Introduction
Covid-19 vaccines were developed to lower the severity of Covid-19 symptoms and to prevent progression of the disease to either hospitalization or death. Despite these benefits, Covid-19 vaccines have unfortunately caused harms in a small proportion of the people receiving the shot. Given the ubiquity of Covid-19 vaccination, even a small per shot risk can amount to a large population of vaccine injured.
Vaccine injury can be divided into acute and post acute versions [
1]. The defined adverse events are largely treated similarly regardless of etiological agent, while post acute vaccine syndrome (PACVS) currently eludes diagnostic criteria as well as rigorous validation of treatment protocols. The development of diagnostics and treatment protocols are intertwined problems, as typically diagnostics can be used to guide and evaluate treatment, while treatments may be based on understandings of biological mechanisms associated with diagnostic biomarkers.
Importantly, a greater understanding of disease mechanism now as opposed to at the beginning of the vaccine rollout, or the start of the pandemic for that matter. Both Covid-19 and the vaccine rollout have introduced novel disease types in the population, motivating the development of clinical strategies.
PACVS is characterized by a disease phenotype similar to myalgic encephalomyelitis /chronic fatigue syndrome (ME/CFS), involving fatigue, dysautonomia, post exertional malaise and sometimes neuropathic pain and cognitive disturbances [
2].
Barriers to Receiving Care
In addition to the difficulty in diagnosing and treating a condition that is currently ill defined and receives little research attention, there are other barriers to receiving care. The physical ailments can be debilitating [
3], and the vaccine injured have difficulty accessing compensation [
4], and the option of suing manufacturers is eliminated due to government legislation [
5,
6]. In addition to this, the vaccine injured can often face marginalization, which often makes it more difficult to have their condition accepted [
7]. We launched a survey on October 25, 2024 and collected responses up to December 31, 2024 to assess what were the barriers to receiving care for the vaccine injured. Using a similar format to a previous survey for Lyme disease [
8], we modified the questions to make them appropriate for vaccine injured participants.
Vaccine injury is unnecessarily politicized because the phenomenon undermines narratives of vaccine safety and calls into question objectives to achieve full vaccination coverage and to disempower vaccine hesitancy. Lyme disease may be an even more relevant comparison owing to conspiracism about its origin. If we examine the timeline of several controversial syndromes attributed to an etiological factor (i.e. not idiopathic). Besides Lyme disease, another controversial syndrome was ‘Gulf War Illness’, named because it afflicted US servicemen and women returning from Desert Storm.
Fortunately with PACVS, the etiological agent is known, though exact understanding of disease mechanisms are still elusive. While debate over the etiological factors driving Gulf War Illness, the literature attributes it to chemical hazards and toxins, including sarin gas. Other possible factors may drive Gulf War Syndrome.
Similarly Lyme disease emerged through epidemiology, where people in Lyme, Connecticut and surrounding areas began developing a novel syndrome in the 1960’s and 1970’s, leading to its recognition in 1976 [
9]. It wasn’t until 1981 that the etiological agent, the spirochetal bacteria
Borrelia burgdorferi, was identified [
10].
For both case, sufferers of each disease have experienced marginalization, a lack of effective treatment options, and gaslighting by physicians and the medical establishment. A comparison of the conditions is available in
Table 1.
Methods
We created an online survey using Google Forms (geni.us/VITAE) and disseminated it through a series of social media posts of the FLCCC. We ran the survey from October 25, 2024 until December 31, 2024 and received completed surveys from 705 participants. The structure of the survey was based off a previous survey performed for Lyme disease, which is another condition in which patients feel marginalized and have difficulty receiving care (8).
Results
Demographic Characteristics of Respondents
Referring to
Table 2 we can see that the survey encompassed a broad age distribution, with the largest group of respondents born between 1960–1969 (190 participants, 26.95%), followed by those born between 1950–1959 (162 participants, 22.98%). Representation of younger age groups was minimal, with only 2 respondents (0.28%) born between 2000–2010. Gender distribution indicated a predominance of females (63.92%), compared to males (36.08%).
Regional representation was diverse but primarily focused on North America, with 82.7% of respondents residing there. Contributions from Australia/Oceania (7.23%) and Europe (5.82%) underscore the global nature of the issue. These demographic insights establish a foundational understanding of the respondent pool, critical for contextualizing subsequent findings.
Duration and Diagnosis of Post-Vaccination Syndrome
Table 3 shows that a majority of respondents (79.57%) reported symptoms persisting for over two years, illustrating the chronicity of the condition. Only 4.4% experienced symptoms for less than six months, emphasizing the long-term burden experienced by the vaccine-injured population. Chronic symptoms lasting six months or more post-treatment were reported by 91.35% of participants, highlighting the inadequacy of current interventions.
Interestingly, 33.33% of participants had preexisting chronic health conditions, while 66.67% reported no prior health issues, suggesting that post-vaccination syndrome affects individuals irrespective of their baseline health status. Diagnosis predominantly relied on patient history and non-specific laboratory tests (78.87%), with only 21.13% being diagnosed through specific spike protein or antibody tests. Diagnostic delays were notable, with 33.65% seeing 2-3 physicians, and 30.95% consulting 4-6 physicians before receiving a diagnosis. A significant subset (5.87%) saw over 20 physicians, underscoring the systemic challenges in timely identification.
Treatment Accessibility and Healthcare Barriers
From
Table 4 we can see that the treatment access varied, with 73.05% of respondents traveling less than 50 miles for care, whereas 6.52% traveled over 500 miles, reflecting geographic inequities in care availability. Approximately 55.18% sought treatment at local hospitals, yet nearly half of these (49.93%) reported difficulties in obtaining care. Such barriers highlight the pressing need for more accessible and equitable healthcare systems.
Insurance coverage emerged as a critical issue, with 86.1% of participants not applying for new medical insurance post-diagnosis. Of those who applied, 5.56% faced rejection due to their condition. Moreover, 15.6% reported that insurers mandated a diagnosis of long COVID to cover treatment, adding bureaucratic hurdles to an already burdensome condition. Public support or disability benefits were accessed by only 12.77% of respondents, indicating systemic limitations in financial assistance for the vaccine-injured.
Financial Impacts and Employment Disruptions
Referring to
Table 5 we see that the monthly medical expenses varied widely, with 34.96% spending less than
$200, while 12.75% incurred costs exceeding
$2500. Out-of-pocket costs followed a similar pattern, with 39.83% spending under
$200 and 5.73% exceeding
$2500. These figures underscore the financial strain experienced by affected individuals.
Employment outcomes were significantly impacted, with 26.79% not working at the time of injury and 26.36% becoming unemployed due to their condition. Among employed respondents, 16.19% reported working at slightly reduced capacity, while 9.89% managed significantly reduced workloads. Only 10.89% maintained their pre-injury work capacity. Annual income reductions were stark; the proportion of respondents earning less than $30,000 annually increased from 21.95% pre-injury to 46.2% post-injury, highlighting the economic toll of the syndrome.
Of the 511 individuals employed at the time of injury, the average income drop was 0.80 categories, using the categories shown in
Table 5. Breaking down the results, only 2.5% of individuals experienced an increase in their income category, while 31.7% retained their original category. The majority of the sample, 46.2%, dropped by one income category. Notably, a significant portion, 24.3% of individuals, experienced a more severe decline, dropping by more than one income category. These figures suggest a general downward trend in income categories for the studied population, with nearly 70% of individuals experiencing some level of decline.
Therefore, this analysis underscores the profound health, financial, and systemic challenges faced by individuals with post-vaccination syndrome. Chronic symptoms, diagnostic delays, barriers to care, and significant economic impacts collectively illustrate the urgent need for targeted interventions. Enhanced diagnostic criteria, equitable healthcare access, and robust financial support systems are imperative to alleviate the burden borne by this vulnerable population.
Discussion
In this article, we present the result of a survey of people experiencing post vaccination syndrome, revealing a high degree of continuing debility and financial impacts. The survey received 705 responses, and accompanies a body of work on the disease burden of post-vaccination syndrome [
3]. One limitation of the study is that it is self-reported, and we could not verify the diagnosis of post vaccination syndrome. Currently, each diagnosis of PACVS must be done in a bespoke manner, and it is not recognized as an official disease entity. The development of diagnostic tests for Lyme disease aided the recognition for that disease, and similarly, an urgent task exists for acknowledgement and diagnostics development for PACVS [
2,
25,
28].
Further development of this work could be quantifying the disease burden of PACVS, and comparing it to other diseases. Given the relationship between disease burden and level of NIH funding [
29], quantitative estimates may help to make the case for greater research funding. Additionally, producing educational resources for physicians, and disseminating information on post vaccination syndrome may improve accessibility, the average number of doctors visited before diagnosis was 6.9. Accessibility of care is also a concern, as 15% of those surveyed travel over 100 miles for treatment (
Table 3).
Lastly, financial resources for those affected should be mustered, as the average out-of-pocket treatment cost was
$573, and those affected have also had significantly reduced work capacity, affecting their income. Almost 2/3 (63%) of the respondents employed at the time of their injury have had a 50% or greater reduction in their work capacity, with a full 36% of respondents employed at the time of their injury now unemployed (
Table 5). For those employed at the time of injury, the average decrease in yearly income was
$29 178.
These results help to establish the disease burden of PACVS and the barriers to care that PACVS patients experience. Our results may motivate research into treatments, as well as reform for compensation for this condition.
References
- Scholkmann, F.; May, C.A. COVID-19, post-acute COVID-19 syndrome (PACS, “long COVID”) and post-COVID-19 vaccination syndrome (PCVS, “post-COVIDvac-syndrome”): Similarities and differences. Pathol - Res Pract. 2023, 246, 154497. [CrossRef]
- Mundorf, A.K.; Semmler, A.; Heidecke, H.; Schott, M.; Steffen, F.; Bittner, S., et al. Clinical and Diagnostic Features of Post-Acute COVID-19 Vaccination Syndrome (PACVS). Vaccines 2024, 12, 790. [CrossRef]
- Krumholz, H.M.; Wu, Y.; Sawano, M.; Shah, R.; Zhou, T.; Arun, A.S., et al. Post-Vaccination Syndrome: A Descriptive Analysis of Reported Symptoms and Patient Experiences After Covid-19 Immunization. medRxiv. 2023 Nov 10;2023.11.09.23298266. [CrossRef]
- Office USGA. COVID-19: Information on HHS’s Medical Countermeasures Injury Compensation Program | U.S. GAO [Internet]. [cited 2024 Dec 27]. Available from: https://www.gao.gov/products/gao-25-107368.
- Hickey KJ. The PREP Act and COVID-19, Part 1: Statutory Authority to Limit Liability for Medical Countermeasures. Congr Res Serv CRS Rep Issue Briefs. 2022 Apr 1;NA-NA.
- Federal Register [Internet]. 2020 [cited 2024 Dec 30]. Fourth Amendment to the Declaration Under the Public Readiness and Emergency Preparedness Act for Medical Countermeasures Against COVID-19 and Republication of the Declaration. Available from: https://www.federalregister.gov/documents/2020/12/09/2020-26977/fourth-amendment-to-the-declaration-under-the-public-readiness-and-emergency-preparedness-act-for.
- Heyerdahl LW, Dielen S, Nguyen T, Riet CV, Kattumana T, Simas C, et al. Doubt at the core: Unspoken vaccine hesitancy among healthcare workers. Lancet Reg Health – Eur [Internet]. 2022 Jan 1 [cited 2024 Dec 27];12. Available from: https://www.thelancet.com/journals/lanepe/article/PIIS2666-7762(21)00275-1/fulltext. [CrossRef]
- Johnson L, Aylward A, Stricker RB. Healthcare access and burden of care for patients with Lyme disease: A large United States survey. Health Policy. 2011 Sep 1;102(1):64–71. [CrossRef]
- Steere AC, Coburn J, Glickstein L. The emergence of Lyme disease. J Clin Invest. 2004 Apr 15;113(8):1093–101. [CrossRef]
- Johnson RC, Schmid GP, Hyde FW, Steigerwalt AG, Brenner DJ. Borrelia burgdorferi sp. nov.: Etiologic Agent of Lyme Disease. Int J Syst Evol Microbiol. 1984;34(4):496–7. [CrossRef]
- Elbaum-Garfinkle S. Close to Home: A History of Yale and Lyme Disease. Yale J Biol Med. 2011 Jun;84(2):103–8.
- Greenberg N, Wessely S. Gulf War syndrome: an emerging threat or a piece of history? Emerg Health Threats J. 2008 Nov 27;1:e10. [CrossRef]
- Steere AC. Lyme Arthritis: A 50-Year Journey. J Infect Dis. 2024 Aug 15;230(Supplement_1):S1–10. [CrossRef]
- Illness GW. the Health of Gulf War Veterans: Scientific Findings and Recommendations. Binns JH Comm Chair US Gov Print Off Wash DC. 2008;
- Safavi F, Gustafson L, Walitt B, Lehky T, Dehbashi S, Wiebold A, et al. Neuropathic symptoms with SARS-CoV-2 vaccination [Internet]. medRxiv; 2022 [cited 2025 Jan 4]. p. 2022.05.16.22274439.
- Haley RW, Kramer G, Xiao J, Dever JA, Teiber JF. Evaluation of a Gene–Environment Interaction of PON1 and Low-Level Nerve Agent Exposure with Gulf War Illness: A Prevalence Case–Control Study Drawn from the U.S. Military Health Survey’s National Population Sample. Environ Health Perspect. 2022 May;130(5):057001. [CrossRef]
- STEERE AC, MALAWISTA SE, NEWMAN JH, SPIELER PN, BARTENHAGEN NH. Antibiotic Therapy in Lyme Disease. Ann Intern Med. 1980 Jul;93(1_Part_1):1–8. [CrossRef]
- Friedl KE, Grate SJ, Proctor SP. Neuropsychological Issues in Military Deployments: Lessons Observed in the DoD Gulf War Illnesses Research Program. Mil Med. 2009 Apr;174(4):335–46. [CrossRef]
- US Department of Veterans Affairs. CSP #475 - Persian Gulf - Antibiotic Treatment Trial of Gulf War Veterans' Illnesses [Internet]. clinicaltrials.gov; 2023 Oct [cited 2025 Jan 4]. Report No.: NCT00007735. Available from: https://clinicaltrials.gov/study/NCT00007735.
- Chester JE, Rowneki M, Van Doren W, Helmer DA. Progression of intervention-focused research for Gulf War illness. Mil Med Res. 2019 Oct 18;6:31. [CrossRef]
- Wormser GP, McKenna D, Karmen CL, Shaffer KD, Silverman JH, Nowakowski J, et al. Prospective Evaluation of the Frequency and Severity of Symptoms in Lyme Disease Patients With Erythema Migrans Compared With Matched Controls at Baseline, 6 Months, and 12 Months. Clin Infect Dis Off Publ Infect Dis Soc Am. 2020 Jan 23;71(12):3118–24. [CrossRef]
- Engdahl BE, James LM, Miller RD, Leuthold AC, Lewis SM, Carpenter AF, et al. Brain Function in Gulf War Illness (GWI) and Associated Mental Health Comorbidities. J Neurol Neuromedicine. 2018;3(4):24–34.
- Bobe JR, Jutras BL, Horn EJ, Embers ME, Bailey A, Moritz RL, et al. Recent Progress in Lyme Disease and Remaining Challenges. Front Med [Internet]. 2021 Aug 18 [cited 2025 Jan 4];8. [CrossRef]
- Chao LL. Examining the current health of Gulf War veterans with the veterans affairs frailty index. Front Neurosci [Internet]. 2023 Sep 7 [cited 2025 Jan 4];17. [CrossRef]
- Platschek B, Boege F. The Post-Acute COVID-19-Vaccination Syndrome in the Light of Pharmacovigilance. Vaccines. 2024 Dec;12(12):1378. [CrossRef]
- Research Portfolio Online Reporting Tools. RePORT [Internet]. [cited 2025 Jan 4]. Available from: https://report.nih.gov/funding/categorical-spending#/.
- Gulf War Illness Research Program: Strategic Plan [Internet]. CDMRP Department of Defense; 2020 May. Available from: https://cdmrp.health.mil/gwirp/pdfs/GWIRP%20Strategic%20Plan.pdf.
- Semmler A, Mundorf AK, Kuechler AS, Schulze-Bosse K, Heidecke H, Schulze-Forster K, et al. Chronic Fatigue and Dysautonomia following COVID-19 Vaccination Is Distinguished from Normal Vaccination Response by Altered Blood Markers. Vaccines. 2023 Nov;11(11):1642. [CrossRef]
- Gillum LA, Gouveia C, Dorsey ER, Pletcher M, Mathers CD, McCulloch CE, et al. NIH Disease Funding Levels and Burden of Disease. PLOS ONE. 2011 Feb 24;6(2):e16837. [CrossRef]
Table 1.
A comparison on the timelines and degree of official recognition between Lyme disease, Gulf War Illness and Post acute covid-19 Vaccination Syndrome (PACVS).
Table 1.
A comparison on the timelines and degree of official recognition between Lyme disease, Gulf War Illness and Post acute covid-19 Vaccination Syndrome (PACVS).
| Event |
Lyme disease |
Gulf War Syndrome |
Post Covid-19 vaccination syndrome |
| Emergence of symptoms |
1975 in Lyme, CT [11] |
1991 [12] |
2020 during trials 2021 during vaccine rollout |
| Recognition as disease entity |
1977 [13] |
2008 [14] |
Recognized by scientific community early on in 2022 [15] but lacking official recognition |
| Etiological agent discovered |
Borrelia burgdorferi discovered in 1981 [10] |
Strong evidence for exposure to sarin nerve gas being the cause in 2022 [16] |
Known at time of injuries, i.e. in 2021 |
| First clinical trials of treatment options |
1980 [17] |
1994: US Department of Defense establishes Gulf War Veterans' Illnesses Research Program (GWVIRP) [18] 1999 [19,20] |
None |
| Prevalence of fatigue in those with condition |
51.9% (early Lyme) [21] |
28.1% [22] |
69% [3] |
| Number Affected |
476 000 diagnosed per year in USA [23] |
250 000 [24] |
Approximately 0.9% of vaccine recipients [25] or up to 2 million people in the USA |
| Annual Funding |
$43 million (2023) [26] |
$20 million [27] |
No specific funding |
Table 2.
Demographic Characteristics of Respondents (n = 705).
Table 2.
Demographic Characteristics of Respondents (n = 705).
| Birth Year |
n |
% |
| 2011 or later |
1 |
0.1 |
| 2000–2010 |
20 |
2.8 |
| 1990–2000 |
33 |
4.7 |
| 1980–1989 |
79 |
11.2 |
| 1970–1979 |
114 |
16.2 |
| 1960–1969 |
190 |
27.0 |
| 1950–1959 |
162 |
23.0 |
| 1940–1949 |
87 |
12.3 |
| 1930–1939 |
19 |
2.7 |
| Gender |
n |
% |
| Male |
254 |
36.1 |
| Female |
450 |
63.9 |
| Region |
n |
% |
| North America |
583 |
82.7 |
| Australia/Oceania |
51 |
7.2 |
| Europe |
41 |
5.8 |
| Others |
30 |
4.3 |
Table 3.
Duration and Diagnosis of Post-Vaccination Syndrome (n = 705).
Table 3.
Duration and Diagnosis of Post-Vaccination Syndrome (n = 705).
| Duration Of Post Vaccination Syndrome |
n |
% |
| Greater than 2 years |
561 |
79.6 |
| 1 to 2 years |
81 |
11.5 |
| 6 months to 1 year |
32 |
4.5 |
| Less than 6 months |
31 |
4.4 |
| Did you have any chronic health problems before your Post-Vaccination Syndrome diagnosis? |
n |
% |
| Yes |
235 |
33.3 |
| No |
470 |
66.7 |
| Do you have chronic symptoms (lasting 6 months or more) after receiving treatment for Post-Vaccination Syndrome? |
n |
% |
| Yes |
644 |
91.3 |
| No |
61 |
8.7 |
| How were you diagnosed with Post-Vaccination Syndrome? |
n |
% |
| Laboratory test for spike protein or spike antibodies with patient history |
149 |
21.1 |
| Patient history with other laboratory tests |
556 |
78.9 |
| How many physicians did you see between your onset of symptoms and a Post-Vaccination Syndrome diagnosis? |
n |
% |
| 21 or more |
37 |
5.2 |
| 16-20 |
26 |
3.7 |
| 10-15 |
70 |
9.9 |
| 7–9 |
90 |
12.8 |
| 4–6 |
195 |
27.7 |
| 2–3 |
212 |
30.1 |
| 1 |
75 |
10.6 |
Table 4.
Responses related to treatment access (n = 705).
Table 4.
Responses related to treatment access (n = 705).
| What is the distance you currently travel for treatment of your Post-Vaccination Syndrome? |
n |
% |
| Greater than 500 miles |
46 |
6.5 |
| 101–500 miles |
61 |
8.7 |
| 51–100 miles |
83 |
11.8 |
| Less than 50 miles |
515 |
73.1 |
| Have you ever visited your local hospital for treatment of your Post-Vaccination Syndrome? |
n |
% |
| Yes |
389 |
55.2 |
| No |
316 |
44.8 |
| If you visited your local hospital, did you experience difficulty in obtaining treatment? |
n |
% |
| Yes |
351 |
49.9 |
| No |
352 |
50.1 |
| Since your Post-Vaccination Syndrome diagnosis, have you applied for a new medical insurance policy? |
n |
% |
| Yes |
98 |
13.9 |
| No |
607 |
86.1 |
| If you applied for a new medical insurance policy, were you turned down based on your Post-Vaccination Syndrome diagnosis? |
n |
% |
| Yes |
39 |
5.6 |
| No |
663 |
94.4 |
| Has your medical insurer ever required that you see a long COVID specialist or modify your diagnosis to long COVID to cover your treatment? |
n |
% |
| Yes |
110 |
15.6 |
| No |
595 |
84.4 |
| Have you ever been on public support or received disability benefits due to Post-Vaccination Syndrome? |
n |
% |
| Yes |
90 |
12.8 |
| No |
615 |
87.2 |
| If you have received public support or disability benefits, how long did you receive them? |
n |
% |
| More than 2 years |
42 |
6.0 |
| 12–23 months |
20 |
2.8 |
| 7–11 months |
11 |
1.6 |
| 6 months or less |
29 |
4.1 |
| Non-Applicable |
601 |
85.5 |
| How many times have you visited an emergency department because of Post-Vaccination Syndrome? |
n |
% |
| Greater than 10 times |
30 |
4.3 |
| 6–10 times |
37 |
5.3 |
| 3–5 times |
112 |
15.9 |
| Twice |
104 |
14.8 |
| Never |
295 |
41.8 |
| Once |
127 |
18.0 |
Table 5.
Financial Impacts of Post-Vaccination Syndrome (n = 705).
Table 5.
Financial Impacts of Post-Vaccination Syndrome (n = 705).
| What is the total cost of your medical treatment per month? |
n |
% |
| Greater than $2501 |
89 |
12.75 |
|
$1001 to $2500 |
90 |
12.89 |
|
$501 to $1000 |
106 |
15.19 |
|
$201 to $500 |
169 |
24.21 |
| Below $200 |
244 |
34.96 |
| What is the out-of-pocket cost of your medical treatment per month? |
n |
% |
| Greater than $2501 |
40 |
5.73 |
|
$1001 to $2500 |
74 |
10.6 |
|
$501 to $1000 |
113 |
16.19 |
|
$201 to $500 |
193 |
27.65 |
| Below $200 |
278 |
39.83 |
| Have you been able to continue working since your injury? |
n |
% |
| Yes, at significantly reduced capacity (~50% of previous workload) |
69 |
9.89 |
| Yes, at greatly reduced capacity (25% or less of previous workload) |
69 |
9.89 |
| Yes, at slightly reduced capacity (75% or greater of previous workload) |
113 |
16.19 |
| Yes, at the same capacity |
76 |
10.89 |
| Was not working at time of injury |
187 |
26.79 |
| No, Unemployed |
184 |
26.36 |
| What was your yearly income prior to your injury? |
n |
% |
|
$200,000 or more |
77 |
11.05 |
|
$100,000 - $199,999 |
150 |
21.52 |
|
$60,000 - $99,999 |
174 |
24.96 |
|
$30,000 - $59,999 |
143 |
20.52 |
| Less than $30,000 |
153 |
21.95 |
| What is your yearly income after your injury? |
n |
% |
|
$200,000 or more |
49 |
7.03 |
|
$100,000 - $199,999 |
75 |
10.76 |
|
$60,000 - $99,999 |
127 |
18.22 |
|
$30,000 - $59,999 |
124 |
17.79 |
| Less than $30,000 |
322 |
46.2 |
|
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