No point vaccinating those who’ve had COVID-19: Cleveland Clinic study suggests

Scientists from the Cleveland Clinic, USA, have recently evaluated the effectiveness of coronavirus disease 2019 COVID-19) vaccination among individuals with or without a history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

The study findings reveal that individuals with previous SARS-CoV-2 infection do not get additional benefits from vaccination, indicating that COVID-19 vaccines should be prioritized to individuals without prior infection. The study is currently available on the medRxiv* preprint server (not peer-reviewed).

Study: Necessity of COVID-19 vaccination in previously infected individuals. Image Credit: Orpheus FX / Shutterstock
Study: Necessity of COVID-19 vaccination in previously infected individuals. Image Credit: Orpheus FX / Shutterstock

Background

In the United States, the US Food and Drug Administration (FDA) has provided emergency use authorization for two mRNA-based COVID-19 vaccines developed by Pfizer/BioNTech and Moderna, which have shown high efficacy against SARS-CoV-2 infection and COVID-19 disease in clinical trials. However, the ability to vaccinate a large part of the global population is limited by vaccine supply.

In order to ensure fair access to vaccines throughout the world, the COVID-19 vaccines Global Access (COVAX) initiative was launched. In many countries, especially those with low socioeconomic status, there is a serious shortage of vaccines. Thus, in order to get the maximum vaccine benefits, the most vulnerable population should be prioritized for the vaccination.

Currently, most countries prioritize vaccination for healthcare and other frontline workers, elderly people, and people with comorbidities.

To further narrow down the prioritization criteria, the scientists in the current study have evaluated the necessity of COVID-19 vaccines for individuals who were previously infected with SARS-CoV-2.

Study design

The study was conducted on 52,238 employees in the Cleveland Clinic. A positive RT-PCR test was considered to define SARS-CoV-2 infection. The participants received two doses of the Pfizer/BioNTech or Moderna COVID-19 vaccine at an interval of 28 days. A participant was considered vaccinated after 14 days of receiving the 2nd vaccine dose. Similarly, a participant who tested positive for SARS-CoV-2 at least 42 days before the vaccination initiation was considered previously infected.

Explanation of “previously infected” analyzed as a time-independent covariate and “vaccinated” treated as a time-dependent covariate.

Explanation of “previously infected” analyzed as a time-independent covariate and “vaccinated” treated as a time-dependent covariate.

Important observations

Of all enrolled participants, 5% had previous SARS-CoV-2 infection. Compared to 59% of non-infected participants, only 47% of previously infected participants were vaccinated by the end of the study. About 63% of all vaccinated participants received the Moderna vaccine.

The analysis of cumulative COVID-19 incidence revealed that during the course of the study, SARS-CoV-2 infection occurred almost exclusively in participants who were not previously infected and were not vaccinated.

Interestingly, no significant difference in COVID-19 incidence was observed between previously infected and currently unvaccinated participants, previously infected and currently vaccinated participants, and previously uninfected and currently vaccinated participants.

The participants from these three groups exhibited a significantly lower incidence of SARS-CoV-2 infection compared to previously uninfected and currently unvaccinated participants.

Specifically, of all infections during the study period, 99.3% occurred in participants who were not infected previously and remained unvaccinated. In contrast, only 0.7% of infections occurred in participants who were not previously infected but were currently vaccinated.

Importantly, not a single incidence of SARS-CoV-2 infection was observed in previously infected participants with or without vaccination.

Simon-Makuch plot showing the cumulative incidence of COVID-19 among subjects previously infected and not previously infected with COVID-19, who did and did not receive the vaccine. Curves for the unvaccinated are based on data for those who did not receive the vaccine during the duration of the study, and for those waiting to receive the vaccine. Day zero was Dec 16, 2020, the day vaccination was started in our institution. Error bars represent 95% confidence intervals. Seven subjects who had been vaccinated earlier as participants in clinical trials were considered vaccinated throughout the duration of the study. Twelve subjects who received their first dose in the first week of the vaccination campaign managed to get their second dose three weeks later, and were thus considered vaccinated earlier than 42 days since the start of the vaccination campaign
Simon-Makuch plot showing the cumulative incidence of COVID-19 among subjects previously infected and not previously infected with COVID-19, who did and did not receive the vaccine. Curves for the unvaccinated are based on data for those who did not receive the vaccine during the duration of the study, and for those waiting to receive the vaccine. Day zero was Dec 16, 2020, the day vaccination was started in our institution. Error bars represent 95% confidence intervals. Seven subjects who had been vaccinated earlier as participants in clinical trials were considered vaccinated throughout the duration of the study. Twelve subjects who received their first dose in the first week of the vaccination campaign managed to get their second dose three weeks later, and were thus considered vaccinated earlier than 42 days since the start of the vaccination campaign

With further statistical analysis, it was observed that the COVID-19 vaccination significantly reduced the risk of SARS-CoV-2 infection in previously uninfected participants but not in previously infected participants.

Although the study did not directly estimate the duration of protection from natural infection, it was observed that previously infected participants remained protected against COVID-19 for at least 10 months after the symptom onset or a positive test result.

Study significance

The scarcity of vaccines, coupled with the knowledge that vaccines do not provide additional protection to those who have already been infected, is the strongest argument for restricting vaccine administration to those who have not had the infection.

In addition to the profession, age, and comorbid conditions,  previous infection should be an important consideration in deciding whom to prioritize to receive the vaccine.

A practical and useful message would be to consider symptomatic COVID-19 to be as good as having received a vaccine, and that people who have had COVID-19 confirmed by a reliable laboratory test do not need the vaccine.

The study concludes, "individuals who have laboratory-confirmed symptomatic SARS-CoV-2 infection are unlikely to benefit from COVID-19 vaccination, and vaccines can be safely prioritized to those who have not been infected before."

In contrast, individuals without prior SARS-CoV-2 infection can get the maximum benefits from vaccination. Thus, based on the study findings, COVID-19 vaccines should be prioritized to naïve individuals without a history of SARS-CoV-2 infection.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:
Dr. Sanchari Sinha Dutta

Written by

Dr. Sanchari Sinha Dutta

Dr. Sanchari Sinha Dutta is a science communicator who believes in spreading the power of science in every corner of the world. She has a Bachelor of Science (B.Sc.) degree and a Master's of Science (M.Sc.) in biology and human physiology. Following her Master's degree, Sanchari went on to study a Ph.D. in human physiology. She has authored more than 10 original research articles, all of which have been published in world renowned international journals.

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Comments

  1. Sean R Sean R United States says:

    They FDA hasn’t approved any of the vaccines currently being distributed in the United States. They have granted emergency use but they are still NOT approved by the FDA.

    • Fred Chittenden Fred Chittenden United States says:

      The FDA may not have any regulations or protocols for the new mRNA vaccines.  However, doesn't mean these medications aren't effective at generating immunity to COVID19.  This new technology has the potential to offer all sorts of additional uses the development of the mRNA technology moves forward.  

      What's going on the the burrOcrats are in the multi-year process of attempting to develop a broad and flexible set of regulations and protocols for these new mRNA medicines.  It's not a simple task as the possibilities for use of the technology are significant when it comes to providing treatments and therapies for all sorts of maladies, for groups as well as for individual customized therapies...

      This doesn't mean they are necessarily dangerous or deadly.   Only that the technology is new.  The old FDA vaccine definitions and regulations are like the  MS-DOS computer operating systems, and now Windows has shown up. And, unlike computer science, where the marketplace forces largely guide development, in virology, the marketplace is constrained by the FDA burrOcrat definitions and regulations.  

      A decision had to be made about using, or not using these mRNA therapies to impart immunity to COVID19 for the populations at large rather than to let the ravages of COVID19 pandemic (real or not) and various burrOcrat responses to that pandemic and negative effects of continuing infections to take down businesses, the economy and more...  

      Giving the mRNA therapies emergency approval doesn't mean they are bad vaccine options for most folks.  The demographics of the vaccines use generally hold up as mRNA vaccines are effective for most, but not all, folks..   There efficacy appears to fall within the normal acceptable range of risk reward for large vaccination projects.   Yes, some people will have all sorts of negative reactions to these therapies...  That doesn't mean they are bad therapies.  Only new therapies using technology that the FDA and others are just barely coming to understand...  

      The additional reality, that is finally being reported, is folks who have existing natural immunity to COVID19 from exposure to all sorts of COVID virus attacks, including COVID19, SARS1 (2003) and several other COVID colds and flus.   These many millions of folks DO NOT need to undergo the unnecessary risk of taking the vaccines...  

      Sadly, the research into providing quality antibody tests for the status of one's COVID immunity has been slow in developing quality results.   Some of this is because COVID19 is NOT A NOVEL VIRUS that no one has preexisting immunity to.  It turns out that there's millions and millions of folks all around the world with some degree of natural immunity to COVID19 from exposure to other COVID flus and colds...  

      The NOVEL claim for COVID19 was bogus from the start...  It's was used to incite fear in the masses that everyone was going to die from this unknown flu.  Except, it turns would COVID19 wasn't all that new... Infective yes, but not new.  

      So the question might be asked (or is begging to be asked), why come out with the NOVEL VIRUS claim for COVID19?   Hmm...  Perhaps it was because the virus escaped from a gain of function (weaponized bioweapon) lab in China and they didn't really know much about this weaponized flu virus.  So the powers in charge (aka the WHO -- World Health Organization most run by China) decided to err on the side of caution and made up the NOVEL VIRUS claim for this escaped flu virus that they didn't know that much about...  

      Translation -- EXHIBIT A that COVID19 was a weaponized virus program that got out of control is those in charge knew it was a newly developed and highly infective virus that had escaped. So they pushed the NOVEL panic button...  There is no research anywhere backing up the bogus claim that COVID19 is or was a NOVEL virus.  However, there's a growing body of evidence that there are all sorts of other COVID flus and COLDs that exposure to and recovery from impart some degree of immunity to COVID19.  Most significantly, the SARS1 flu of 2003...  The folks that had and recovered from this flu almost two decades ago are (so far as research can tell) still retain 100% immunity to COVID19...  COVID19 is NOT a new virus -- it's more of a highly infective strain of an existing flu...  And there's now a variety of therapeutics to treat COVID19 infections.   FYI, vaccines can not be used to treat COVID19 infections -- vaccines are NOT therapeutic treatments.  Vaccines are preventive therapies...

      • Steve Barnhaus Steve Barnhaus United States says:

        Your terminology is wrong. "COVID19" could never be a novel virus simply because that's not the name of the virus; that would be SARS-CoV-2 (COVID19 is the disease caused by that virus).

        And flu is flu; it's caused by influenza viruses. Coronaviruses only cause conditions that we would consider part of the "common cold" set.

        Regardless, SARS-CoV-2 *does* have some novelty. No cold viruses, and very few flu variants, have had such a high degree of lethality. Although about 600,000 deaths have been officially attributed to COVID19 in the U.S., we've had 920,000 more people die in the past 18 months than would be expected from statistical trends. Most of those must be COVID19-related.

  2. Algonquin Loon Algonquin Loon United States says:

    Thnk you to Dr. Dutta for confirming what many of us already knew. There were so many articles recommending the vaccine to Covid survivors citing the fact that the antibody production was significantly higher felt like Marketing.. an advertisement without due clarification. Of course there will! Our bodies are primed for war.

    This whole experience has been been very frustrating. Everything from nearly useless mask wearing, that transitioned from not recommended to mandatory with totally inadequate justification. I've been around long enough and possess biochemical/medical background such that I knew the directives were coming from an odd angle. This article sets me at ease in a 'told you so' sort of way.

  3. Douglas Collins Douglas Collins United States says:

    There is an error in this article. None of the covid vaccines are currently "approved" by the FDA as the writer says. They are authorized for emergency use, not approved. In fact, public health agencies are legally prohibited from claiming that they are "approved" though some agencies are illegally doing so. The process for approval would normally take till at least 2023, I believe, and at least until now is still unfinished.

  4. Alexander Kaffka Alexander Kaffka Georgia says:

    "COVID-19 vaccines should be prioritized to naïve individuals without a history of SARS-CoV-2 infection".  Just love those editors!

  5. Hmm
    Al R Al R United States says:

    You are inserting your own opinion with "there is no point..." In the title. The study does not say that AND as a physician I would hope you know that a single study does not always tell the entire story. It's fine if this is the case, but to say there is no point is a step further than this study indicates.

  6. Duane Kerzic Duane Kerzic United States says:

    Anyone that actually reads the study will see at no point did the authors say there is no point in getting vaccinated. They said you could safely prioritize those who have not been infected before which is something very different from saying there is no point in vaccinating those that have already had covid.

    I totally agree those that haven't had disease should be PRIORITIZED for vaccination if there is a shortage of available vaccine. At least for a period of up to the 7-8 months post-disease this study covers.

    However I don't agree that there is no point in those that have had disease not getting vaccinated where there is sufficient vaccine and certainly post 12 months after disease.

    And this study totally supports what I just said. But id does not support there is no point in getting vaccinated if you have had covid as the author implies. So how this is going to be spread around and become fodder for the antivaxxers.

    • Chubakka Richardson Chubakka Richardson United States says:

      Sir, this statement VERIFIES what people with 'common sense' have been preaching since the invention of this political hot potato- "A practical and useful message would be to consider symptomatic COVID-19 to be as good as having received a vaccine, and that people who have had COVID-19 confirmed by a reliable laboratory test do not need the vaccine." AND, your messiah Fauci's OWN email to constituents actually stating that uninfected mask wearing does NOTHING to prevent the spread of the virus to that mask wearer!!!

      • Duane Kerzic Duane Kerzic United States says:

        This is not what the study said. It's what one person said after reading it. It doesn't not reflect common sense to anyone that actually is a virologist. And the 'study' only followed people for a period of 5 months. Maybe you need to learn to read?

        And Fauci's email was written early in the pandemic. And at that time it was not known that covid spread asymptomatically. There has never been a respiratory virus that spread asymptomatically know to exist before this one. So there goes your 'common sense'.

        And it has been proven time and again that wearing a mask reduces the reproduction constant. But that's probably above your education level to be able to understand.

        • DeLaun Fifield DeLaun Fifield United States says:

          Maybe it is YOU who needs a little lesson in permeability. So lets begin. How can a filter that is 700 times larger than the particle STOP the particle? Covid 19 is .0125 microns in size, the holes in the mask are .700 microns in size-or roughly 600 times LARGER than Covid! So please explain to me, "the uneducated" how a mask can do ANYTHING to stop Covid 19 transmission??

          • Samrod Shenassa Samrod Shenassa United States says:

            "Covid 19 is .0125 microns in size"

            The diameter of the SARS-Cov-2 virus that causes COVID-19 is about 0.1µm in diameter.

            "the holes in the mask are .700 microns in size"

            Holes in woven face masks are even larger, between 5µm to 200µm, yet still keep the 0.1µm virus from passing thru. There are additional factors that must be considered.

            • When we shed virus, we're actually shedding packets of water that contain particles of SARS-Cov-2. These packets-- called aerosols when under 5µm in size, and just droplets when larger-- are far larger than whatever virus they may be carrying.

            • While the gaps between actual fibers are larger than the virus particle, the fibers are wider than the gaps, and have smaller fibers protruding from them in various directions like a vine.

            • At the microscopic level, traveling thru the gaps is less like passing thru a chain linked fence and more like drunk flying through a long tunnel with thick bushes and shrubs growing off the walls.

            • Traveling randomly in all directions rather that straight lines, aerosols have a high rate of impacting with fibers or the many offshoots. This is called diffusion.

            • Finally, masks usually have multiple layers of protection insuring that exponentially fewer particles make it thru each successive barrier.

            I hope knowing the mechanics at the microscopic level clarifies how masks offer so much protection despite having gaps so much larger than the virus particles.

      • Duane Kerzic Duane Kerzic United States says:

        In the past all respiratory viruses were symptomatic before the infected person could spread them. The infected person has a fever, congestion, cough or other symptoms. So it was easy to isolate the infected and break the chain of transmission. There are many ways to do this. And it's why in some places, like healthcare setting you are asked those questions and your temperature it taken before you're allowed to enter.

        But with SARS-CoV2 it is more infectious before the infected have any symptoms. So there is no way to isolate people that have it before they can infect others.

        So when Fauci wrote that email it was still assumed we'd be able to isolate those with symptoms and control outbreaks. However it was confirmed about 30 days after that email was written that SARS-CoV2 spreads asymptomatically. And later it was confirmed that it was less infectious after symptoms appeared. And then it was confirmed that it was actually the immune system response following infection that was what was really effecting people.

        So at that point it became important for everyone to wear even simple masks. Because they greatly reduced the asymptomatic spread of SARS-CoV2. Because they stopped the infected person from giving it to someone else. But yeah, freedumbs and all of that.

        But yeah, I get that people not capable of thinking for themselves would find that hard to understand. They just follow along whatever some authority figure in their lives tells them and claim they are thinking for themselves.

        • Stephen Campbell Stephen Campbell Canada says:

          That last paragraph is gold considering that you are preaching the msm narrative, so who’s really thinking for themselves

        • Jonny Fin Jonny Fin United States says:

          Here is a meta-analysis of 54 studies including 77k participants on household spread (so masks aren’t a factor) that illustrates asymptotic spread is virtually non existent.

          Results  A total of 54 relevant studies with 77 758 participants reporting household secondary transmission were identified. Estimated household secondary attack rate was 16.6% (95% CI, 14.0%-19.3%), higher than secondary attack rates for SARS-CoV (7.5%; 95% CI, 4.8%-10.7%) and MERS-CoV (4.7%; 95% CI, 0.9%-10.7%). Household secondary attack rates were increased from symptomatic index cases (18.0%; 95% CI, 14.2%-22.1%) than from asymptomatic index cases (0.7%; 95% CI, 0%-4.9%), to adult contacts (28.3%; 95% CI, 20.2%-37.1%) than to child contacts (16.8%; 95% CI, 12.3%-21.7%), to spouses (37.8%; 95% CI, 25.8%-50.5%) than to other family contacts (17.8%; 95% CI, 11.7%-24.8%), and in households with 1 contact (41.5%; 95% CI, 31.7%-51.7%) than in households with 3 or more contacts (22.8%; 95% CI, 13.6%-33.5%).

          jamanetwork.com/.../2774102

    • Jody Lanham Jody Lanham United States says:

      there is no need to get vaccinated if previously infected.  data has been showing that natural immunity from previous infection is strong.  this is not new information, and this being the case is more than likely to continue to prevail.  why would any common sense individual or entity suggest otherwise, and waste a vaccine on someone who does not need it.  Kind of like carrying an umbrella around during a rainstorm while inside a building, you are already protected from getting wet why would you need the extra protection????

  7. Mike D Mike D United States says:

    "All of the participants were employees of Cleveland Clinic."  
    It seems unlikely that the employees of one of the best health clinics in the world reflect the behaviors of the general public.  Also, the US was still largely in a period of reduced social interaction (aka 'lock down').  There was no ability to track exposures.  Also, unlike Europe and Africa, the US (especially Ohio) had a minimal incidence of the other strains of this virus.  

    All this adds up to a very weak study if one wants to assess the risk in the general society under normal conditions.

  8. Peter Zorin Peter Zorin United States says:

    Sorry, but your article creates false narrative.

    scitechdaily.com/.../

  9. Laurie Pierce Laurie Pierce United States says:

    In addition to the aforementioned comments, I am not seeing the statistical modeling, which was used in this study.  While this is a nascent area of study, there was no review of current literature.  There is also no shortage of vaccination and we are struggling to get late adopters to accept vaccination in general.  It is also too early to state how long natural immunity will continue.  Finally, the COVID vaccinations appear to be reducing the effects experienced by, "long haulers."  www.yalemedicine.org/news/vaccines-long-covid.  The author will have a difficult time getting this through peer review.

    • Duane Kerzic Duane Kerzic United States says:

      Exactly. If this was India or Brazil right now, or another country with a shortage of vaccine this is an important consideration. Give the vaccine doses to those that have not had infection first. And maybe only give one dose so everyone has some protection.

      But this is getting spread on every department of health website in the USA right now and increasing vaccine hesitancy. And we need to get everyone vaccinated if we want a normal life again.

    • Jonny Fin Jonny Fin United States says:

      It’s great to have a non-experimental option too!

    • Brett Whaley Brett Whaley United States says:

      A recent study from Washington University of St Louis SOM took bone marrow aspirations and found that long term immunity in the previously infected is highly likely. Antibodies do not stick around forever. The task eventually goes to long term memory cells in the bone marrow that produce resistance in the future when re-exposed to the pathogen.

      We know through common sense that the previously infected have at least approximately 18 months of immunity as they are extremely rarely reinfected. Those that are have minimal issues.

      We do NOT know the same for the vaccinated as the genetic therapies have only been in mass circulation for 6-7 months.

      It is also interesting that we in the medical community ignore the worldwide studies on therapies such as Ivermectin that have shown great success in TREATMENT.

  10. Jonny Fin Jonny Fin United States says:

    Because of this I don’t seek out interventions from them unless it’s absolutely necessary. So coming from this angle I find it odd that people are even assuming the man made intervention would somehow be superior to nature. The onus is on the human intervention to prove it’s worth.

  11. Brett Whaley Brett Whaley United States says:

    It would seem many of my health care colleagues do not want anything to make it to publication that opposes their personal, often unsubstantiated and proven incorrect, viewpoints. That is not science. This result reinforces what we have known about immunity for decades, at least. Medical amnesia that has occurred for the past year and a half should be the next big study.

    Multiple studies, even going as far as testing bone marrow for long term immunity, have been conducted and show the same. They contradict the narrative but, again, are in line with medical history. They are far more likely to be correct.

  12. steve schneider steve schneider United States says:

    You're going about this backwards, as if you are just reiterating sentiment from CNN.  How about: until scientific research/study proves that immunity from prior COVID infection has a short lifespan, a vaccine is NOT necessary for those with prior infection? You can't have it both ways in the "follow the science" debate, which is soooo clearly skewed by politicians and Main Stream Media.

    I am NOT injecting a foreign concoction into my body to fight a virus my body has naturally defended itself against 20 months ago: especially when reinfection data/study (like this) states it's unnecessary and the long term affects of the vaccine are obviously untested.  If you are going to make the argument that I, and all prior infected people, need to take the vaccine because it has a positive health/science implication then please attach a link to the study that argues the point.

    Love the lack of philosophically backwards train of thought among those advocating for mass vaccinations.

  13. Carla Sabotta Carla Sabotta United States says:

    It would be useful to know if in this study there was any impact of existing co-morbidities on the effectiveness of natural immunity as compared to vaccine-induced immunity.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.