We've Moved

Visit our new website at Science.Feedback.org for scientific verifications of viral claims.

Alleged spikes in medical conditions among the military after COVID-19 vaccine rollout are based on faulty data due to a database glitch

In 2021, cases of pregnancy and fertility issues, cancer, neurological issues, and heart disease spiked after COVID-19 vaccination
Inaccurate: Due to an error, the Defense Medical Epidemiology Database greatly underreported the number of medical conditions between 2016 and 2020. Claims that several medical conditions among the military greatly increased after COVID-19 vaccination were therefore based on erroneous data and are incorrect.
Unsupported: Data from safety monitoring and multiple studies don’t support the claim that COVID-19 vaccines have caused a significant increase in the incidence of medical conditions.
COVID-19 vaccines are proven to be very safe and effective at preventing COVID-19 hospitalizations and deaths. Although certain COVID-19 vaccines are associated with a slightly increased risk of blood clotting or heart inflammation, COVID-19 itself is associated with a higher rate of these and other conditions. Overall, scientific evidence indicates that the benefits of vaccines largely outweigh their risks.

FULL CLAIM: In 2021, cases of pregnancy and fertility issues, cancer, neurological issues, and heart disease spiked after COVID-19 vaccination


As of 15 February 2022, more than 4.8 billion people—almost 62% of the global population— have received at least one dose of a COVID-19 vaccine. Safety monitoring data clearly show that the benefits of COVID-19 vaccines outweigh their risks. Yet, claims that call into question the vaccines’ safety continue to circulate on social media.

One example is a meme published on Facebook on 13 February 2022, claiming an alleged “spike” in infertility and pregnancy issues, cancer, neurological issues, and heart disease. Exactly what the figures in the meme related to was left unsaid, but the same figures can also be seen in this Instagram post equating COVID-19 vaccination with genocide. Taken together, the message sent by these posts is that COVID-19 vaccines are the cause of this alleged spike in health problems. Combined, posts sharing the same figures received more than 5,000 interactions on Facebook and Instagram, according to the social media analytics tool CrowdTangle.

One Instagram meme attributed the claim to attorney Thomas Renz, who presented the exact figures during a COVID-19 panel discussion hosted by U.S. Senator Ron Johnson on 24 January 2022. Citing data from the Defense Medical Epidemiology Database (DMED), Renz claimed that a long list of medical conditions skyrocketed among the military personnel in 2021, after COVID-19 vaccination, compared to the previous five-year average.

According to Renz, the data were provided by military physicians Theresa Long, Peter Chambers, and Samuel Sigoloff, whom he represented. Long made false claims about COVID-19 vaccines in the past, including that they contain “the active ingredient in antifreeze“, as part of a lawsuit against the Pentagon to stop its vaccine mandates. The lawsuit was filed by America’s Frontline Doctors, an organization known for spreading misinformation about COVID-19 vaccines and promoting unproven COVID-19 treatments, with which Renz also has connections.

However, the data used to make these comparisons are wrong, making Renz’s figures inaccurate, as we will explain below. In addition, data from safety monitoring and scientific studies show no evidence of an increase in these conditions, contradicting Renz’s claim.

The alleged increases in medical problems among the military in 2021 were due to an error in the database

The DMED is a database that provides remote access to a subset of data on diseases and medical events contained within the Defense Medical Surveillance System (DMSS). When comparing DMED data with the data source on the DMSS, officials found that there was an error in the number of medical diagnoses from the previous five years.

Peter Graves, spokesperson for the Defense Health Agency’s Armed Forces Surveillance Division, explained to the fact-checking organization PolitiFact that “the data was incorrect for the years 2016-2020″ due to an error in the database that led to a large underreporting of conditions for that period. In other words, the figures that established a baseline for the incidence of these medical conditions were much lower than they actually were.

In contrast, the figures for 2021 were correct, giving the “appearance of significant increased occurrence of all medical diagnoses in 2021 because of the underreported data for 2016-2020”. Graves said that the database was later taken down to “identify and correct the root-cause of the data corruption”.

Besides being inaccurate, a closer look at the figures provided by Renz show that such huge increases are implausible and inconsistent with the current scientific evidence.

No evidence that COVID-19 vaccines increase cancer risk

The figures presented by Renz and shared on social media claimed significant increases in the incidence of several types of cancer, including breast cancer (487%), testicular cancer (369%), and malignant neoplasms (664%).

As Health Feedback explained in an earlier review, there is no scientific evidence suggesting that the COVID-19 vaccines increase the risk of cancer. Furthermore, such a large increase would have been observed worldwide. However, public health authorities and cancer associations haven’t reported a sudden surge in cancer cases since the beginning of the COVID-19 vaccination campaign.

David Gorski, a professor of surgical oncology at Wayne State University and an editor at Science-Based Medicine, pointed out on his blog that the cancer numbers alone already indicate a problem in the data. First, cancer rates “never show incredibly rapid and dramatic changes” and “such an increase can only be accounted for by reporting issues”.

Second, cancer is a process that generally takes years to develop following exposure to a carcinogen. Even if the increase were real, it would be biologically implausible to attribute it to the COVID-19 vaccines administered less than a year before. Gorski explained:

“To believe that COVID-19 vaccines were responsible for this increase in cancer incidence among military personnel, one would be obligated to believe that COVID-19 vaccines are far more carcinogenic than ionizing radiation from atomic bombs.”

In short, while the cancer statistics for 2021 aren’t yet available, such a dramatic increase in cancer rates hasn’t been observed in the general population. This is unusual if the vaccines are as carcinogenic as Renz and the others claimed. Therefore, the foremost explanation for the apparently massive and sudden rise in cancer in the military, that is also consistent with the current evidence and the known mechanism of cancer, is an error in the data.

COVID-19 vaccines don’t pose a risk to pregnancy and fertility, but the disease might

The meme alleged increases in miscarriages (279%), birth defects (155%), ovarian dysfunction (437%), and infertility in men (350%) and women (471%). However, these figures contradict current evidence from clinical research and safety monitoring, which doesn’t suggest that COVID-19 vaccines negatively impact fertility or pregnancy, as Health Feedback explained in this review.

In contrast, pregnant women are at a higher risk of severe COVID-19 compared to non-pregnant women, particularly in the second and third trimesters. This in turn increases the risk of preterm birth and stillbirth.

Initial COVID-19 vaccine trials didn’t include pregnant women, leading to a lack of clinical data for this group in the early stages of the vaccination campaign. In April 2021, the U.S. Centers for Disease Control and Prevention (CDC) began recommending vaccines for expectant mothers, after preliminary research found no obvious safety issues[1]. Later studies involving thousands of pregnancies showed no sign of an increased risk of miscarriages[2-4], preterm births[5] or other safety concerns for the mothers or the babies following COVID-19 vaccination[6].

Research also found that COVID-19 vaccines had no impact on fertility, in both men and women. Two different research groups in the U.S. showed that vaccination didn’t affect sperm quality or embryo implantation[7,8].

In contrast, Ranjith Ramasamy, a urologist at the University of Miami and an author of the study on sperm quality, explained in an article for The Conversation that SARS-CoV-2 infection of testes tissue could lead to erectile dysfunction and male infertility. In fact, another study evaluating the chances of conception in more than 2,000 couples found that SARS-CoV-2 infection in the male partner slightly decreased the likelihood of conception, probably due to a temporary reduction in male fertility after the disease[9]. Conversely, vaccination of either partner made no difference to the chances of conception.

Neurological issues are much more likely after infection than after COVID-19 vaccination

The meme also alleged an increase of 1,048% in neurological issues, including Guillain-Barré syndrome (551%), Bell’s palsy (291%), and multiple sclerosis (680%).

Adenoviral vector vaccines (Johnson & Johnson and Oxford-AstraZeneca) have been associated with a small increased risk of some neurological conditions, including Guillain–Barré syndrome and Bell’s palsy. Such cases are very infrequent[10], and most people who are treated fully recover[11].

Also, it is important to note that COVID-19 itself is more likely to cause these neurological conditions than the COVID-19 vaccines. A study from the Universities of Oxford and Edinburgh evaluated the rate of neurological adverse events following COVID-19 vaccination and SARS-CoV-2 infection using records of 32 million adults from the U.K. National Health Service[10]. The results, published in Nature Medicine, showed an increased risk of Guillain-Barré syndrome and Bell’s palsy after vaccination with the Oxford-AstraZeneca vaccine and an increased risk of hemorrhagic stroke after vaccination with the Pfizer-BioNTech vaccine.

However, the overall risk was still minimal. When compared to the baseline risk of developing Guillain-Barré syndrome, researchers observed 145 more cases per 10 million people among those who were infected, as compared to 38 more cases per 10 million people among those who were vaccinated, more than a four-fold difference.

The results from these studies demonstrate that even though certain COVID-19 vaccines are associated with an increased risk of certain neurological problems, such problems are more likely to occur following SARS-CoV-2 infection. This means that the benefits of vaccination outweigh the risks. The benefit is even higher when we go beyond just Guillain-Barré syndrome and consider the other risks associated with COVID-19, including long-term effects and even death.

Heart problems are also more common after infection than after vaccination

The meme claimed increases in hypertension (2,181%), pulmonary embolism (468%), tachycardia (302%), and myocardial infarction (269%).

The Johnson & Johnson and Oxford-AstraZeneca COVID-19 vaccines have been linked to very rare cases of a blood clotting disorder called thrombosis with thrombocytopenia syndrome. To minimize this risk, many countries like the U.K. recommend mRNA COVID-19 vaccines for individuals under 40, who are at higher risk of this rare adverse event.

On the other hand, the mRNA COVID-19 vaccines from Moderna, and Pfizer and BioNTech have been associated with a slightly increased risk of heart inflammation (myocarditis and pericarditis), particularly in young male individuals. However, the benefits of vaccination outweigh this small potential risk.

It’s important to keep in mind that viral infections, including COVID-19, can also cause heart inflammation. Estimates indicate that the risk of heart inflammation and cardiac complications is about five times higher after COVID-19 than after vaccination[12]. Furthermore, cases of heart inflammation following vaccination are generally milder and have better clinical outcomes than those caused by infections, as Health Feedback explained in an earlier review.


The figures shown by Renz and others linking COVID-19 vaccines with an increase in medical conditions such as cancer, pregnancy and fertility issues, neurological conditions, and heart problems among the military personnel are based on incorrect data due to an error in the databases.

There is no evidence whatsoever suggesting that COVID-19 vaccines increase the risk of cancer or the likelihood of pregnancy complications. While vaccination has been associated with a slight increase in the risk of Guillain-Barré syndrome and rare cases of blood clotting and heart inflammation, such cases are infrequent and less likely to occur following vaccination than due to COVID-19 itself.

COVID-19 vaccines have proven to be very safe and effective. Data from clinical trials and safety monitoring indicate that the benefits of COVID-19 vaccines in preventing COVID-19 and its associated risks outweigh the known and potential risks. For this reason, public health authorities like the CDC recommend that “everyone ages five years and older get a COVID-19 vaccine”.



Published on: 17 Feb 2022 | Editor:

Health Feedback is a non-partisan, non-profit organization dedicated to science education. Our reviews are crowdsourced directly from a community of scientists with relevant expertise. We strive to explain whether and why information is or is not consistent with the science and to help readers know which news to trust.
Please get in touch if you have any comment or think there is an important claim or article that would need to be reviewed.