assured Reuters in a previous fact-check that today’s COVID-19 mRNA vaccines are “very different” to those used nine years ago (here).


False. There is no evidence that COVID-19 vaccines cause a dangerous immune response known as a cytokine storm.  

Read more about our work to fact-check social media posts here .