SARS-CoV-2 mass vaccination: Urgent questions on vaccine safety
that demand answers from international health agencies, regulatory
authorities, governments and vaccine developers
Roxana Bruno1, Peter A Mccullough2, Teresa Forcades I Vila3, Alexandra Henrion-Caude4,
Teresa Garc´ıa-Gasca5, Galina P Zaitzeva6, Sally Priester7, Mar´ıa J Mart´ınez Albarrac´ın8,
Alejandro Sousa-Escandon9, Fernando L´opez Mirones10, Bartomeu Payeras Cifre11 ,
Almudena Zaragoza Velilla10, Leopoldo M Borini1, Mario Mas1, Ramiro Salazar1, Edgardo
Schinder1, Eduardo A Yahbes1, Marcela Witt1, Mariana Salmeron1, Patricia Fern´andez1,
Miriam M Marchesini1, Alberto J Kajihara1, Marisol V De La Riva1, Patricia J Chimeno1,
Paola A Grellet1, Matelda Lisdero1, Pamela Mas1, Abelardo J Gatica Baudo12, Elisabeth
Retamoza12, Oscar Botta13 , Chinda C Brandolino13, Javier Sciuto14, Mario Cabrera
Avivar14, Mauricio Castillo15, Patricio Villarroel15, Emilia P Poblete Rojas15, B´arbara
Aguayo15, Dan I Mac´ıas Flores15, Jose V Rossell16, Julio C Sarmiento17, Victor
Andrade-Sotomayor17, Wilfredo R Stokes Baltazar18, Virna Cede˜no Escobar19, Ulises
Arr´ua20, Atilio Farina del R´ıo21, Tatiana Campos Esquivel22, Patricia Callisperis23, Mar´ıa
Eugenia Barrientos24, Christian Fiala25, and Karina Acevedo-Whitehouse26
1Epidemi´ologos Argentinos Metadisciplinarios
2Baylor University Medical Center
3Monestir de Sant Benet de Montserrat
4Simplissima International Research Institute, Mauritius.
5School of Natural Sciences, Autonomous University of Quer´etaro
6Retired Professor of Medical Immunology. Universidad de Guadalajara. Mexico
7M´edicos por la Verdad Puerto Rico
8Retired Professor of Clinical Diagnostic Processes. University of Murcia. Spain
9Hospital Comarcal de Monforte, University of Santiago de Compostela, Spain
10Bi´ologos por la Verdad, Espa˜na
11Retired Biologist. University of Barcelona. Specialized in Microbiology. Spain
12Center for Integrative Medicine MICAEL (Medicina Integrativa Centro Antropos´oﬁco
Educando en Libertad). Argentina
13M´edicos por la Verdad Argentina
14M´edicos por la Verdad Uruguay
15M´edicos por la Libertad Chile
16Physician, orthopedic specialist. Chile
17M´edicos por la Verdad Per´u
18M´edicos por la Verdad Guatemala
19Centro de Biotecnolog´ıas ´
Omicas (CEBIOMICS) - Concepto Azul, Ecuador
20M´edicos por la Verdad Brasil
21M´edicos por la Verdad Paraguay
22M´edicos por la Verdad Costa Rica
23M´edicos por la Verdad Bolivia
24M´edicos por la Verdad El Salvador
25Gynmed Ambulatorium, Vienna. Austria
26Aﬃliation not available
May 20, 2021
Since the start of the COVID-19 outbreak, the race for testing new platforms designed to confer immunity against SARS-CoV-2,
has been rampant and unprecedented, leading to conditional emergency authorization of various vaccines. Despite progress on
early multidrug therapy for COVID-19 patients, the current mandate is to immunize the world population as quickly as possible.
The lack of thorough testing in animals prior to clinical trials, and authorization based on safety data generated during trials
that lasted less than 3.5 months, raise questions regarding vaccine safety. The recently identiﬁed role of SARS-CoV-2 Spike
glycoprotein for inducing endothelial damage characteristic of COVID-19, even in absence of infection, is extremely relevant
given that most of the authorized vaccines induce endogenous production of Spike. Given the high rate of occurrence of adverse
eﬀects that have been reported to date, as well as the potential for vaccine-driven disease enhancement, Th2-immunopathology,
autoimmunity, and immune evasion, there is a need for a better understanding of the beneﬁts and risks of mass vaccination,
particularly in groups excluded from clinical trials. Despite calls for caution, the risks of SARS-CoV-2 vaccination have been
minimized or ignored by health organizations and government authorities. As for any investigational biomedical program, data
safety monitoring boards (DSMB) and event adjudication committees (EAC), should be enacting risk mitigation. If DSMBs
and EACs do not do so, we will call for a pause in mass vaccination. If DSMBs and EACs do not exist, then vaccination should
be halted immediately, in particular for demographic groups at highest risk of vaccine-associated death or serious adverse
eﬀects, during such time as it takes to assemble these boards and commence critical and independent assessments. We urge for
pluralistic dialogue in the context of health policies, emphasizing critical questions that require urgent answers, particularly if
we wish to avoid a global erosion of public conﬁdence in science and public health.
SARS-CoV-2 mass vaccination: Urgent questions on vaccine safety that demand answers from
international health agencies, regulatory authorities, governments and vaccine developers
Roxana Bruno1, Peter A. McCullough2, Teresa Forcades i Vila3, Alexandra Henrion-Caude4, Teresa Garc´ıa-
Gasca5, Galina P. Zaitzeva6, Sally Priester7, Mar´ıa J. Mart´ınez Albarrac´ın8, Alejandro Sousa-Escandon9, Fer-
nando L´opez Mirones10 , Bartomeu Payeras Cifre11, Almudena Zaragoza Velilla10 , Leopoldo M. Borini1, Mario
Mas1, Ramiro Salazar1, Edgardo Schinder1, Eduardo A. Yahbes1, Marcela Witt1, Mariana Salmeron1, Patri-
cia Fern´andez1, Miriam M. Marchesini1, Alberto J. Kajihara1, Marisol V. de la Riva1, Patricia J. Chimeno1,
Paola A. Grellet1, Matelda Lisdero1, Pamela Mas1, Abelardo J. Gatica Baudo12, Elisabeth Retamoza12 ,
Oscar Botta13, Chinda C. Brandolino13 , Javier Sciuto14, Mario Cabrera Avivar14, Mauricio Castillo15, Pa-
tricio Villarroel15, Emilia P. Poblete Rojas15, B´arbara Aguayo15, Dan I. Mac´ıas Flores15 , Jose V. Rossell16,
Julio C. Sarmiento17, Victor Andrade-Sotomayor17, Wilfredo R. Stokes Baltazar18, Virna Cede˜no Escobar19,
Ulises Arr´ua20, Atilio Farina del R´ıo21, Tatiana Campos Esquivel22, Patricia Callisperis23, Mar´ıa Eugenia
Barrientos24, Christian Fiala25 , Karina Acevedo-Whitehouse5,*.
1Epidemi´ologos Argentinos Metadisciplinarios. Argentina.
2Baylor University Medical Center. Dallas, Texas. USA.
3Monestir de Sant Benet de Montserrat, Montserrat. Spain
4Simplissima International Research Institute. Mauritius.
5School of Natural Sciences. Autonomous University of Quer´etaro. Mexico.
6Retired Professor of Medical Immunology. Universidad de Guadalajara. Mexico.
7M´edicos por la Verdad Puerto Rico. Ashford Medical Center, San Juan. Puerto Rico.
8Retired Professor of Clinical Diagnostic Processes. University of Murcia. Spain.
9Hospital Comarcal de Monforte, University of Santiago de Compostela, Spain.
10 Bi´ologos por la Verdad. Spain.
11 Retired Biologist. University of Barcelona. Specialized in Microbiology. Spain.
12 Center for Integrative Medicine MICAEL (Medicina Integrativa Centro Antropos´oﬁco Educando en Li-
13 M´edicos por la Verdad. Argentina. ´
14 M´edicos por la Verdad. Uruguay.
15 M´edicos por la Libertad. Chile.
16 Physician, orthopedic specialist. Chile.
17 M´edicos por la Verdad. Per´u.
18 M´edicos por la Verdad. Guatemala.
19 Centro de Biotecnolog´ıas ´
Omicas (CEBIOMICS) - Concepto Azul, Ecuador.
20 M´edicos por la Verdad. Brasil.
21 M´edicos por la Verdad. Paraguay.
22 M´edicos por la Verdad. Costa Rica.
23 M´edicos por la Verdad. Bolivia.
24 M´edicos por la Verdad. El Salvador.
25 Gynmed Ambulatorium, Vienna. Austria.
Since the start of the COVID-19 outbreak, the race for testing new platforms designed to confer immunity
against SARS-CoV-2, has been rampant and unprecedented, leading to conditional emergency authorization
of various vaccines. Despite progress on early multidrug therapy for COVID-19 patients, the current mandate
is to immunize the world population as quickly as possible. The lack of thorough testing in animals prior to
clinical trials, and authorization based on safety data generated during trials that lasted less than 3.5 months,
raise questions regarding vaccine safety. The recently identiﬁed role of SARS-CoV-2 Spike glycoprotein for
inducing endothelial damage characteristic of COVID-19, even in absence of infection, is extremely relevant
given that most of the authorized vaccines induce endogenous production of Spike. Given the high rate
of occurrence of adverse eﬀects that have been reported to date, as well as the potential for vaccine-driven
disease enhancement, Th2-immunopathology, autoimmunity, and immune evasion, there is a need for a better
understanding of the beneﬁts and risks of mass vaccination, particularly in groups excluded from clinical
trials. Despite calls for caution, the risks of SARS-CoV-2 vaccination have been minimized or ignored by
health organizations and government authorities. As for any investigational biomedical program, data safety
monitoring boards (DSMB) and event adjudication committees (EAC), should be enacting risk mitigation.
If DSMBs and EACs do not do so, we will call for a pause in mass vaccination. If DSMBs and EACs do not
exist, then vaccination should be halted immediately, in particular for demographic groups at highest risk
of vaccine-associated death or serious adverse eﬀects, during such time as it takes to assemble these boards
and commence critical and independent assessments. We urge for pluralistic dialogue in the context of health
policies, emphasizing critical questions that require urgent answers, particularly if we wish to avoid a global
erosion of public conﬁdence in science and public health.
Since COVID-19 was declared a pandemic in March 2020, over 150 million cases and 3 million cases of deaths
from or with SARS-CoV-2 have been reported worldwide. Despite progress on early ambulatory, multidrug-
therapy for high-risk patients, resulting in 85% reductions in COVID-19 hospitalization and death , the
current paradigm for control is mass-vaccination. While we recognize the eﬀort involved in development,
production and emergency authorization of SARS-CoV-2 vaccines, we are concerned that risks have been
minimized or ignored by health organizations and government authorities, despite calls for caution [2-8].
Vaccines for other coronaviruses have never been approved for humans, and data generated in the develop-
ment of coronavirus vaccines designed to elicit neutralizing antibodies show that they may worsen COVID-19
disease via antibody-dependent enhancement (ADE) and Th2 immunopathology, regardless of the vaccine
platform and delivery method [9-11]. Vaccine-driven disease enhancement in animals vaccinated against
SARS-CoV and MERS-CoV is known to occur following viral challenge, and has been attributed to immune
complexes and Fc-mediated viral capture by macrophages, which augment T-cell activation and inﬂammation
In March 2020, vaccine immunologists and coronavirus experts assessed SARS-CoV-2 vaccine risks based on
SARS-CoV-vaccine trials in animal models. The expert group concluded that ADE and immunopathology
were a real concern, but stated that their risk was insuﬃcient to delay clinical trials, although continued
monitoring would be necessary . While there is no clear evidence of the occurrence of ADE and vaccine-
related immunopathology in volunteers immunized with SARS-CoV-2 vaccines , safety trials to date have
not speciﬁcally addressed these serious adverse eﬀects (SAE). Given that the follow-up of volunteers did not
exceed 2-3.5 months after the second dose [16-19], it is unlikely such SAE would have been observed. Despite
errors in reporting, it cannot be ignored that even accounting for the number of vaccines administered,
according to the US Vaccine Adverse Eﬀect Reporting System (VAERS), the number of deaths per million
vaccine doses administered has increased more than 10-fold. We believe there is an urgent need for open
scientiﬁc dialogue on vaccine safety in the context of large-scale immunization. In this paper, we describe
some of the risks of mass vaccination in the context of phase 3 trial exclusion criteria and discuss the SAE
reported in national and regional adverse eﬀect registration systems. We highlight unanswered questions and
draw attention to the need for a more cautious approach to mass vaccination.
SARS-CoV-2 phase 3 trial exclusion criteria
With few exceptions, SARS-CoV-2 vaccine trials excluded the elderly [16-19], making it impossible to identify
the occurrence of post-vaccination eosinophilia and enhanced inﬂammation in elderly people. Studies of
SARS-CoV vaccines showed that immunized elderly mice were at particularly high risk of life-threatening
Th2 immunopathology [9,20]. Despite this evidence and the extremely limited data on safety and eﬃcacy of
SARS-CoV-2 vaccines in the elderly, mass-vaccination campaigns have focused on this age group from the
start. Most trials also excluded pregnant and lactating volunteers, as well as those with chronic and serious
conditions such as tuberculosis, hepatitis C, autoimmunity, coagulopathies, cancer, and immune suppression
[16-29], although these recipients are now being oﬀered the vaccine under the premise of safety.
Another criterion for exclusion from nearly all trials was prior exposure to SARS-CoV-2. This is unfortunate
as it denied the opportunity of obtaining extremely relevant information concerning post-vaccination ADE
in people that already have anti-SARS-Cov-2 antibodies. To the best of our knowledge, ADE is not being
monitored systematically for any age or medical condition group currently being administered the vaccine.
Moreover, despite a substantial proportion of the population already having antibodies , tests to determine
SARS-CoV-2-antibody status prior to administration of the vaccine are not conducted routinely.
Will serious adverse eﬀects from the SARS-CoV-2 vaccines go unnoticed?
COVID-19 encompasses a wide clinical spectrum, ranging from very mild to severe pulmonary pathology
and fatal multi-organ disease with inﬂammatory, cardiovascular, and blood coagulation dysregulation [22-24].
In this sense, cases of vaccine-related ADE or immunopathology would be clinically-indistinguishable from
severe COVID-19 . Furthermore, even in the absence of SARS-CoV-2 virus, Spike glycoprotein alone
causes endothelial damage and hypertension in vitro and in vivo in Syrian hamsters by down-regulating
angiotensin-converting enzyme 2 (ACE2) and impairing mitochondrial function . Although these ﬁndings
need to be conﬁrmed in humans, the implications of this ﬁnding are staggering, as all vaccines authorized
for emergency use are based on the delivery or induction of Spike glycoprotein synthesis. In the case of
mRNA vaccines and adenovirus-vectorized vaccines, not a single study has examined the duration of Spike
production in humans following vaccination. Under the cautionary principle, it is parsimonious to consider
vaccine-induced Spike synthesis could cause clinical signs of severe COVID-19, and erroneously be counted
as new cases of SARS-CoV-2 infections. If so, the true adverse eﬀects of the current global vaccination
strategy may never be recognized unless studies speciﬁcally examine this question. There is already non-
causal evidence of temporary or sustained increases in COVID-19 deaths following vaccination in some
countries (Fig. 1) and in light of Spike’s pathogenicity, these deaths must be studied in depth to determine
whether they are related to vaccination.
Unanticipated adverse reactions to SARS-CoV-2 vaccines
Another critical issue to consider given the global scale of SARS-CoV-2 vaccination is autoimmunity. SARS-
CoV-2 has numerous immunogenic proteins, and all but one of its immunogenic epitopes have similarities to
human proteins . These may act as a source of antigens, leading to autoimmunity . While it is true that
the same eﬀects could be observed during natural infection with SARS-CoV-2, vaccination is intended for
most of the world population, while it is estimated that only 10% of the world population has been infected
by SARS-CoV-2, according to Dr. Michael Ryan, head of emergencies at the World Health Organization.
We have been unable to ﬁnd evidence that any of the currently authorized vaccines screened and excluded
homologous immunogenic epitopes to avoid potential autoimmunity due to pathogenic priming.
Some adverse reactions, including blood-clotting disorders, have already been reported in healthy and
young vaccinated people. These cases led to the suspension or cancellation of the use of adenoviral vec-
torized ChAdOx1-nCov-19 and Janssen vaccines in some countries. It has now been proposed that vacci-
nation with ChAdOx1-nCov-19 can result in immune thrombotic thrombocytopenia (VITT) mediated by
platelet-activating antibodies against Platelet factor-4, which clinically mimics autoimmune heparin-induced
thrombocytopenia . Unfortunately, the risk was overlooked when authorizing these vaccines, although
adenovirus-induced thrombocytopenia has been known for more than a decade, and has been a consistent
event with adenoviral vectors . The risk of VITT would presumably be higher in those already at risk of
blood clots, including women who use oral contraceptives , making it imperative for clinicians to advise
their patients accordingly.
At the population level, there could also be vaccine-related impacts. SARS-CoV-2 is a fast-evolving RNA virus
that has so far produced more than 40,000 variants [32,33] some of which aﬀect the antigenic domain of Spike
glycoprotein [34,35]. Given the high mutation rates, vaccine-induced synthesis of high levels of anti-SARS-
CoV-2-Spike antibodies could theoretically lead to suboptimal responses against subsequent infections by
other variants in vaccinated individuals , a phenomenon known as “original antigenic sin”  or antigenic
priming . It is unknown to what extent mutations that aﬀect SARS-CoV-2 antigenicity will become ﬁxed
during viral evolution , but vaccines could plausibly act as selective forces driving variants with higher
infectivity or transmissibility. Considering the high similarity between known SARS-CoV-2 variants, this
scenario is unlikely [32,34] but if future variants were to diﬀer more in key epitopes, the global vaccination
strategy might have helped shape an even more dangerous virus. This risk has recently been brought to the
attention of the WHO as an open letter .
The risks outlined here are a major obstacle to continuing global SARS-CoV-2 vaccination. Evidence on the
safety of all SARS-CoV-2 vaccines is needed before exposing more people to the risk of these experiments,
since releasing a candidate vaccine without time to fully understand the resulting impact on health could
lead to an exacerbation of the current global crisis . Risk-stratiﬁcation of vaccine recipients is essential.
According to the UK government, people below 60 years of age have an extremely low risk of dying from
COVID-19. However, according to Eudravigillance, most of the serious adverse eﬀects following SARS-
CoV-2 vaccination occur in people aged 18-64. Of particular concern is the planned vaccination schedule for
children aged 6 years and older in the United States and the UK. Dr. Anthony Fauci recently anticipated that
teenagers across the country will be vaccinated in the autumn and younger children in early 2022, and the UK
is awaiting trial results to commence vaccination of 11 million children under 18. There is a lack of scientiﬁc
justiﬁcation for subjecting healthy children to experimental vaccines, given that the Centers for Disease
Control and Prevention estimates that they have a 99.997% survival rate if infected with SARS-CoV-2. Not
only is COVID-19 irrelevant as a threat to this age group, but there is no reliable evidence to support vaccine
eﬃcacy or eﬀectiveness in this population or to rule out harmful side eﬀects of these experimental vaccines.
In this sense, when physicians advise patients on the elective administration of COVID-19 vaccination, there
is a great need to better understand the beneﬁts and risk of administration, particularly in understudied
In conclusion, in the context of the rushed emergency-use-authorization of SARS-CoV-2 vaccines, and the
current gaps in our understanding of their safety, the following questions must be raised:
* Is it known whether cross-reactive antibodies from previous coronavirus infections or vaccine-induced
antibodies may inﬂuence the risk of unintended pathogenesis following vaccination with COVID-19?
* Has the speciﬁc risk of ADE, immunopathology, autoimmunity, and serious adverse reactions been
clearly disclosed to vaccine recipients to meet the medical ethics standard of patient understanding for
informed consent? If not, what are the reasons, and how could it be implemented?
* What is the rationale for administering the vaccine to every individual when the risk of dying from
COVID-19 is not equal across age groups and clinical conditions and when the phase 3 trials excluded the
elderly, children and frequent speciﬁc conditions?
* What are the legal rights of patients if they are harmed by a SARS-CoV-2 vaccine? Who will cover
the costs of medical treatment? If claims were to be settled with public money, has the public been made
aware that the vaccine manufacturers have been granted immunity, and their responsibility to compensate
those harmed by the vaccine has been transferred to the tax-payers?
If vaccination programs worldwide do not institute independent data safety monitoring boards (DSMB),
event adjudication committees (EAC), and enact risk mitigation, we will call for a pause in the mass vacci-
nation program. If DSMBs and EACs do not exist currently, as would be imperative for any investigational
biomedical program, then vaccination should be immediately halted for those demographic groups at highest
risk of vaccine-associated death or serious adverse eﬀects, during the time it takes to assemble these boards
and committees and commence their assessments.
In the context of these concerns, we propose opening an urgent pluralistic, critical, and scientiﬁcally-based
dialogue on SARS-CoV-2 vaccination among scientists, medical doctors, international health agencies, reg-
ulatory authorities, governments, and vaccine developers. This is the only way to bridge the current gap
between scientiﬁc evidence and public health policy regarding the SARS-CoV-2 vaccines. We are convinced
that humanity deserves a deeper understanding of the risks than what is currently touted as the oﬃcial
position. An open scientiﬁc dialogue is urgent and indispensable to avoid erosion of public conﬁdence in
science and public health and to ensure that the WHO and national health authorities protect the interests of
humanity during the current pandemic. Returning public health policy to evidence-based medicine, relying
on a careful evaluation of the relevant scientiﬁc research, is urgent. It is imperative to follow the science.
Conﬂict of Interest Statement
The authors declare that the research was conducted in the absence of any commercial or ﬁnancial relation-
ships that could be construed as a potential conﬂict of interest.
1. McCullough PA, Alexander PE, Armstrong R, et al. Multifaceted highly targeted sequential multidrug
treatment of early ambulatory high-risk SARS-CoV-2 infection (COVID-19). Rev Cardiovasc Med (2020)
2. Arvin AM, Fink K, Schmid MA, et al. A perspective on potential antibody- dependent enhancement
of SARS-CoV-2. Nature (2020) 484:353–363. doi:10.1038/s41586-020-2538-8
3. Coish JM, MacNeil AJ. Out of the frying pan and into the ﬁre? Due diligence warranted for ADE
in COVID-19. Microbes Infect (2020) 22(9):405-406. doi:10.1016/j.micinf.2020.06.006
4. Eroshenko N, Gill T, Keaveney ML, et al. Implications of antibody-dependent enhancement of infection
for SARS-CoV-2 countermeasures. Nature Biotechnol (2020) 38:788–797. doi:10.1038/s41587-020-0577-1
5. Poland GA. Tortoises, hares, and vaccines: A cautionary note for SARS-CoV-2 vaccine development.
Vaccine (2020) 38:4219–4220. doi:10.1016/j.vaccine.2020.04.073
6. Shibo J. Don’t rush to deploy COVID-19 vaccines and drugs without suﬃcient safety guarantees.
Nature (2000) 579,321. doi:10.1038/d41586-020-00751-9
7. Munoz FA, Cramer JP, Dekker CL, et al. Vaccine-associated enhanced disease: Case deﬁnition
and guidelines for data collection, analysis, and presentation of immunization safety data. Vaccine (2021)
8. Cardozo T, Veazey R. Informed consent disclosure to vaccine trial subjects of risk of COVID-19
vaccines worsening clinical disease. Int J Clin Pract (2020) 28:e13795. doi: 10.1111/ijcp.13795
9. Bolles D, Long K, Adnihothram S, et al. A double-inactivated severe acute respiratory syndrome coro-
navirus vaccine provides incomplete protection in mice and induces increased eosinophilic proinﬂammatory
pulmonary response upon challenge. J Virol (2001) 85:12201–12215. doi:10.1128/JVI.06048-11
10. Weingartl H, Czub M, Czub S, et al. Immunization with modiﬁed vaccinia virus Ankarabased
recombinant vaccine against severe acute respiratory syndrome is associated with enhanced hepatitis in
ferrets. J Virol (2004) 78:12672–12676. doi:10.1128/JVI.78.22.12672-12676.2004
11. Tseng CT, Sbrana E, Iwata-Yoshikawa N, et al. Immunization with SARS coronavirus vaccines leads
to pulmonary immunopathology on challenge with the SARS virus. PLoS One (2012) 7(4):e35421. doi:
12. Iwasaki A, Yang Y. The potential danger of suboptimal antibody responses in COVID-19. Nat Rev
Immunol (2020) 20:339–341. doi:10.1038/s41577-020-0321-6
13. Vennema H, de Groot RJ, Harbour DA, et al. Early death after feline infectious peritonitis virus
challenge due to recombinant vaccinia virus immunization. J Virol (1990) 64:1407-1409
14. Lambert PH, Ambrosino DM, Andersen SR, et al. Consensus summary report for CEPI/BC March
12-13, 2020 meeting: Assessment of risk of disease enhancement with COVID-19 vaccines. Vaccine (2020)
15. de Alwis R, Chen S, Gan S, et al. Impact of immune enhancement on Covid-19 polyclonal hyperimmune
globulin therapy and vaccine development. EbioMedicine (2020) 55:102768. doi:10.1016/j.ebiom.2020.102768
16. Folegatti PM, Ewer KJ, Aley PK, et al. Safety and immunogenicity of the ChAdOx1 nCoV-19 vaccine
against SARS-CoV-2: a preliminary report of a phase 1/2, single-blind, randomised controlled trial. Lancet
(2020) 396:467–783. doi:10.1016/S0140-6736(20)31604-4
17. Polack FP, Thomas SJ, Kitchin N. Safety and eﬃcacy of the BNT162b2 mRNA Covid-19 vaccine. N
Engl J Med (2020) 383:2603–2615. doi:10.1056/NEJMoa2034577
18. Ramasamy MN, Minassian AM, Ewer KJ, et al. Safety and immunogenicity of ChAdOx1 nCoV-19 vac-
cine administered in a prime-boost regimen in young and old adults (COV002): a single-blind, randomised,
controlled, phase 2/3 trial. Lancet (2021) 396:1979–93. doi: 10.1016/S0140-6736(20)32466-1
19. Chu L, McPhee R, Huang W, et al. mRNA-1273 Study Group. A preliminary report of a randomized
controlled phase 2 trial of the safety and immunogenicity of mRNA-1273 SARS-CoV-2 vaccine. Vaccine
(2021) S0264-410X(21)00153-5. doi:10.1016/j.vaccine.2021.02.007
20. Liu L, Wei Q, Lin Q, et al. Anti-spike IgG causes severe acute lung injury by skewing macrophage re-
sponses during acute SARS-CoV infection. JCI Insight (2019) 4(4):e123158. doi:10.1172/jci.insight.123158.
21. Ioannidis PA. Infection fatality rate of COVID-19 inferred from seroprevalence data. Bull WHO (2021)
22. Martines RB, Ritter JM, Matkovic E, et al. Pathology and Pathogenesis of SARS-CoV-
2 Associated with Fatal Coronavirus Disease, United States Emerg Infect Dis (2020) 26:2005-2015.
23. Wu Z, McGoogan JM. Characteristics of and Important Lessons From the Coronavirus Disease 2019
(COVID-19) Outbreak in China: Summary of a Report of 72 314 Cases From the Chinese Center for Disease
Control and Prevention. JAMA (2020) 323:1239-1242. doi:10.1001/jama.2020.2648
24. Xu Z, Shi L, Wang Y, et al. Pathological ﬁndings of COVID-19 associated with acute respiratory
distress syndrome. Lancet Respiratory Med (2020) 8:420-422 doi:10.1016/S2213-2600(20)30076-X
25. Negro F. Is antibody-dependent enhancement playing a role in COVID-19 pathogenesis? Swiss Medical
Weekly (2020) 150:w20249. doi:10.4414/smw.2020.20249
26. Lei Y, Zhang J, Schiavon CR et al., Spike Protein Impairs Endothelial Function via Downregulation
of ACE 2. Circulation Res (2021) 128:1323–1326. https://doi.org/10.1161/CIRCRESAHA.121.318902
27. Lyons-Weiler J. Pathogenic priming likely contributes to serious and critical illness
and mortality in COVID-19 via autoimmunity, J Translational Autoimmunity (2020) 3:100051.
28. An H, Park J. Molecular Mimicry Map (3M) of SARS-CoV-2: Prediction of potentially im-
munopathogenic SARS-CoV-2 epitopes via a novel immunoinformatic approach. bioRxiv [Preprint]. 12
November 2020 [cited 2020 April 19] https://doi.org/10.1101/2020.11.12.344424
29. Greinacher A, Thiele T, Warkentin TE, Weisser K, Kyrle PA, Eichinger S. Thrombotic Thrombocy-
topenia after ChAdOx1 nCov-19 Vaccination. N Engl J Med (2021). doi: 10.1056/NEJMoa2104840
30. Othman M, Labelle A, Mazzetti I et al. Adenovirus-induced thrombocytopenia: the role of von
Willebrand factor and P-selectin in mediating accelerated platelet clearance. Blood (2007) 109:2832–2839.
31. Ortel TL. Acquired thrombotic risk factors in the critical care setting. Crit Care Med (2010) 38(2
32. Grubaugh ND, Petrone ME, Holmes EC. We shouldn’t worry when a virus mutates during disease
outbreaks. Nat Microbiol (2020) 5:529–530. https://doi.org/10.1038/s41564-020-0690-4
33. Greaney AJ, Starr TN, Gilchuk P, et al. Complete Mapping of Mutations to the SARS-CoV-2
Spike Receptor-Binding Domain that Escape Antibody Recognition. Cell Host Microbe (2021) 29:44–57.e9.
34. Lauring AS, Hodcroft EB. Genetic Variants of SARS-CoV-2—What Do They Mean? JAMA (2021)
35. Zhang L, Jackson CB, Mou H, et al. The D614G mutation in the SARS-CoV-2 spike protein
reduces S1 shedding and increases infectivity. bioRxiv [Preprint]. June 12 2020 [cited 2021 Apr 19]
36. Korber B, Fischer WM, Gnanakaran S et al. Sheﬃeld COVID-19 Genomics Group. Tracking
changes in SARS-CoV-2 spike: evidence that D614G increases infectivity of the COVID-19 virus. Cell (2020)
37. Francis T. On the doctrine of original antigenic sin. Proc Am Philos Soc (1960) 104:572–578.
38. Vibroud C, Epstein SL. First ﬂu is forever. Science (2016) 354:706–707. doi:10.1126/science.aak9816
39. Weisblum Y, Schmidt F, Zhang F, et al. Escape from neutralizing antibodies by SARS-CoV-2 spike
protein variants. Elife (2020) 9:e61312. doi:10.7554/eLife.61312
40. Vanden Bossche G (March 6, 2021) https://dryburgh.com/wp- content/uploads/2021/03/Geert_
41. Coish JM, MacNeil AJ. Out of the frying pan and into the ﬁre? Due diligence warranted for ADE in
COVID-19. Microbes Infect (2020) 22(9):405-406. doi:10.1016/j.micinf.2020.06.006
Figure 1: Number of new COVID-19 deaths in relation to number of people that have received at least one
vaccine dose for selected countries. Graph shows data from the start of vaccination to May 3rd, 2021. A)
India (9.25% of population vaccinated), B) Thailand (1.58% of population vaccinated), C) Colombia (6.79%
of population vaccinated), D) Mongolia (31.65% of population vaccinated), E) Israel (62.47% of population
vaccinated), F) Entire world (7.81% of population vaccinated). Graphs were built using data from Our
World in Data (accessed 4 May 2021) https://github.com/owid/covid-19-data/tree/master/public/
 (https://www.gov.uk/government/publications/covid-19-reported-sars- cov-2-deaths-in-