“Covid vaccines caused a tripling of miscarriage and cancer rates and a tenfold rise in neurological conditions.”

• The claim traces to January 2022 testimony organized by attorney Thomas Renz, who presented Defense Medical Epidemiology Database (DMED) queries allegedly showing ~300% increases in miscarriages and cancer diagnoses and roughly 1,000% increases in neurological diagnoses among U.S. service members in 2021 versus the 2016-2020 average — the only quasi-'data' basis ever offered for the specific 3x/3x/10x figures.
• Passive reporting systems (VAERS, Yellow Card, EudraVigilance) contain large numbers of reports of miscarriage, cancer and neurological events following COVID-19 vaccination; these raw reports are unverified and uncontrolled, but are frequently cited as support for the claim.
• Some genuine, rare neurological and cardiac adverse events are established: Guillain-Barré syndrome after adenovirus-vector vaccines (Janssen/AstraZeneca) and myocarditis/pericarditis after mRNA vaccines in young males. Large multinational surveillance (Global Vaccine Data Network, 99 million people) also found small observed-to-expected increases for GBS, cerebral venous sinus thrombosis and ADEM after specific vector vaccines — real signals, though orders of magnitude below a 'tenfold rise' in neurological conditions overall.
• Rates of miscarriage and cancer are genuinely difficult to measure in real time, and diagnosis/reporting of many conditions did shift after 2020 because of pandemic-era disruption in screening and care — a confounder that claim proponents invoke.

• The DMED figures were an artifact of a database error, not a vaccine effect: the Defense Health Agency stated that 2016-2020 records in DMED had been under-reported due to a data corruption/transfer problem, so the 2021 'spike' was an illusion created by an artificially low baseline. After the data were corrected and reloaded, the apparent increases disappeared. This was acknowledged by the DoD in February 2022 and reported by multiple fact-checkers and outlets.
• Miscarriage: prospective and registry studies find no increase. The NEJM v-safe pregnancy registry analysis (Shimabukuro et al., 2021) found spontaneous abortion rates within the expected 10-26% background range; a Norwegian registry study (Magnus et al., NEJM 2021) found no association between vaccination and first-trimester miscarriage (adjusted OR ~0.9-1.0); case-control work in the U.S. Vaccine Safety Datalink reached the same conclusion. No study anywhere reports a tripling.
• Cancer: there is no established biological mechanism by which mRNA or vector COVID vaccines cause cancer, and national cancer registries (e.g., U.S. SEER/NCI, UK, Nordic registries) show no tripling of incidence after 2021. Cancer incidence changed by single-digit percentages, with a dip in 2020 from missed screening followed by catch-up diagnoses — the opposite pattern from a vaccine-caused epidemic. A tripling of cancer would be one of the largest public-health events in history and impossible to hide in registry or mortality data.
• Neurological: large cohort and self-controlled studies covering tens of millions of people found either no increase or small absolute increases for specific rare conditions (e.g., GBS excess of roughly 1-4 cases per million doses of adenovirus-vector vaccine). Population-level neurological disease incidence did not rise tenfold anywhere. mRNA vaccines have generally not shown a GBS signal.
• The claim aggregates three separate outcomes with a single causal explanation and no cited dataset, no denominator, and no comparison group — the hallmark of an ecological/temporal-correlation error. All-cause mortality and disability trends in highly vaccinated countries are inconsistent with harms of the magnitude alleged.
• Independent fact-checks (Reuters, AP, PolitiFact, FactCheck.org, Full Fact) reviewed the DMED claim in 2022 and rated it false or unsupported; the claim has continued to recirculate essentially unchanged, including in 'turbo cancer' variants that have also been examined and found unsupported.

95/100 — the lab’s own confidence in the score above, not a second reading of the claim.

New England Journal of Medicine (Shimabukuro et al., CDC v-safe pregnancy registry)journal · 93 · New England Journal of Medicine (Magnus et al., Norwegian Institute of Public Health) — Covid-19 vaccination and first-trimester miscarriagejournal · 93 · Vaccine / Global Vaccine Data Network — adverse events of special interest in 99 million vaccinated peoplejournal · 90 · U.S. National Cancer Institute, SEER Cancer Stat Facts (all cancer sites incidence trends)gov · 95 · VAERS (CDC/FDA) — data and disclaimer on interpreting passive reportsgov · 88 · U.S. Centers for Disease Control and Prevention — COVID-19 vaccination in pregnancygov · 88

• VAERS and other passive adverse-event systems contain reports of miscarriages, cancers and neurological problems after COVID-19 vaccination, but VAERS itself warns that reports may be coincidental, incomplete or unverified and cannot be used to calculate rates or prove causation.
• There is credible evidence for rare neurological adverse events after some COVID-19 vaccines: for example, CDC/ACIP found an elevated Guillain-Barré syndrome reporting rate after the Janssen vaccine, and a Nature Medicine self-controlled case-series found small absolute increases in certain neurological outcomes after vaccination. This supports a much narrower claim of rare risks, not a tenfold overall rise.
• I found no reliable population-level evidence supporting the specific numerical claims that COVID vaccines tripled miscarriage rates, tripled cancer rates, or caused a tenfold rise in neurological conditions.

• Miscarriage: A large Vaccine Safety Datalink study in JAMA found no increased odds of spontaneous abortion after COVID-19 vaccination during pregnancy; the adjusted odds ratio was about 1.02, not a tripling.
• Miscarriage: NEJM v-safe pregnancy registry surveillance found pregnancy outcomes after mRNA vaccination broadly similar to expected background rates and did not identify a miscarriage safety signal.
• Cancer: The U.S. National Cancer Institute states there is no evidence that COVID-19 vaccines cause cancer, make cancer recur, or make cancer more aggressive. The claim of a tripling of cancer rates is not supported by cancer authorities or credible epidemiologic data.
• Neurological conditions: Large vaccine-safety surveillance studies did identify rare adverse events, but not a tenfold general increase in neurological conditions. JAMA Vaccine Safety Datalink surveillance of millions of mRNA-vaccine recipients did not find broad serious safety signals for monitored outcomes.
• Neurological conditions: The Nature Medicine study found the absolute excess risks after vaccination were small and that SARS-CoV-2 infection itself was associated with substantially higher neurological risks than vaccination for several outcomes.
• The statement combines three sweeping causal and quantitative claims without specifying population, time period, vaccine type, baseline rates, or case definitions; the best available high-quality evidence contradicts the miscarriage and broad neurological claims and provides no support for a cancer-rate tripling.

94/100 — the lab’s own confidence in the score above, not a second reading of the claim.

VAERS/HHSgov · 80 · JAMAjournal · 94 · New England Journal of Medicinejournal · 92 · National Cancer Institutegov · 92 · JAMAjournal · 93 · Nature Medicinejournal · 93 · CDC MMWRgov · 90

• The specific figures in this claim (tripling of cancer/miscarriages and a tenfold rise in neurological conditions) originate from a January 2022 panel hosted by U.S. Senator Ron Johnson. During the panel, attorney Thomas Renz presented data pulled from the Defense Medical Epidemiology Database (DMED).
• The raw DMED data queried at the time showed an apparent 300% increase in cancer and miscarriages, and an approximately 1,000% increase in neurological diagnoses among U.S. military personnel in 2021 compared to the average of the previous five years (2016-2020).
• Advocates of this claim also frequently cite unverified, self-reported data from the Vaccine Adverse Event Reporting System (VAERS) to allege widespread increases in these conditions post-vaccination.

• The Department of Defense (DoD) investigated the DMED anomalies and confirmed that a database glitch caused a massive underreporting of medical conditions for the years 2016 through 2020. Because the 2016-2020 baseline data was artificially and erroneously low, the accurate 2021 data created the statistical illusion of a massive spike, when in reality 2021 numbers were consistent with normal historical levels.
• Extensive, peer-reviewed epidemiological studies analyzing hundreds of thousands of pregnancies have conclusively shown that COVID-19 vaccination does not increase the risk of miscarriage (spontaneous abortion).
• Global cancer registries and long-term safety monitoring by agencies like the CDC, FDA, and European Medicines Agency (EMA) show zero evidence that COVID-19 vaccines cause, accelerate, or increase the rates of cancer.
• While some extremely rare neurological side effects (such as Guillain-Barré syndrome associated with viral vector vaccines) have been documented, there is no tenfold rise in neurological conditions. Medical studies consistently demonstrate that a COVID-19 infection carries a significantly higher risk of neurological complications than the vaccines.

98/100 — the lab’s own confidence in the score above, not a second reading of the claim.

Journal of the American Medical Association (JAMA)journal · 95 · New England Journal of Medicinejournal · 95

• Some early reports using CDC v-safe pregnancy-registry data produced a 12.6% miscarriage figure among 827 completed pregnancies, and critics argued that this denominator could make the rate appear misleadingly low or high; however, this is not evidence of a tripling relative to the background rate. Reuters reported that the relevant estimate among pregnancies vaccinated in the first or second trimester was about 3.65% under one calculation, while later CDC analysis estimated the cumulative risk at about 12.8%, within the expected range.[https://www.reuters.com/article/fact-check/data-from-a-study-does-not-conclude-that-over-80-of-pregnancies-end-in-miscarri-idUSL1N2OX1WL/]
• A 2024 case-crossover study reported mixed stratified results and a non-statistically significant adjusted odds ratio of 1.65 for miscarriage, with a confidence interval spanning no effect; this does not establish a tripling.[https://www.nature.com/articles/s41598-024-57880-8]
• The claim may draw on temporal or ecological observations about cancer diagnoses or neurological conditions, but such observations cannot establish that vaccination caused those outcomes, and no cited evidence demonstrates the claimed threefold or tenfold increases.

• The CDC reported that its analysis of nearly 2,500 pregnant people who received an mRNA vaccine before 20 weeks found no increased miscarriage risk; the approximately 13% cumulative risk was similar to the established background estimate of roughly 11–16%.[https://archive.cdc.gov/www_cdc_gov/media/releases/2021/s0811-vaccine-safe-pregnant.html]
• A large prospective cohort study published in Human Reproduction found that COVID-19 vaccination before conception was not associated with an increased miscarriage rate.[https://academic.oup.com/humrep/article/38/12/2362/7326030]
• A systematic review and meta-analysis reported a pooled miscarriage rate of 9% among 123,185 vaccinated women, consistent with expected rates and not evidence of a tripling.[https://pmc.ncbi.nlm.nih.gov/articles/PMC10152171/]
• The CDC states that studies involving more than one million pregnant women found no increased health risks for pregnant people or their babies from vaccination before or during pregnancy.[https://www.cdc.gov/covid/vaccines/pregnant-or-breastfeeding.html]
• FactCheck.org found that the apparent miscarriage claim resulted from misinterpreting the v-safe denominator and reported that the age-adjusted cumulative risk was 12.8%, within the expected range.[https://www.factcheck.org/2021/07/cdc-data-thus-far-show-covid-19-vaccination-safe-during-pregnancy/]
• FactCheck.org reported that there is no evidence linking COVID-19 vaccination to increased cancer risk.[https://www.factcheck.org/2024/05/still-no-evidence-covid-19-vaccination-increases-cancer-risk-despite-posts/]
• Reuters reported that there is no evidence of a causal link between COVID-19 vaccines and increased cancer cases; it also noted that increases in cancer diagnoses among younger adults predated the vaccines.[https://www.reuters.com/fact-check/rise-under-50s-cancer-diagnoses-predates-covid-19-vaccines-2025-01-20/]
• Reuters fact-checked claims that COVID-19 vaccines caused increased cancer and found no supporting evidence.[https://www.reuters.com/article/fact-check/no-evidence-covid-19-vaccines-have-caused-increase-in-cancers-contrary-to-claim-idUSL1N2UM24J/]
• The retrieved evidence contains no credible epidemiological study, government assessment, or fact-check establishing a tenfold increase in neurological conditions caused by COVID-19 vaccination. The absence of such evidence, together with the lack of a plausible demonstrated population-level signal of that magnitude, weighs strongly against the neurological component of the claim.

93/100 — the lab’s own confidence in the score above, not a second reading of the claim.

U.S. Centers for Disease Control and Preventiongov · 98 · U.S. Centers for Disease Control and Preventiongov · 98 · Human Reproduction / Oxford Academicjournal · 96 · National Library of Medicine, systematic review and meta-analysisjournal · 94 · Scientific Reports / Nature Portfoliojournal · 90 · FactCheck.orgfactcheck · 93 · FactCheck.orgfactcheck · 93 · Reutersnews · 94 · Reutersnews · 94 · Reutersnews · 92

• VAERS and similar passive reporting systems contain post-vaccination reports of miscarriage, cancers, and neurological diagnoses that some commentators treat as evidence of large causal increases.
• A minority of preprints, alternative-health analyses, and social-media interpretations of insurance or excess-mortality data have been cited as showing temporal associations after rollout.
• Theoretical arguments about spike protein, inflammation, or lipid nanoparticles have been offered as biological plausibility by proponents.

• Large pregnancy registries and cohort studies (v-safe, Vaccine Safety Datalink and similar) found miscarriage rates after mRNA vaccination consistent with the well-established 11-20% background rate, not a tripling.
• National cancer registries and vital-statistics systems show no tripling of overall cancer incidence coinciding with vaccination campaigns; observed changes are far smaller and largely explained by pandemic disruptions to screening.
• Population surveillance of neurological conditions shows no tenfold rise; documented vaccine-associated neurological events (e.g., rare GBS with certain products) occur at orders of magnitude below a population-wide tenfold increase.
• COVID-19 infection itself carries higher documented risks of miscarriage, stillbirth, and neurological complications than vaccination.
• Ongoing pharmacovigilance by CDC, FDA, EMA and WHO has not identified signals supporting the claimed magnitudes or causation.

82/100 — the lab’s own confidence in the score above, not a second reading of the claim.

New England Journal of Medicinejournal · 95 · CDC/FDA VAERSgov · 80