With the frenzied moment-by-moment reporting on COVID-19 virus cases now coupled with reports on the breakneck development of a vaccine for the pandemic, many within the Christian community have raised numerous legitimate concerns about vaccinations – are they necessary, effective, safe, or even ethical? And should vaccines be mandatory? Desiring to love your neighbor, practice stewardship, and submit to the governing authorities, while at the same time endeavoring to live faithfully under God’s authority, is challenging business at the best of times. During these worst of times, it’s downright distressing. Center stage in our present distress is the consideration of how we as Christians should respond to the issues surrounding vaccinations. And since the topic of immunizations is sure to raise emotional timbre and bring out divisions within the Christian community, how can this be done with grace and truth?
Although I’ve been the recipient of dozens of vaccines over my professional lifetime – many mandated for me to travel and work in overseas mission – and continue to promote annual flu immunizations for my elderly and at-risk patients, I’ve been shrewd enough to keep these matters on the down-low when in social circles, particularly at church (endeavoring to be a saint is one thing, but martyrdom is quite another). However, with the discussions of warp-speed COVID-19 vaccine development mounting to a fevered pitch, and with Big Pharma vaccines all vying for position to be the next big thing, flying under the radar seems less of an option for any of us. So, while I’m not against vaccinations, I do appreciate the raised concerns, particularly in reference to the COVID-19 vaccine development and projected implementation. The following is an attempt to address these matters through a Christian lens, and provide some clarity and equipping for the conversations ahead, as we each endeavor to reconcile all things under the Lordship of Christ.
Are Vaccines Necessary?
The origin of vaccines has a Christian heritage. Edward Jenner, who developed the first use of a vaccination back in 1796 against smallpox, was a vicar’s son and devout Christian. The fact he was a believer should be of no surprise; the Christian worldview alone provides the preconditions of intelligibility, and supplies the necessary foundation for the development of operational science and technology. Consequently, the modern scientific enterprise was launched largely by Christian believers who understood that loving God and loving neighbor were unified commandments, and that the use of our godly gifting was both an act of worship to God and a compassionate service to mankind. Credited today as the “father of immunology,†Jenner first observed that milkmaids with cowpox infection seemed to be protected from acquiring smallpox. Using fluid from a patient’s cowpox blister as an inoculum, he was able to demonstrate smallpox immunization, and put into motion a technique that would eventually spell the end of the millennia-old smallpox scourge.[1] Just last year, the World Health Organization (WHO) commemorated the 40th anniversary of smallpox eradication from the planet, a feat considered by many as the greatest achievement in international public health.
Since Jenner’s pioneering work, the scientific community has built on his model and developed numerous effective vaccines which have proven to be indispensable to the eradication of many diseases. Thanks to their innovations, once-raging epidemic storms have been quieted to mere isolated singular cases. Gone are the days of the iron lung for poliomyelitis, whooping cough quarantines, or the front-page reporting on diphtheria infant mortality. Diseases caused by a litany of pathogens – including poliomyelitis, pertussis, diphtheria, tetanus, measles, mumps, rubella, influenza, invasive Haemophilus influenza type b (Hib), hepatitis A and B, rotavirus, varicella, herpes zoster (shingles), Streptococcus pneumoniae, Neisseria meningitidis, and human papillomavirus (HPV) – have all been brought under manageable control. All of these serious diseases – estimated to have caused over 39 million infections during the twentieth century in the United States alone – are now largely preventable with our contemporary vaccination protocols.[2]
In fact, the impact of vaccination on the health of the world’s population is hard to exaggerate. With the exception of improvements in water supply and sanitation, no other intervention, not even antibiotic development, has had a greater reduction on mortality and allowed for greater global human flourishing. To be sure, vaccines represent the single most cost-effective life-saving innovation in all of medical history.[3] The enormous success of this public health intervention derives not only from the laborious identification of effective vaccines, but also from a multi-disciplinary infrastructure for vaccine manufacturing, rigorous regulatory and safety oversight, and streamlined approaches to delivery. With this in mind then, vaccines can be considered a manifestation of God’s grace, originally developed by members of His church, for the blessing of all humanity.
How do Vaccines Work?
Vaccines work by making use of our body’s natural defense mechanisms. Unlike antibiotics which counter infection by slowing pathogen reproduction, or by directly killing specific invading pathogens by damaging their cell walls, vaccines work indirectly, and protect us from pathogens by preparing our own immune system to do the countering and the killing. Our God-given immune response involves a complex array of specialized cells and protein mediators, which are busy night and day, 24/7 (statutory holidays included), on the job of surveillance and protection of our bodies, so that we can carry on with our lives, worry-free of infectious disease. Like a veritable army, our cellular defenses include macrophages, which function as frontline infantry, attacking and killing pathogens; dendritic cells, which have intelligence and reconnaissance functions, identifying pathogens and activating an amplified immune response; T-lymphocytes, which act like an armoured division, directly destroying pathogens in their path; and B-lymphocytes, which, when activated, function as microscopic weapons factories that produce specific antibodies with the capacity to neutralize invading pathogens. These B-lymphocytes also have a memory function, which is central to how vaccines protect. Once these cells have been warned about a particular pathogen by being shown its signature antigen contained in the vaccine, they never forget. In a dormant state, they remain on the look-out and ready to blow the whistle at the time of invasion, and set into motion a swift and sure immune response, which is nothing short of shock and awe on the cellular level. In brief, our elegantly designed immune system is breathtaking in scope, intricacy, coordination, and effectiveness, and one which we have yet to fully appreciate or understand. Praise be to God we don’t have to, in order to reap its lifesaving benefits.
Vaccines induce a protective immune response from our bodies by mimicking an active infection. This is done by allowing pathogen-specific red-flag foreign material, or antigens, to get exposure to our immune system, so that neutralizing antibodies are produced. Numerous distinct strategies are used in vaccine development to accomplish this. Conventional vaccines contain materials either originating from a microorganism (virus-based) or consisting of material synthesized to resemble certain key components of the pathogen (protein-based). The viral-based vaccines contain either live-attenuated virus (weakened), inactivated whole virus (no longer infectious), or virus-like particles, which consist of only the structural proteins without the genetic core (also non-infectious). Most licensed vaccines – such as those for influenza, measles, mumps, poliomyelitis, and rubella viruses – make use of the live-attenuated variety or inactivated natural pathogens to elicit immunity. Other conventional vaccines involve pathogen subunits (such as the vaccine against recombinant hepatitis B), inactivated toxins (such as vaccines against diphtheria and tetanus), surface carbohydrates (such as vaccines against pneumococcus), or a combination of subunits (as in vaccines against Haemophilus influenzae type B or meningococcus). All of these conventional vaccines contain antigens capable of activating our immune system, and stimulating the production of neutralizing antibodies directed to the respective infection of concern.
How are Vaccines Produced?
Production of conventional vaccines is a time-consuming and arduous process, and requires the use of egg cultures or cell line platforms, which act like tiny factories to manufacture the large quantity of virus necessary. The live-attenuated virus vaccines are generated by facilitating viral reproduction in cell culture using certain restrictive conditions until they lose their pathogenic properties and are rendered harmless, capable of causing only a mild infection when injected. These live-attenuated vaccines, such as those against smallpox or yellow fever, have proven to be the most effective vaccines ever made and can confer lifelong B-lymphocyte memory. By contrast, non-living vaccines tend to induce protection of much shorter duration and require additional ingredients, or adjuvants (such as aluminium salts), to further stimulate an effective antibody response, as well as booster vaccinations to maintain protective immunity.[4]
Limitations associated with several of these platforms make conventional vaccines less suitable for pandemic production. The urgent demand for large quantities of virus to be grown for global distribution, and the strict level 3 biosafety standards which would need to be maintained to do so (including mandatory use of respirators for all personnel, and sustained unidirectional laboratory air-flow), create significant practical obstacles. And that’s just the manufacturing part. Before live-attenuated viruses can be safely administered to an otherwise healthy population, they need to undergo extensive safety testing to confirm they are free of contaminants, assess for potential side-effects, and ensure they don’t revert to an active (wild type) infection. As well, if virus-like particle vaccines are to be developed in a timely fashion, particularly on a global scale, then several recombinant proteins would need to be simultaneously produced, increasing the manufacturing costs substantially.[5]
What’s Different about the Next Generation Vaccines?
The next generation vaccines, as they are referenced, obviate many of these logistical barriers, and are among the most promising vaccine contenders for the novel COVID-19 virus, or Severe Acute Respiratory Syndrome Coronavirus 2 (abbreviated, SARS-CoV-2). These differ from conventional vaccines in that they include the genetic material needed to induce an immune response. So, rather than presenting pathogen antigens to our immune system, these innovative vaccine strategies contain the blueprint that encodes for an identified protein antigen, and cause our own cellular machinery to produce this immune-stimulating target.[6] It’s a bit like skipping Skip-the-Dishes delivery from your local restaurant, and instead, following the restaurant’s recipe to make your own meal at home, using your own ingredients. The end results are reasonably similar (unless I’m doing the cooking), but several time-intensive steps get bypassed.
The genetic material in these vaccines can be either double-stranded DNA (deoxyribonucleic acid) or single-stranded RNA (ribonucleic acid), and gets delivered to host cells either by way of lipid nanoparticle carrier molecules (genetic vaccines) or via attenuated viruses (viral vector vaccines). Once the genetic material gains access to a host cell, it commandeers the cellular machinery to produce the target antigen protein and have it displayed on the cell surface, in the hopes of activating the immune system and inciting a protective immune response. Some viral vector vaccines are designed to retain the capacity to replicate, or have copies of themselves made, and so are termed replication competent. It’s a bit like the making of a sci-fi thriller, except without the ‘-fi’. Such vectors mimic a regular infection and are able to produce more viral vectors able to infect more host cells, with the potential of inducing more of a protective immune response.[7] Similar to conventional vaccines, then, these next generation vaccines also work by making use of our body’s elegant machinery and natural defense mechanisms, they just do so to a greater extent.
The main advantage of these next-generation vaccines over their conventional counterparts is that they can be developed based on genetic sequence information alone.[8] There’s no need to culture and grow a virus, as in conventional vaccine development, avoiding potential contaminants apt to cause allergic responses. And unlike working with the live-attenuated or inactivated vaccine platforms, there’s no handling of infectious materials by the researchers – they simply need to work with the genetic information sequence to develop the vaccine. As a result, when China announced that a novel coronavirus had been identified as the cause of the Wuhan outbreak, and the genetic sequence was posted on the public database, the development of next generation vaccines were off and running. Building on research done on the other corona viruses – SARS-1 (Severe Adult Respiratory Virus) and MERS (Middle East Respiratory Virus) – investigators were forewarned that the surface spike protein would make for a promising target antigen, further speeding up the process. So, although concerns around the COVID-19 pandemic have certainly fast-tracked the development of these next generation vaccines, they’ve swiftly advanced into clinical trialing primarily because they’re easier to work with, more cost-effective, and faster to develop than conventional platforms.[9]
What are the Side Effects of Vaccines?
Similar to any medical intervention, vaccines have limitations and carry with them the unavoidable potential for side-effects. This is, in part at least, why we shouldn’t put our final hopes in them. In fact, instances of vaccines gone awry and others found to have serious side effects checker the history books of conventional immunization programs. During the polio vaccination of the 1930s, for example, incomplete inactivation of virulent poliomyelitis virus by formaldehyde in the Salk vaccine caused paralysis in large numbers of vaccinated children.[10] During World War II, thousands of US and Allied troops vaccinated against yellow fever developed jaundice due to the presence of hepatitis B in the stabilizing serum of the vaccine.[11] Certain vaccines, such as the smallpox vaccine, have been noted to induce an autoimmune response in susceptible individuals and cause encephalitis. Pertussis vaccines in the past have been associated with causing neurological side effects in children, ranging from transient seizures to serious brain damage and even death.[12]
Although the safety standards have improved considerably since earlier times, these unfortunate events stand as a monument to our limitations, and underscore the importance of rigorous clinical testing and safety analysis for all vaccines. This is particularly the case for novel platforms like the next generation vaccines, which lack a safety track record. Not surprisingly, many are asking if the COVID-19 vaccine will be worth the risk. After all, only one such next generation vaccine to date – directed against the Ebola virus – has received FDA approval. So, while the development of a COVID-19 vaccine may help bring an end to the pandemic and possibly even allow us all to return to some semblance of normality, caution remains essential. Panicked desires to roll out a vaccine using emergency approval measures need to be met with uncompromising safety and efficacy demands. Concerns have already been raised about how early vaccine approval and deployment may compromise the ethical principles of scientific validity, which guide clinical research, and social value, which balances overall risks and benefits.[13] As well, preclinical experience with certain Corona virus vaccines have suggested they may worsen existing lung disease, either directly by producing so-called vaccine-associated enhanced respiratory disease, or as a result of antibody-dependent enhancement as observed in earlier animal models.[14] In addition, the polyethylene glycol (PEG) used in some of the vaccine preparations has the potential to cause antibody-mediated allergic reactions.[15] Furthermore, the spike protein, which has been chosen as the target antigen for the COVID-19 vaccine contenders, resembles a protein essential to human placenta formation, known as syncytin-1.[16] Although this homology doesn’t involve the active binding site of the spike, which many of the vaccines have targeted, some concerns remain that an immune response against the placenta could be triggered, potentially causing infertility in vaccinated women.[17] Since animal reproductive toxicity studies have not been completed, it’s been recommended that pregnant women not receive COVID-19 vaccination in the United Kingdom’s initial roll-out.[18] As well, it’s been advised that pregnancy be excluded for women of childbearing age before vaccination, and that women should avoid becoming pregnant for the first two months after vaccination.
To address these and other issues, more information is needed, information that will take time to carefully gather. In order for questions about long-term efficacy and safety to be properly answered, tried-and-true methodical study is required, and patience on our part is needed.[19] As the apostle Paul admonished, “test everything and hold fast to what is good†(1 Thess. 5:21).
Are Vaccines Ethical?
Both conventional and some of the novel vaccine developments have involved the use of human cell lines derived from aborted preborn babies, raising legitimate ethical concerns. Indeed, how should we, as Christians, reconcile the good of preventing deadly disease with the tragic killing of the innocent? Prayer would be my first response, and confessional prayer, in particular, addressing our complacency as a nation to address this matter of importance. Abortion is considered by many Canadians, Christians included, a non-issue and even defended as a human right. This is shameful. Notwithstanding the Vatican’s statement on vaccines – that in the absence of any alternative, the use of such vaccines are “acceptable if necessary in order to avoid a serious risk not only for one’s own children but also, and perhaps more specifically, for the health conditions of the population as a whole,â€[20] – make no mistake, our holy God will exact vengeance on the slaughterers of the slaughtered. So, whether or not we decide to receive immunization, it’s critical that we, as the body of Christ, support Pro-Life efforts at every opportunity, and get behind lobbying for ethical vaccine development. These efforts can have a positive influence on government policy, as illustrated by the Trump administration’s restriction on the use of human fetal tissue from elective abortions in biomedical research, and prohibition from studies carried out by the National Institutes of Health.[21]
The human cell lines in question are historical lineages. They were derived from abortions dating back to 1962 (WI-38 cell strain), the early 1970s (MRC-5 and HEK 293), and 1985 (PER.C6), and that the abortions were not performed for the purpose of vaccine production. The abortions were wrong, to be sure, but weren’t done in order to make the cell lines. To be clear then, vaccines aren’t “chopped up aborted babies†as some decry. The descendant cells being used in vaccine manufacturing today are not the cells of the aborted child, and never, themselves, formed a part of the victim’s body.
As well, it may also be helpful to understand just how important these cell lines have proved to be for global health. It’s been estimated that vaccines made using the WI-38 cell line, for example, have potentially prevented nearly 11 million deaths and 4.5 billion cases of disease worldwide.[22] Although many vaccines and anti-toxin products have been successfully developed using laboratory animals in the past, logistical issues of cost, contamination, and efficacy have made such approaches less than satisfactory. Research animals require extensive and costly monitoring, and the issue of contamination from other bacteria or viruses remains a threat to safe production. As well, animal-derived vaccines tend to be less effective in producing host immunity. Cultured animal cells may be able to produce the same proteins, but they lack the human-specific surface glycoproteins, or sugar coating, rendering the antigens less able to evoke a reliable immune response. By contrast, vaccines developed from human cell lines have been shown to be more cost effective, have a stronger safety profile, and a higher efficacy.[23]
Should Vaccines be Mandated?
There are two main vaccination strategies used to help bring control to a pandemic and reduce viral-related disease and death. The first is to implement the vaccine with the hopes of achieving so-called herd immunity – that is, vaccinate enough people in the population to confer widespread immunity, with resultant quelling of viral spread and illness. This approach assumes that the vaccine not only protects from serious illness, but also prevents viral shedding and transmission within the population. Different diseases require varying degrees of population immunization to achieve herd immunity. In the case of COVID-19, it’s been estimated that approximately two-thirds of the population would need to receive the vaccination in order to attain this goal.[24] Based on past immunization programs implemented around the world, this significant number of immunizations would likely be unattainable unless vaccinations were compulsory. This is especially the case if a second booster vaccination is required in a timely fashion, and particularly if adverse symptoms like a headache or fever commonly occur.
Mandatory vaccination has certainly proven effective in ensuring high childhood immunization rates in many high-income countries. However, except for influenza vaccination of healthcare workers, and those like myself who do overseas mission work, mandates have not been widely used for adults.[25] Voluntary vaccination programs invariably fall short of widespread uptake. A recent poll found that only 49% of Americans planned to get vaccinated against COVID-19.[26] Even though the fear factor may be high enough in society to keep people masked and socially distanced, vaccine hesitancy remains an issue, and even considered by the World Health Organization to be a major threat to global health.[27] Consequently, many endorse mandatory vaccine implementation. This is certainly the case for the CEO of Australia’s Qantas airlines, who is suggesting that passengers have a “vaccination passport” with proof of COVID-19 vaccination in order to fly.[28] Even Ticketmaster is considering a strategy that would allow individual event organizers to require fans to verify their COVID-19 vaccination status for venue entry, and workplaces could follow suit.[29]
Aside from the logistical nightmare of a mandatory vaccination program, one of the problems with this strategy is that it exposes the entire population, even those at very low risk of significant illness, to the potential side effects of the vaccine. This is a point worth reflecting upon when novel vaccine platforms are being promoted as the “light at the end of tunnel,†to the point where critical long-term safety testing gets bypassed. And of equal concern, this type of draconian implementation infringes upon civil liberties, and places people’s fundamental right to bodily integrity in serious jeopardy.
The other strategy used to reduce viral-related disease and death is to emphasize vaccination for those at highest risk. In the case of COVID-19, this would entail directing vaccination efforts towards the elderly and those with identifiable risk factors for poor outcome, such as heart disease, obesity, and diabetes. One shortcoming of this focussed approach is that two of the important risk groups for developing severe COVID-19 – namely the elderly (>65 years old) and those with obesity (body mass index > 40) – have reduced vaccine efficacy using classical vaccination approaches.[30] Whether the new vaccine platforms will increase immunogenicity in these risk groups compared to classical vaccination approaches remains to be determined. As well, since the safety of the novel COVID-19 vaccines have not been tested in the frail elderly, this exposes them to potential harm, particularly if they are among the first in line to receive the vaccine.
Nonetheless, vaccination that does not annul transmission of virus, but results in protection from severe disease seems much more straightforward and attainable, and is similar to the current practice of recommending seasonal flu vaccine to vulnerable populations. This approach is in keeping with “focused protection†recommendations from the Great Barrington Declaration.[31] Although largely ignored by mainstream media, this document – drafted by a large group of leading infectious disease epidemiologists and public health scientists and endorsed by over 50,000 professional signatories – raised concerns as to the collateral damages of the pandemic and called for the priority of protection and care to be given to at-risk individuals, rather than having a full society lockdown. This approach to vaccination implementation also sits squarely with our Christian worldview, which underscores the importance of caring for the most vulnerable in our society and recognizes people as being made in God’s image with inalienable rights. So, rather than mandating the COVID-19 vaccine, efforts should be focussed on monitoring for long-term side effects, and making sure the vaccine is as effective as possible.
The COVID-19 pandemic is more than a biological insult on humanity. Spiritual forces are at work. As a Christian community then, we need to have the gospel message galvanized in our minds, and join together in fervent prayer. As the apostle Paul clarifies, “our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms. Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand†(Eph. 6:12-13).
[1] Stefan Riedel, “Edward Jenner and the History of Smallpox and Vaccination,†Baylor University Medical Center Proceedings, 18:1, (2005), 22.
[2] Plotkin S. PNAS August 26, 2014 111 (34) 12283-12287; August 18, 2014.
[3] Nabel GJ. Designing tomorrow’s Vaccines. N Engl J Med 2013; 368:551-560.
[4] Mims C.A. The Pathogenesis of Infectious Disease. 2nd Ed. Academic Press Inc., 1982.
[5] Lurie N et al. Developing Covid-19 Vaccines at Pandemic Speed. N Engl J Med 2020; 382:1969-1973.
[6] Lambert LC, Fauci AS. Influenza Vaccines for the Future. N Engl J Med 2010; 363:2036-2044.
[7] van Riel, D., de Wit, E. Next-generation vaccine platforms for COVID-19. Nat. Mater. 19, 810–812 (2020).
[8] Henao-Restrepo, A. M. et al. Lancet 2017; 389, 505–518.
[9] Hacker DL, Wurm, FM. Comprehensive Biotechnology (Second Edition), 2011.
[10] Brodie M, Park WH. “Active immunization against poliomyelitis.†Am J Public Health Nations Health. 1936;26(2):119–125.
[11] Thomas, RE. “Mortality and Morbidity Among Military Personnel and Civilians During the 1930s and World War II From Transmission of Hepatitis During Yellow Fever Vaccination: Systematic Review.†Am J Public Health. 2013 March; 103(3): e16–e29.
[12] Berg, JM. “Neurological Complications of Pertussis Immunization.†Br Med J. 1958 Jul 5; 2(5087): 24–27.
[13] Del-re, R. et al. “Ethical and Scientific Considerations Regarding the Early Approval and Deployment of a COVID-19 Vaccine.†Annals of Internal Medicine; November 2020; https://doi.org/10.7326/M20-7357.
[14] Graham, B. S. Science 368, 945–946 (2020).
[15] Stone CA. “Immediate Hypersensitivity to Polyethylene Glycols and Polysorbates: More Common Than We Have Recognized.†Journal of Allergy and Immunology: In Practice. May 2019; Vol7 (5):1533-40.
[16] Gong R. “Structural characterization of the fusion core in syncytin, envelope protein of human endogenous retrovirus family W. Biochem Biophys Res Commun. 2005 Jun 17; 331(4): 1193–1200.
[17] 2020 News, “Dr. Wodarg and Dr. Yeadon request a stop of all corona vaccination studies and call for co-signing the petition,†accessed December 17, 2020, https://2020news.de/en/dr-wodarg-and-dr-yeadon-request-a-stop-of-all-corona-vaccination-studies-and-call-for-co-signing-the-petition/.
[18] Amy Jones, “Pregnant Women will not Receive Coronavirus Vaccine during Initial Roll-out,†The Telegraph, accessed December 17, 2020, https://www.telegraph.co.uk/news/2020/12/02/pregnant-women-will-not-receive-first-doses-coronavirus-vaccine/.
[19]Del-re, R. et al. “Ethical and Scientific Considerations.â€
[20] “Vatican Statement: Moral Reflections on Vaccines Prepared from Cells Derived from Aborted Human Foetuses,†June 9, 2005. Immunization Action Coalition, accessed December 17, 2020, www.immunize.org/talking-about-vaccines/vaticandocument.htm.
[21] Jocelyn Kaiser and Meredith Wadman, “Trump administration releases details on fetal tissue restrictions,†Science, accessed December 17, 2020, https://www.sciencemag.org/news/2019/07/trump-administration-releases-details-fetal-tissue-restrictions.
[22] Olshansky, S.J., Hayflick, L. (2017). “The role of the WI-38 cell strain in saving lives and reducing morbidity.†AIMS Public Health; 4(2):137-148. Accessed 01/10/2018.
[23] Hegde NR. “Cell culture-based influenza vaccines: A necessary and indispensable investment for the future.†Hum Vaccin Immunother. 2015 May; 11(5): 1223–1234.
[24] Randolph, H. E. & Barreiro, L. B. Immunity 52, 737–741 (2020).
[25] Mello M et al. “Ensuring Uptake of Vaccines against SARS-CoV-2.†N Engl J Med 2020; 383:1296-1299.
[26] Associated Press-NORC Center for Public Affairs Research. Expectations for a COVID-19 vaccine. May 2020.
[27] “Ten Threats to Global Health in 2019,†World Health Organization, last modified 2019, https://www.who.int/news-room/feature-stories/ten-threats-to-global-health-in-2019.
[28] CBC, “International travellers may need COVID-19 vaccines before they can board some airlines,†accessed December 17, 2020, https://www.cbc.ca/news/business/qantas-other-airlines-covid-19-vaccine-proof-1.5813866.
[29] Rachel D’Amore, No Coronavirus Vaccine, no Entry? Experts say it’s Possible in Pandemic’s Next Stage,†Global News, accessed December 17, 2020, https://globalnews.ca/news/7457999/ticketmaster-covid19-vaccine-canada/
[30] Ciabattini, A. et al. Semin. Immunol. 40, 83–94 (2018).
[31] Great Barrington Declaration, accessed December 17, 2020, https://gbdeclaration.org/.