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Home » Vaccine mandates for those with previous COVID infection – policy debate

Vaccine mandates for those with previous COVID infection – policy debate

This article about vaccine mandates for anyone with a previous COVID-19 infection was written by Dorit Rubinstein Reiss, Professor of Law at the University of California Hastings College of the Law (San Francisco, CA), who is a frequent contributor to this and many other blogs, providing in-depth, and intellectually stimulating, articles about vaccines, medical issues, social policy, and the law.

Professor Reiss writes extensively in law journals about the social and legal policies of vaccination. Additionally, Reiss is also a member of the Parent Advisory Board of Voices for Vaccines, a parent-led organization that supports and advocates for on-time vaccination and the reduction of vaccine-preventable disease. She is also a member of the Vaccines Working Group on Ethics and Policy.

In this post, I set out the debates around allowing those with a previous COVID-19 infection to be exempt from U.S. vaccine mandates. 

A quick reminder– the virus is SARS-CoV-2, while the infection with the virus causes the disease, COVID-19 (or just COVID). 

The policy takeaway point is that while, in my view, the choice to allow those with a previous COVID infection an exemption from vaccine mandates can be reasonable, the choice not to allow an exemption also has very good policy reasons behind it.

Since it is a valid policy choice, mandates without such an exemption cannot, in my view, be legally challenged. Those wanting their institution to exempt them because of natural immunity need to convince their institution to do so, and if the institution refuses, do not have viable legal recourse. Under our current law – rightly – in uncertainty, the policymakers have the flexibility to choose the option they think is safer.

I am not a scientist, and I think this is an area of substantial scientific uncertainty. But I have to start by setting out some background, and I will try to summarize what I think we do and do not know.

I will add that my thoughts on this have developed. When I came into this topic, I thought a previous infection should be grounds for exemption. Now, I think there’s an argument both ways, and in fact, the argument against an exemption for the previously infected is stronger – though an institution would still be on solid grounds if it chose to give one, for policy reasons.   

a sick man wiping his nose with tissue
Photo by cottonbro on

Immunity after infection with SARS-CoV-2

Again, there is substantial uncertainty, simply because COVID-19 is new. Previously identified coronaviruses do not confer life-long immunity. It is still uncertain how long immunity after infection with SARS-CoV-2 will last. But there are recent studies suggesting immunity could be long-term.

We do not yet know how long that means, though. And many of the early patients were infected with either the original variant or the Alpha variant, not the Delta variant now dominant in the US. It appears the disease-derived immunity is substantially less against the delta variant. In any case, there can be reinfection.  

Further, the study only evaluated symptomatic patients. So we do not know whether patients who tested positive but were not symptomatic, have significant levels of protection against reinfection with SARS-CoV-2. 

Still, the general result –  a previous infection may offer protection as good as vaccination to many people – reflects what other studies show.

We also do not quite know how long protection from vaccines against COVID-19 generally and the delta variant specifically would last. We know the vaccines offer good protection against hospitalizations and deaths from Delta even six months or more after full immunization.

We also have several studies suggesting that vaccinating the previously infected benefit from revaccinating – they get a substantial boost to their immunity.

While studies suggest that previously infected have stronger unpleasant temporary reactions to the vaccines, there is nothing suggesting they are at higher risk of the rare, serious side effects from the vaccines – and a day of discomfort, while unpleasant, is not actually an argument against vaccinating.

On this background, the CDC recommends that previously infected be vaccinated.

Policy Options:

  1. Giving vaccine mandates exemptions to those with proof of previous COVID-19 infection
  2. Requiring those with proof of previous infection to satisfy the mandate with one dose of vaccine
  3. No exemptions: Requiring full vaccination from all. 

In this article, I’m only addressing the first and third alternatives, although the second is a valid policy option – for the same reasons against one, not one that should be required from policymakers. 

Photo by Nataliya Vaitkevich on

Argument for giving an exemption to those with previous infection

There are three arguments for giving an exemption to vaccine mandates to anyone with a previous COVID-19 infection. Each has validity, but there are counterarguments. Note that Israel, for example, accepted the previous infection as a substitute to vaccinating in its mandate; it is a legitimate option, in my view. 

First, fairness. The argument is that while the previous infection may provide imperfect protection, so do vaccines. If we accept the imperfect protection from vaccines for a mandate, we should accept the previous infection – it may be as or more protective. 

It’s unfair to discriminate based on the source of the imperfect protection. This argument is valid, but it is less strong, however, if the focus is on minimizing infection now, which would likely be better served by requiring the previously infected to get at least one dose. And if you’re looking at burden, the infected already “paid their dues” by getting the disease – which for many would be at least as burdensome as being vaccinated.

Second, reducing resistance. The argument is that a mandate would generate less resistance and be easier to apply if it is more narrowly tailored. Mandates actually work better and easier if there is widespread voluntary compliance, and giving a break to the previously infected may make the mandate more broadly palatable and, in the end, help it work better. This is certainly somewhat speculative, but it’s a reasonable argument. 

Third, resource-conserving. Vaccine supply is not unlimited, and mandating vaccines for the previously infected, if they’re less likely to get COVID-19 again, would mean fewer vaccines available, for example, for booster doses for the immune-compromised or for the developing world. This is a valid argument, too, but it is less strong when there is no shortage of vaccines. 

In short, there are valid reasons for giving an exemption to vaccine mandates to individuals with a previous COVID-19 infection.

Note that one reason that is not convincing is a comparison to vaccines for, say, measles or chickenpox, where the previous infection is accepted as a substitute. For those vaccines, there is strong evidence that in the vast majority of people, previous infection provides robust, life-long immunity. We are just not there yet for disease-derived immunity after infection with SARS-CoV-2. 

Arguments against vaccine mandates exemption for those with a previously COVID-19 infection

Here, too, there are three top arguments. 

First, implementation challenges. There are multiple challenges in implementing an exemption to the previously infected, and many institutions may see these challenges as making this a non-starter. First, not all previous infections are the same. A positive COVID-19 test in the past is not the same as being hospitalized from COVID-19 in terms of substituting for vaccines, and drawing the line can be tricky.

Institutions can require specific testing to address this, but that adds a burden, and it’s not clear it’s reasonable to demand from institutions. I am not even sure there is a clear test to address this. The CDC says:

Antibody tests currently authorized under an EUA have variable sensitivity, specificity, as well as positive and negative predictive values, and are not authorized for the assessment of immune response in vaccinated people. Furthermore, the serologic correlates of protection have not been established, and antibody testing does not evaluate the cellular immune response, which may also play a role in vaccine-mediated protection.

Further, confirming a previous infection, absent hospitalization, can be tricky in other ways. For some diseases, institutions would accept a doctor certificate – but we already know that there are doctors willing, for example, to write fake medical exemptions from masks, and given the politicization of the pandemic, there is a very real risk of widespread abuse there. Testing, again, can be used, but it’s not clear we have a good test here – and it’s not clear it’s reasonable to require an institution to accept testing in conditions of uncertainty.

Second, safety from disease concerns. While the previous infection can provide protection, there are still a lot of uncertainties. And there is strong evidence that vaccinating after infection provides robust protection. For the goal of preventing COVID-19 and harms, requiring vaccines after reinfection is a reasonable measure. It can increase disease prevention at very low risk. 

Third, perverse incentives. A very real risk is that accepting the previous infection will encourage people to seek out and try to get infected against COVID-19. We really do not want people to go looking for COVID-19. It can lead to deaths, harm, and more disease rather than less.

For these reasons, not providing an exemption is a reasonable option, too. 

COVID-19 infection vaccine mandates
Photo by Ann H on


There are reasonable grounds to give an exemption to the previously infected, but there are also very reasonable grounds not to do that. Given that, policymakers should have leeway to choose the better option for their institution, and right now, that is where the law is very likely to end.

Dorit Rubinstein Reiss

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