Natural vs. Vaccine-derived Immunity

When the terms “natural immunity” or “naturally-derived immunity” are used, this isn’t in reference to one’s “innate” immune system, but to one’s “adaptive” immune system that has been educated regarding what to attack in the future after being exposed to previous infection(s) – the COVID-19 virus in the case of the current pandemic. God designed the human immune system to remember, learn and improve over time as it fights off more and more invaders – so that it becomes more and more effective with each successful battle. The question that many people have, including doctors and scientists who are trying to fight this pandemic, is if previous infection(s) by COVID-19 produce levels of immunity in people comparable to vaccination? – such as with the modern mRNA vaccines?

Well, the evidence seems reasonably clear at this point, at least to me, that “natural immunity”, derived from a previous COVID-19 infection, is indeed at least as good as the immunity gained from being fully vaccinated via one of the mRNA vaccines (Moderna and even more so vs. Pfizer).

There are several lines of scientific evidence that seem to strongly support this conclusion – particularly since the Delta and Omicron variants of COVID-19 came on the scene.  For example, consider a study published by the CDC in January of 2022, covering a period of time from May 30 to November 13, 2021 (Link).  This study found that those who had survived prior COVID-19 infections were just as protected against serious infections requiring hospitalization as those who were fully vaccinated.

Clearly, the only group of people (among the four groups included in this graph) that is significantly more at risk than the others are those who are unvaccinated and who have had no previous history of a COVID-19 infection. This particular group of people had a much higher risk of serious infection compared to the other three groups of people.

This is consistent with a large Israeli study (covering a period of time from March 1, 2020 to August 14, 2021) that showed that natural immunity is 13 times more effective than vaccination (the Pfizer vaccine in particular) in protecting individuals from future severe COVID-19 infections.

SARS-CoV-2-naïve vaccinees had a 13.06-fold (95% CI, 8.08 to 21.11) increased risk for breakthrough infection with the Delta variant compared to those previously infected, when the first event (infection or vaccination) occurred during January and February of 2021. The increased risk was significant (P<0.001) for symptomatic disease as well. When allowing the infection to occur at any time before vaccination (from March 2020 to February 2021), evidence of waning natural immunity was demonstrated, though SARS-CoV-2 naïve vaccinees had a 5.96-fold (95% CI, 4.85 to 7.33) increased risk for breakthrough infection and a 7.13-fold (95% CI, 5.51 to 9.21) increased risk for symptomatic disease. SARS-CoV-2-naïve vaccinees were also at a greater risk for COVID-19-related-hospitalizations compared to those that were previously infected. (Sivan Gazit, et al., August 2021)

Now, there are those who argue that even though natural immunity may be stronger and even more long-lasting than vaccine-derived immunity against COVID-19, that the vaccine-derived immunity is more consistent.  While this may be true to at least some degree, it doesn’t seem to be all that significant – at least not based on the weight of evidence that is currently in hand as best as I can tell. Smaller CDC studies, for example, that appear to show greater and longer-lasting benefits for the vaccines vs. naturally-derived immunity don’t seem to effectively counter the data described above.

And, I’m not the only one who sees the data this way. For instance, Dr. Marty Makary, a professor at Johns Hopkins University School of Medicine and editor in chief of MedPage Today, argues that mandating vaccines for “every living, walking American” is, as of now, not well-supported by science. He also interprets the current data as showing strong support for natural immunity. He cites over 15 different studies along these lines showing that natural immunity seems to provide even better protection against future severe COVID-19 infections than the vaccines – and therefore should be acknowledged by public health officials (Link).

This is not to say that natural immunity makes the vaccines against COVID-19 irrelevant or useless.  That’s not what this data is saying at all.  Clearly, for those who haven’t yet been infected, getting vaccinated before exposure to COVID-19 is far far less risky, for every age category, compared to getting infected by COVID-19. Just to highlight this reality, note that the Intensive Care National Audit & Research Centre, or ICNARC, just updated their analysis of COVID patients who required critical care in England, Wales and Northern Ireland from May through December of 2021. On this chart, they now show boosted patients as well. They are shown in green. Yes, they are on the chart. You have to squint (Link).


However, for those who have already gone through a COVID-19 infection, vaccinated or not, the resulting immunity derived from that infection should be recognized as being at least equivalent, if not better, to getting vaccinated – over an equivalent span of time.

This is why some countries, including the member states of the European Union, are starting to treat documented recovery from COVID-19 as functionally the same as vaccination in their “vaccine passport” systems (Link).

Still, vaccine-induced immunity is a better choice, not because it produces a stronger immunity, but because it enables you to get the immunity without the side effects and risks that come along with illness — like a greater risk of stillbirth if you’re pregnant, or long COVID, hospitalization and death in general. (Koerth, Jan. 19, 2022)

What this also suggests is that the current surge of the Omicron variant of COVID-19, being far more infectious than any prior variant (while thankfully being less severe than the Delta Variant), might end up as a form of default vaccination, like it or not, for everyone that it infects.  This suggests that the Omicron variant may be the means to ending the entire pandemic – which would be a blessing in disguise. I’m hopeful anyway…

So, in summary, if you haven’t already had COVID-19, get vaccinated. While Omicron is less severe than Delta, it is still making many sick enough to require hospitalization and, right now, more than 3,000 people are being killed by Omicron every day – with many more suffering long-term, even permanent, injuries.  However, if you have already had COVID-19, you probably don’t need to get vaccinated, at least not from a scientific perspective. Personally, though, I would consider getting a booster shot after 6 months to a year.  Now, for those who with naturally-derived immunity who might still need to get a vaccine earlier than this (for political reasons or to travel or for any other reason beyond the scientific evidence itself) I would personally recommend getting the lowest dose available – which is the Pfizer vaccine with its 30 µg dose per vaccination (as compared to the 100 µg dose for the first two Moderna vaccines and the 50 µg Moderna booster). As a silver lining, those who have been previously infected by COVID-19 and who then get at least one mRNA vaccine, end up with the highest levels of immunity against future infections. For me personally, if I had been infected before having a chance to be vaccinated, I would still choose to get at least one Pfizer vaccine – just to be sure.  Fortunately, I was able to get fully vaccinated, and boosted, without having to risk the actual infection itself with a completely naïve immune system.



Bio of Dr. Sean Pitman


Dr. Sean Pitman is a pathologist, with subspecialties in anatomic, clinical, and hematopathology, currently working in N. California. He’s also a life-long Seventh-day Adventist, the son of a retired SDA minister, and is very active in his local church.

6 thoughts on “Natural vs. Vaccine-derived Immunity

  1. I really appreciated reading your article and insight. My concern is the mandate and what it means to healthcare providers and their jobs should they not get the booster vaccine at this time. Is it appropriate to mandate the booster vaccine? And how can one get exempt from it if not wanting to receive it right now? What to do if experiencing “long Covid” after receiving the vaccine? Is that even possible?


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    • I’m biased here since I’m a physician myself. While I personally do not favor vaccine mandates for the general public since I think that they are largely counterproductive, I personally feel that medical providers are in a different category and that medical providers (like doctors and nurses and nursing home workers) should be required to be vaccinated since they deal directly with those who are sick and most vulnerable to serious infection. Timely boosters should also be required for medical personnel since boosters have clearly been shown to improve immunity after 6 months since the previous vaccine was given.

      As far as “Long-COVID”, it is a real risk following a COVID-19 infection, but isn’t a risk following vaccination. The vaccines have not been associated with the symptoms of Long-COVID since vaccines are not based on the use of a live virus that invades the entire body. In fact, there are some research studies that suggest that many Long-COVID cases are likely related to persistent COVID-19 infections (Link). This is probably why many of those who have Long-COVID improve following vaccination.


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  4. The most recent arguments I’m seeing list places like the UK National Statistics where the death rate appears higher for the vaccinated vs. the unvaccinated. Would you have current study links to the efficacy of COVID vaccinations in the U.S. or elsewhere?


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    • Toby Rogers is a political economist who is also strongly anti-vax. He is not a medical scientist or physician.

      In any case, this particular article, by Rogers, distorts the data regarding vaccines and the position of Dr. Peter Aaby – who is a strong supporter of vaccines in general (although, when it comes to COVID-19 vaccines, he seems to favor the adenovirus-based vaccines, such as Johnson and Johnson, AstraZeneca/Oxford or the one produced by China’s CanSino Biologics, over the mRNA-based vaccines – since the adenovirus-based vaccines may have more benefit on reducing “overall mortality – Link). Note, however, that this study found that of the 31 deaths that occured in mRNA-vaccinated individuals, only two were from COVID-19. The rest were due to other causes. For the adenovirus-vaccinated group, two of the 16 deaths were from COVID-19. It’s very difficult, then, to determine a clear relationship here between the different types of vaccines and deaths not related to COVID-19.

      “The study isn’t about the effectiveness of mRNA vaccines against COVID,” said Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health and Security. “The study is aimed to determine if COVID vaccines have non-specific mortality impacts that extend beyond the incontrovertible mortality benefit they confer with COVID-19. Certain vaccines have effects that extend beyond the target infection and decrease mortality from other causes (e.g. measles vaccine).”

      Dr. Monica Gandhi, an infectious disease specialist at the University of California, San Francisco, also said the question of the paper isn’t about COVID-19, but whether the vaccines had a beneficial effect on other causes of mortality. The research reinforced that both types of vaccines significantly prevented COVID-19 deaths, “which is not surprising as both types of vaccines generate cellular immunity against SARS-CoV-2, protecting us against severe disease.”

      “However, to be fair,” Gandhi said, “the number of non-COVID and COVID deaths were rare in all of the pooled analyses and the causes of non-COVID deaths not well adjudicated, so this analysis needs to be taken as preliminary and hypothesis generating at best.”


      What’s interesting here is that studies have shown that the “all cause” mortality rate is also reduced for those who have been vaccinated against COVID-19 – to include those who’ve been vaccinated via the mRNA-based vaccines (Link).

      Anyway, here’s a more balanced view of Dr. Aaby’s position on vaccines (Link). Note also that Dr. Aaby supported the vaccines against COVID-19 for adults (Link), but not necessarily for children since children have significantly reduced risk (compared to adults) for COVID-19 infections (Link). Dr. Aaby did publish some interesting results, however, suggesting that the polio vaccine, as well as the BCG and MMR vaccines, may also reduce childhood risk from COVID-19 as well (Link, Link).

      “We would not be surprised if MMR could provide some protection against severe COVID-19,” said researcher Peter Aaby, of Bandim Health Project in Guinea-Bissau and Research Centre for Vitamins and Vaccines (CVIVA), Statens Serum Institut, a governmental public health and research institution under the Danish Ministry of Health in Copenhagen, Denmark and a pioneer in the field. “Together with my partner Dr. Christine Stabell Benn, we’ve been reporting on mortality reductions from live-attenuated vaccines such as polio, BCG and measles vaccine/MMR for multiple decades now, and arguing for optimized vaccine schedules. With the COVID-19 crisis adding urgency, it’s good to see the potential of non-specific immune effects being taken seriously.” (Link)

      Overall, I do find Dr. Aaby’s main concern to be well-supported that vaccines may produce unforseen beneficial as well as detrimental side effects. In the case of COVID-19, however, it was very clear to me that the potential unknown risks were clearly outweighed when compared to the known risks of getting infected by COVID-19 as well as the very clear known benefits of being vaccinated – particularly for adults over the age of 50 and those with various medical conditions that put them at great risk. Even healthy children seemed to be far more at risk from a live COVID-19 infection than from the vaccines – particularly regarding long-term effects. Of course, this was all before the current less severe Omicron variant took over and the predominant variant worldwide. At this current point in time, vaccines against COVID-19 don’t seem to me to have as significant of an advantage compared to earlier on in the pandemic.

      Hope this helps,



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