Lesson 8 — What's Contested? What Don't We Know?
How Do Vaccines Actually Work?
Learning Material
1 pagesLesson 8 — What's Contested? What Don't We Know?
Understanding the Complex: How Do Vaccines Actually Work?
Vaccines are among the most studied medical interventions in history, and the scientific evidence for their safety and efficacy in preventing specific diseases is, for most major vaccines, overwhelming. But "vaccines work" is a scientific statement, not a policy prescription — and the questions that follow from it are genuine, contested, and often value-laden. This lesson takes four of those questions seriously.
1. Why do people hesitate to vaccinate?
Vaccine hesitancy — the WHO identified it as one of the ten biggest threats to global health in 2019 — is not a single phenomenon. It is a collection of overlapping concerns with different causes, histories, and demographics. Treating it as simple ignorance or irrationality has repeatedly failed as a public health strategy.
Some hesitancy is rooted in historical experience. The Tuskegee Syphilis Study — in which the US government withheld treatment from Black men with syphilis for forty years, from 1932 to 1972, in order to study disease progression — remains one of the most significant reasons for medical distrust among African Americans. This is not irrational; it is a calibrated response to documented institutional betrayal. Similar experiences exist in other countries and communities.
Some hesitancy is driven by genuine uncertainty about specific products. The Johnson & Johnson COVID vaccine was associated with a rare but serious clotting disorder (VITT) — roughly 1 in 500,000 doses — that led regulators in several countries to restrict its use. This was not a failure of vaccine safety systems; it was those systems working correctly. But it also gave people who had asked "what if something is wrong?" a reason to feel their question was legitimate.
Some hesitancy is driven by misinformation spread through social media — false claims about ingredients, mechanisms, or side effects that are demonstrably incorrect. But the presence of misinformation does not invalidate the underlying legitimate concerns, and conflating the two has made communication harder.
Understanding vaccine hesitancy requires engaging with its actual causes — not dismissing it as a deficiency to be corrected.
2. How fast can safety be established? Was eleven months enough?
The COVID vaccines were developed in roughly eleven months. Standard vaccine development takes a decade or more. The question of whether the speed compromised safety is legitimate — and the answer is more nuanced than either "yes, it was rushed" or "no, the same standards applied."
The speed was achieved not by cutting corners but by parallelizing steps that are normally sequential. Clinical trials — which typically run Phase 1, then Phase 2, then Phase 3 in sequence — were run simultaneously. Manufacturing began at risk (spending billions before authorization, accepting that doses might need to be discarded if the vaccine failed) so that supplies would be ready if and when authorization came. Emergency use authorization — as opposed to full approval — allowed deployment before all long-term data were available, with ongoing safety monitoring.
What was genuinely uncertain at authorization was the long-term safety profile — data that cannot be collected quickly by definition. Those data have now been collected, across billions of doses, and the long-term safety profile of the COVID mRNA vaccines is well established. The rare serious side effects (myocarditis, primarily in young males after a second dose) have been characterized; the rates are lower than the myocarditis risk from COVID infection itself.
Those who argued in late 2020 that not enough was known had a point about epistemics that was overtaken by events. Those who argued the vaccines were unsafe had made a claim that subsequent evidence did not support.
3. Should vaccination be mandatory?
This is a genuine value question, and this course will not answer it. What it will do is present the strongest version of each position.
The case for mandates: Infectious disease is a collective action problem. Individual vaccination decisions affect others — particularly those who cannot be vaccinated (infants, immunocompromised individuals) and those for whom vaccines provide incomplete protection. Herd immunity — the threshold at which enough people are immune to interrupt pathogen transmission — requires high vaccination rates. Some communities have historically not reached that threshold voluntarily. Mandates, or significant incentives, may be necessary for truly dangerous diseases.
The case against mandates: Bodily autonomy is a foundational principle in liberal societies and in medical ethics. Informed consent — the idea that patients must voluntarily agree to medical interventions — is not merely a procedural norm; it reflects the view that individuals have rights over their own bodies that cannot be overridden by collective benefit calculations, except in the most extreme circumstances. Mandates may also backfire, increasing resistance rather than compliance.
Democratic societies have reached different conclusions — vaccine requirements for school entry are common, while broader mandates remain contested. Both positions reflect genuine values.
4. Global vaccine equity: who gets access first?
The failure of COVAX described in the previous lesson raises a structural question: is global vaccine equity achievable within the current pharmaceutical system?
The argument for IP waivers — temporarily suspending patent protections on vaccines during pandemics, as South Africa and India proposed to the WTO — is that the technology is largely publicly funded and that manufacturing capacity exists in lower-income countries (notably India) that could be deployed if they had access to the know-how. The argument against is that patents incentivize R&D investment, and waiving them removes incentives for the private investment that accelerated COVID vaccine development.
Both arguments have merit. The resolution — if one is achievable — likely involves neither pure IP protection nor pure waiver, but technology transfer agreements, advance purchase commitments, and international manufacturing investment.
Next lesson: What comes next? — HIV, malaria, RSV, universal flu vaccines, and what the next pandemic response could look like.
Reading time: approx. 10–11 minutes