Population Studies and Their Limits

A growing number of post-pandemic reports have described cancer diagnoses, recurrence, or progression following COVID-19 vaccination or SARS-CoV-2 infection. While no causal relationship has been established, these observations raise important questions that warrant careful, hypothesis-driven investigation. ​​The rapid development and global distribution of mRNA and viral vector vaccines during the pandemic was a landmark achievement in public health, essential in reducing severe COVID-19 cases and mortality. However, the novelty of these vaccines and the absence of long-term carcinogenicity or genotoxicity testing have led some researchers to ask whether rare but biologically plausible interactions with cancer pathways might exist. At the same time, pandemic-related disruptions in routine cancer screening and treatment were anticipated to influence diagnosis patterns. Yet, some reports have described unexpected phenomena, such as rapid disease progression in previously stable cancers or tumor appearance near injection sites, that are not easily explained by delayed care alone. The Review: Examining 69 Studies on Cancer Diagnoses After COVID-19 Vaccination or Infection In a review published in Volume 17 of Oncotarget, titled “COVID vaccination and post-infection cancer signals: Evaluating patterns and potential biological mechanisms,” Charlotte Kuperwasser (Tufts University) and Oncotarget Editor-in-Chief Wafik S. El-Deiry (The Warren Alpert Medical School of Brown University) examined 69 peer-reviewed publications spanning January 2020 to October 2025. Full blog - https://www.oncotarget.org/2026/01/26/exploring-possible-links-between-covid-19-vaccination-infection-and-cancer/ Paper DOI - https://doi.org/10.18632/oncotarget.28824 Correspondence to - Charlotte Kuperwasser - charlotte.kuperwasser@tufts.edu, and Wafik S. El-Deiry - wafik@brown.edu Abstract video - https://www.youtube.com/watch?v=5_-AaojOoR8 Sign up for free Altmetric alerts about this article - https://oncotarget.altmetric.com/details/email_updates?id=10.18632%2Foncotarget.28824 Subscribe for free publication alerts from Oncotarget - https://www.oncotarget.com/subscribe/ Keywords - cancer, COVID, vaccine, infection, lymphoma, leukemia, sarcoma, carcinoma To learn more about Oncotarget, please visit https://www.oncotarget.com and connect with us: Facebook - https://www.facebook.com/Oncotarget/ X - https://twitter.com/oncotarget Instagram - https://www.instagram.com/oncotargetjrnl/ YouTube - https://www.youtube.com/@OncotargetJournal LinkedIn - https://www.linkedin.com/company/oncotarget Pinterest - https://www.pinterest.com/oncotarget/ Reddit - https://www.reddit.com/user/Oncotarget/ Spotify - https://open.spotify.com/show/0gRwT6BqYWJzxzmjPJwtVh MEDIA@IMPACTJOURNALS.COM