A 6-Week Time Period May not be Sufficient to Identify Potential Adverse Events Following COVID-19 Vaccination


  • Hélène Banoun Pharmacist and biologist
  • Patrick Provost Full Professor, Faculty of Medicine and Researcher, Infectious and Immune Diseases Axis, CHUL Pavilion https://orcid.org/0000-0002-6099-6562




adverse event reporting, cancer resurgence, cardiovascular diseases, pharmacological records, respiratory disease, sanitary measures for COVID-19, varicella zoster symptoms, zona after vaccination


Background. Messenger RNA (mRNA) vaccines have been widely used as the main sanitary measure destined to fight the COVID-19 pandemic. Rapidly purported as being “safe and effective”, this new generation of vaccines is radically different from those developed traditionally and for which potentially associated adverse events (AEs) are considered through a standard 6-week post-vaccination period.

Hypothesis. Here, we posit that the reporting period for AEs related to the COVID-19 vaccines may need to be longer.

Method. In this retrospective, observational study, we aimed to assess the chronology of new/worsening ailments occurring after the administration of COVID-19 vaccines based on the changes to the participants’ pharmacological records. Patients vaccinated against COVID-19 and experiencing health-related events during the study period (between September 30, 2021 and July 15, 2022) were included and the changes to their pharmacological records were analyzed.

Results. One hundred and twelve (112) adult patients (63 men, 49 women; 67.54 ± 14.55 years-old; mean ± standard deviation) have reported changes to their pharmacological record following health-related events, which occurred 11.57 weeks (median; range 0.04-47.14) following their last COVID-19 injection of 3 doses (median; range 1-4). The most frequent medical ailments that appeared or worsened were cardiovascular diseases (CVD; N=61), cancer (N=31), respiratory diseases (RD; N=22) and zona (N=10), half of which occurred after the second dose. Nineteen (19) patients (10 men, 9 women; 78.2 ± 11.4 years-old) died on average 17.14 weeks (SD 13.71) after their last injection.

Conclusion. Most (76.1%) of the health-related events experienced by patients vaccinated against COVID-19 occurred beyond the 6-week period prescribed by the health authorities. Our findings call for further investigations and an extension of the post-vaccination AE reporting period.

Author Biographies

  • Hélène Banoun, Pharmacist and biologist

    Former INSERM researcher, retired, Marseille 13000, France

  • Patrick Provost, Full Professor, Faculty of Medicine and Researcher, Infectious and Immune Diseases Axis, CHUL Pavilion

    Department of Microbiology, Infectious Diseases and Immunology; Faculty of Medicine, Université Laval, Quebec City, QC, Canada; also, Researcher, Infectious and Immune Diseases Axis, CHU de Québec Research Center/CHUL Pavilion, 2705 Blvd Laurier, Room T1-65, Québec, QC, G1V 4G2, Canada


Banoun H. Why are children and many adults not affected by COVID-19? Role of the host immune response. Infect Dis Res. 2022;3(3):18. doi:10.53388/IDR20220825018. https://hal.archives-ouvertes.fr/hal-03754848

Boudemaghe T, Léger L, Perez-Martin A, Suehs CM, Gris J-C. Change in incidence of cardiovascular diseases during the covid-19 pandemic and vaccination campaign: data from the nationwide French hospital discharge database, medRxiv 2022.08.01.22278235; doi: https://doi.org/10.1101/2022.08.01.22278235

Buchan SA, Seo CY, Johnson C, Alley S, Kwong JC, Nasreen S, Calzavara A, Lu D, Harris TM, Yu K, Wilson SE. Epidemiology of Myocarditis and Pericarditis Following mRNA Vaccination by Vaccine Product, Schedule, and Interdose Interval Among Adolescents and Adults in Ontario, Canada. JAMA Netw Open. 2022 Jun 1;5(6):e2218505. doi: 10.1001/jamanetworkopen.2022.18505. PMID: 35749115; PMCID: PMC9233237. https://pubmed.ncbi.nlm.nih.gov/35749115/

Buchhorn R, Meyer C, Schulze-Forster K, Junker J, Heidecke H. Autoantibody Release in Children after Corona Virus mRNA Vaccination: A Risk Factor of Multisystem Inflammatory Syndrome? Vaccines. 2021; 9(11):1353. https://doi.org/10.3390/vaccines9111353

Crommelin DJA, Anchordoquy TJ, Volkin DB, Jiskoot W, Mastrobattista E. Addressing the cold reality of mRNA vaccine stability. J Pharm Sci 2021;110:997-1001. doi: 10.1016/j.xphs.2020.12.006 PMID: 33321139. https://pubmed.ncbi.nlm.nih.gov/33321139/

Fraiman J, Erviti J, Jones M, Greenland S, Whelan P, Kaplan RM, Doshi P. Serious adverse events of special interest following mRNA COVID-19 vaccination in randomized trials in adults. Vaccine. 2022 Sep 22;40(40):5798-5805. doi: 10.1016/j.vaccine.2022.08.036. Epub 2022 Aug 31. PMID: 36055877; PMCID: PMC9428332. https://pubmed.ncbi.nlm.nih.gov/36055877/

Gutschi LM. Quality issues with mRNA Covid vaccine production. Nov. 2, 2022. https://www.bitchute.com/video/muB0nrznCAC4/

Hughes, DA. (2021). “COVID-19 vaccines” for children in the UK: A tale of establishment corruption. International Journal of Vaccine Theory, Practice, and Research, 2(1), 209–247. https://doi.org/10.56098/ijvtpr.v2i1.35

Karlstad Ø, Hovi P, Husby A, Härkänen T, Selmer RM, Pihlström N, Hansen JV, Nohynek H, Gunnes N, Sundström A, Wohlfahrt J, Nieminen TA, Grünewald M, Gulseth HL, Hviid A, Ljung R. SARS-CoV-2 Vaccination and Myocarditis in a Nordic Cohort Study of 23 Million Residents. JAMA Cardiol. 2022;7(6):600–612. doi:10.1001/jamacardio.2022.0583. https://pubmed.ncbi.nlm.nih.gov/35442390/

Kis Z, Kontoravdi C, Shattock R, Shah N. Resources, Production Scales and Time Required for Producing RNA Vaccines for the Global Pandemic Demand. Vaccines (Basel). 2020 Dec 23;9(1):3. doi: 10.3390/vaccines9010003. Erratum in: Vaccines (Basel). 2021 Mar 01;9(3): PMID: 33374802; PMCID: PMC7824664. https://pubmed.ncbi.nlm.nih.gov/33374802/

Klein N. Myocarditis analyses in the vaccine safety datalink: rapid cycle analyses and “head-to-head” product comparisons. https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-202110-20-21/08-COVID-Klein-508.pdf. Accessed on November 11, 2021

Kostoff RN, Briggs MB, Porter AL, Spandidos DA, Tsatsakis A. (2020). [Comment] COVID‑19 vaccine safety. International Journal of Molecular Medicine, 46, 1599-1602. https://doi.org/10.3892/ijmm.2020.4733

Kraaijeveld SR, Gur-Arie R, Jamrozik E. Against COVID-19 vaccination of healthy children. Bioethics. 2022 Jul;36(6):687-698. doi: 10.1111/bioe.13015. Epub 2022 Mar 25. PMID: 35332941. https://pubmed.ncbi.nlm.nih.gov/35332941/

Lazarus R, Klompas, M., Harvard Pilgrim Health Care, Inc, Steve Bernstein. Electronic support for public health-vaccine adverse event reporting system (ESP:VAERS), 2010. https://digital.ahrq.gov/ahrq-funded-projects/electronic-support-public-health-vaccine-adverse-event-reporting-system

Lyons-Weiler, J. (2020). Pathogenic priming likely contributes to serious and critical illness and mortality in COVID-19 via autoimmunity. Journal of Translational Autoimmunity, 3, 100051. https://doi.org/10.1016/j.jtauto.2020.100051

Maiese A, Baronti A, Manetti AC, Di Paolo M, Turillazzi E, Frati P, Fineschi V. Death after the Administration of COVID-19 Vaccines Approved by EMA: Has a Causal Relationship Been Demonstrated? Vaccines (Basel). 2022 Feb 16;10(2):308. doi: 10.3390/vaccines10020308. PMID: 35214765. https://pubmed.ncbi.nlm.nih.gov/35214765/

Mevorach D, Anis E, Cedar N, Bromberg M, Haas EJ, Nadir E, Olsha-Castell S, Arad D, Hasin T, Levi N, Asleh R, Amir O, Meir K, Cohen D, Dichtiar R, Novick D, Hershkovitz Y, Dagan R, Leitersdorf I, Ben-Ami R, Miskin I, Saliba W, Muhsen K, Levi Y, Green MS, Keinan-Boker L, Alroy-Preis S. Myocarditis after BNT162b2 mRNA Vaccine against Covid-19 in Israel. N Engl J Med. 2021 Dec 2;385(23):2140-2149. doi: 10.1056/NEJMoa2109730. Epub 2021 Oct 6. PMID: 34614328; PMCID: PMC8531987. https://pubmed.ncbi.nlm.nih.gov/34614328/

Montano D. Frequency and Associations of Adverse Reactions of COVID-19 Vaccines Reported to Pharmacovigilance Systems in the European Union and the United States. Front Public Health. 2022 Feb 3;9:756633. doi: 10.3389/fpubh.2021.756633. eCollection 2021. PMID: 35186864. https://pubmed.ncbi.nlm.nih.gov/35186864/

Nunez-Castilla, J, Stebliankin, V, Baral, P, Balbin, CA, Sobhan, M, Cickovski, T, Mondal, AM, Narasimhan, G, Chapagain, P, & Mathee, K. (2022). Potential autoimmunity resulting from molecular mimicry between SARS-CoV-2 Spike and human proteins. BioRxiv, 2021–08. https://doi.org/10.1101/2021.08.10.455737

Provost, P. (2023). The blind spot in COVID-19 vaccination policies: Under-reported adverse events. International Journal of Vaccine Theory, Practice, and Research, 3(1), 707–726. https://doi.org/10.56098/ijvtpr.v3i1.65

Patterson BK, Francisco EB, Yogendra R, Long E, Pise A, Beaty C, Osgood E, Bream J, Kreimer M, Vander Heide R, Guevara-Coto J, Mora R, Mora J. SARS-CoV-2 S1 Protein Persistence in SARS-CoV-2 Negative Post-Vaccination Individuals with Long COVID/ PASC-Like Symptoms, 12 July 2022, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-1844677/v1]

Röltgen K, Nielsen SCA, Silva O, Younes SF, Zaslavsky M, Costales C, Yang F, Wirz OF, Solis D, Hoh RA, Wang A, Arunachalam PS, Colburg D, Zhao S, Haraguchi E, Lee AS, Shah MM, Manohar M, Chang I, Gao F, Mallajosyula V, Li C, Liu J, Shoura MJ, Sindher SB, Parsons E, Dashdorj NJ, Dashdorj ND, Monroe R, Serrano GE, Beach TG, Chinthrajah RS, Charville GW, Wilbur JL, Wohlstadter JN, Davis MM, Pulendran B, Troxell ML, Sigal GB, Natkunam Y, Pinsky BA, Nadeau KC, Boyd SD. Immune imprinting, breadth of variant recognition, and germinal center response in human SARS-CoV-2 infection and vaccination. Cell. 2022 Mar 17;185(6):1025-1040.e14. doi: 10.1016/j.cell.2022.01.018. Epub 2022 Jan 25. PMID: 35148837; PMCID: PMC8786601. https://pubmed.ncbi.nlm.nih.gov/35148837/

Shimabukuro TT, Nguyen M, Martin D, DeStefano F. Safety monitoring in the Vaccine Adverse Event Reporting System (VAERS). Vaccine. 2015 Aug 26;33(36):4398-405. doi: 10.1016/j.vaccine.2015.07.035. Epub 2015 Jul 22. PMID: 26209838; PMCID: PMC4632204. https://pubmed.ncbi.nlm.nih.gov/26209838/

Shimizu J, Sasaki T, Koketsu R, Morita R, Yoshimura Y, Murakami A, Saito Y, Kusunoki T, Samune Y, Nakayama EE, Miyazaki K, Shioda T. Reevaluation of antibody-dependent enhancement of infection in anti-SARS-CoV-2 therapeutic antibodies and mRNA-vaccine antisera using FcR- and ACE2-positive cells. Sci Rep. 2022 Sep 16;12(1):15612. doi: 10.1038/s41598-022-19993-w. PMID: 36114224. https://pubmed.ncbi.nlm.nih.gov/36114224/

Sridhar P, Singh A, Salomon N, J. Steiger D. Vaccine-Induced Antibody Dependent Enhancement In COVID-19. Chest. 2022 Oct;162(4):A646–7. doi: 10.1016/j.chest.2022.08.506. Epub 2022 Oct 10. PMCID: PMC9548747. https://journal.chestnet.org/article/S0012-3692(22)01866-9/fulltext

Tinari S. The EMA covid-19 data leak, and what it tells us about mRNA instability. BMJ. 2021 Mar 10;372:n627. doi: 10.1136/bmj.n627. PMID: 33692030. https://pubmed.ncbi.nlm.nih.gov/33692030/

Tuvali O, Tshori S, Derazne E, Hannuna RR, Afek A, Haberman D, Sella G, George J. The Incidence of Myocarditis and Pericarditis in Post COVID-19 Unvaccinated Patients-A Large Population-Based Study. J Clin Med. 2022 Apr 15;11(8):2219. doi: 10.3390/jcm11082219. PMID: 35456309. https://pubmed.ncbi.nlm.nih.gov/35456309/

Vojdani, A, & Kharrazian, D. (2020). Potential antigenic cross-reactivity between SARS-CoV-2 and human tissue with a possible link to an increase in autoimmune diseases. Clinical Immunology (Orlando, Fla.), 217, 108480. https://doi.org/10.1016/j.clim.2020.108480

Vojdani, A, Vojdani, E, & Kharrazian, D. (2021). Reaction of human monoclonal antibodies to SARS-CoV-2 proteins with tissue antigens: Implications for autoimmune diseases. Frontiers in Immunology, 11, 617089. https://doi.org/10.3389/fimmu.2020.617089

Wong HL, Tworkoski E, Ke Zhou C, Hu M, Thompson D, Lufkin B, Do R, Feinberg L, Chillarige Y, Dimova R, Lloyd PC, MaCurdy T, Forshee RA, Kelman JA, Shoaibi A, Anderson SA. Surveillance of COVID-19 vaccine safety among elderly persons aged 65 years and older. Vaccine. 2022 Dec 1:S0264-410X(22)01493-1. doi: 10.1016/j.vaccine.2022.11.069. Epub ahead of print. PMID: 36496287; PMCID: PMC9712075. https://pubmed.ncbi.nlm.nih.gov/36496287/




How to Cite

A 6-Week Time Period May not be Sufficient to Identify Potential Adverse Events Following COVID-19 Vaccination. (2023). International Journal of Vaccine Theory, Practice, and Research , 3(1), 771-812. https://doi.org/10.56098/ijvtpr.v3i1.67

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