Covid vaccines did not cause a 300% rise in cancer and miscarriage rates

A widely shared post on Facebook falsely claims that Covid vaccines caused a tripling of miscarriage and cancer rates, and a tenfold rise in neurological disorders.

In fact, these numbers were based on the result of a data error in military records from the US Department of Defense (DoD), which was corrected more than three years ago.

The real rises were much smaller—and the evidence doesn’t tell us they were caused by the Covid vaccines anyway.

The post features a video of a man called Thomas Renz citing data that he says comes from the Defense Medical Database (DMED) during a panel discussion [4:55:05] about the Covid-19 response, hosted by the US Senator Ron Johnson in January 2022. This is how we know that the “jabs” referred to in the Facebook post relate to Covid.

Mr Renz says in the video: “We have substantial data showing that we saw, for example, miscarriages increased by 300% over the five-year average, almost. We saw almost a 300% increase in cancer over the five-year average… Neurological issues, which would affect our pilots, over a 1,000% increase.”

In fact, these numbers are based on a data error. A spokesperson for the Defense Health Agency’s Armed Forces Surveillance Division told Politifact, another fact checker, in 2022 that they came from a comparison with faulty data from the past, which made the rate of these and other conditions in 2016-2020 seem much too low. So when the more complete 2021 data was compared against that faulty baseline, it created the false impression of dramatic spikes in various conditions.

Senator Johnson himself later acknowledged receipt of a document from the DoD, which explained that the error happened during a server migration. As the document said: “The data for years 2016 through 2020 contained only approximately 10% of the true number of outpatient medical encounters for that period, which created an inaccurate appearance that diagnoses for medical conditions increased when compared to previous years.”

While the document doesn’t give a figure for the correct rise in miscarriage or cancer encounter rates in general, it says the correct figure for neurological issues was 3%, and cites a number of increases for specific cancers that are well below 300%. The number of testicular cancer encounters rose 3%, for example, not 369%. For breast cancer, it was 1.1% instead of 487%.

This has nothing to do with Covid vaccines anyway

It’s worth saying that even after the error was corrected, this data can’t be used to calculate the change in the rates of these conditions—let alone any changes caused by the Covid vaccines.

The data measures the number of “outpatient medical encounters” for active service members, meaning the number of times they had contact with medical staff for given conditions. There might be more than one encounter per condition, and the encounters recorded in a given year might relate to a condition that developed much earlier.

As the DoD notes in its document, “Counts of health care encounters are not representative of new cases of these diagnoses; they are a measure of the workload for the health system regarding provision of care associated with these diagnoses. Counts of health care encounters cannot be used as a proxy for the prevalence of disease.”

In short: “The ability to make inferences from the data using the available preset queries is very limited… To address specific questions on Service members’ health, a more thorough analysis is required.”

Besides, even if this data did show a change in prevalence, it still wouldn’t tell us that the change was caused by the Covid vaccines. Some people may have had these conditions before being vaccinated, while others may have developed them for other reasons.

We, and other fact checkers, have written about this error when it has been the source of misinformation several times before.

Serious side effects from Covid vaccination do occur on rare occasions. But the MHRA, which monitors their safety in the UK, says: “The benefits of the vaccines in preventing COVID-19 and serious complications associated with COVID-19 far outweigh any currently known side effects in the majority of patients.”

Office for National Statistics data shows that, in England, 63 deaths involving Covid vaccines were registered up to July 2023. But analysis from the UK Health Security Agency found that the vaccines prevented 127,500 deaths in England up to 24 September 2021. Overall, it is estimated that they save millions of lives worldwide.

Bad information can be dangerous if people use it to make decisions about their health.

Full Fact has approached the author of this post, Mr Renz and Senator Johnson for comment.