Fact Check-There is no evidence mRNA vaccines reduce life expectancy or cause severe health issues including infertility and neuro-cognitive problems 

Thousands of Facebook users have shared a video making bogus claims about the side effects of mRNA vaccines against COVID-19 like the Pfizer/BioNtech and Moderna jabs. These allegations are baseless and contradict evidence showing that the injections are safe.  

The clip features a woman called Professor Dolores Cahill (, who has repeatedly spread misinformation about COVID-19 (here , here , here and here). She says: “Anyone who’s over 70 who gets one of these mRNA vaccines will probably sadly die within about two to three years.   

“And I would say anyone who gets the mRNA injection, no matter what age you are, your life expectancy will be reduced to, you know, die if you’re in your thirties within five to ten years, and you probably will have allergy, neuro-cognitive issues, inflammation, and of course infertility is the major one” (here).  

Reuters contacted Cahill for comment but received no reply before publication.  


Scientists at the Meedan Health Desk (here) saw the video and responded: “Research shows that mRNA vaccines are safe and effective. Nonetheless, false and misleading online claims are sowing confusion about mRNA side effects. COVID-19 mRNA vaccines have not caused any deaths in clinical trials, and there is no theoretical reason to believe that mRNA vaccines would cause deaths or severe harm to people.” (here)   

Meedan suggested the misinformation may stem from a UK government report, published in late March, that modelled the easing of lockdown restrictions. One paragraph stated: “The resurgence in both hospitalisations and deaths is dominated by those that have received two doses of the vaccine, comprising around 60% and 70% of the wave respectively” (here , page 10).   

However, this does not indicate that COVID-19 mRNA vaccines are ineffective or put someone at higher risk of death. Firstly, the report is based on projection modelling for when lockdown eases, rather than reporting existing data. Secondly, it is predicting deaths among older, vaccinated individuals because they had the highest jab uptake and the biggest health risk. The report clarifies: “This (modelling) is not the result of vaccines being ineffective, merely uptake being so high” (page 18).   

The Meedan scientists added that false claims about mRNA mortality risks may also be connected to adverse events reported after immunisation, through the Yellow Card scheme in the UK and the Vaccine Adverse Event Reporting System (VAERS) in the U.S. However, these programmes do not determine if a jab caused the reported events and sometimes contain errors.   

Cahill’s baseless allegations could also be linked with misinformation that COVID-19 mRNA vaccines cause lethal cytokine storms, an overproduction of proteins called cytokines that can lead to respiratory problems and death. Reuters has debunked this claim here .   


There is also no evidence to suggest COVID-19 mRNA vaccines cause neurocognitive issues, a general term that means a person is experiencing decreased mental function due to a disease other than psychiatric illness (   

The Meedan scientists noted that a neurological illness called functional neurological disorder can result from getting vaccinated but is triggered by “physical and emotionally charged events,” like the process of being vaccinated, rather than the vaccine itself (here).   


Common side effects of mRNA vaccines include pain, redness, and swelling, but research from clinical trials of the Moderna and Pfizer/BioNTech vaccines has not linked the shots with any long-term inflammation or swelling.   

One of the first studies to look at the impact of mRNA COVID-19 jabs on people with pre-existing chronic inflammatory diseases, such as rheumatoid arthritis and inflammatory bowel disease, found patients responded well with relatively minimal side effects (here).   

Experts at Meedan acknowledged some case reports of rheumatoid arthritis flare-ups following Moderna and Pfizer-BioNTech COVID-19 vaccinations but said there is not enough evidence to say immunisation is the cause. They added: “There is no existing evidence or theoretical reason to suggest that inflammation from mRNA COVID-19 vaccines is a concern.”  


There is no evidence to suggest COVID-19 vaccines increase the risk of miscarriage, as explained by Reuters here . According to scientists at Meedan, a key origin of this myth was a 2021 letter sent to the European Medicines Agency by two European anti-vaccination propagandists who falsely claimed the “vaccine contains a spike protein called syncytin-1 [that is] vital for the human placenta in women.” ( 

Syncytin-1 is a vital protein for the human placenta, and destroying this protein would disrupt its formation, which could lead to infertility or miscarriage. However, the COVID-19 mRNA vaccines do not contain syncytin-1, nor do they instruct the body to generate antibodies for the protein.   

The experts added that, while fertility was not studied in vaccine clinical trials, no decrease in fertility has been reported among trial participants, in animal studies or among the millions who have received the mRNA vaccines in the real world.  

“What can lead to adverse pregnancy outcomes is COVID-19: evidence shows that infection earlier in pregnancy increases the risk of complications, ranging from increased need for ventilation to foetal death”, they said (here).   


False. There is no evidence that mRNA vaccines against COVID-19 cause severe harm or early death. 

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