In other words, I’m saying….

  1. Naturally acquired immunity to COVID-19 has been proven superior to that from mRNA vaccines in laboratory and clinical studies
  2. Vaccine induced immunity wanes over time, whereas naturally acquired immunity remains robust for significantly longer
  3. Official data confirm that large numbers and percentages of vaccinated persons can still become hospitalised and die
  4. Data analysis is complicated by manipulation of statistics and definitions of “vaccinated” and “unvaccinated”
  5. Vaccination in the already naturally immune has significant risks and likely has limited short term benefit

Claim 3: The immune response to natural infection from measles is stronger than from vaccines

NH: “Early in the presentation, Dr Canaday claims natural infection can provide a stronger immune response than vaccines, at least in measles.”

DrPC: I have addressed the matter of natural immunity to measles and the occurrence of measles disease in vaccinated subjects in response to claim #11.

NH: “Dr Campbell said the evidence when it comes to COVID-19 vaccines points the other way, directing Newshub to research in the UK which found “for most people vaccination against COVID-19 will induce more effective and longer lasting immunity than that induced by natural infection with the virus”, and it was recommended to get vaccinated even after infections “because it will boost whatever immunity you have from natural infection”. There is also US research suggesting mRNA vaccines are better at defending against variants like Delta than infection with prior strains of the SARS-CoV-2 virus.”

Vaccine-induced antibodies are more targeted to the binding sites on the spike protein (sites the virus uses to latch onto target cells) than those induced by natural infection,” said Dr Campbell.”

DrPC: I am loathe to argue with my esteemed former colleague in training at the University of North Carolina, and now Director of the National Institutes of Health, Dr Francis Collins, whose news blog is quoted above. The suggestion that vaccine-induced antibodies may be able to recognise and bind to the receptor binding domain (RBD) of SARS-CoV-2 variants with single-letter mutations better than naturally acquired antibodies is compelling. (However, this addresses only simple and limited ones, and does not account for more than single letter mutations or successive mutations, as in the current Delta strain).

The protection provided by systemic, whole-body spike protein RBD antibodies to SARS-CoV-2 by mRNA vaccination contrasts with that where the body naturally produces antibodies at the portal of entry of the virus, the nose and upper respiratory tract, and thus vaccine-induced protection may be a bit less compelling.  There is also a suggestion that the Delta variant may be poised to acquire complete resistance to the wild-type spike protein vaccines in current use. (R1)

Robust response where the virus enters may well dispatch the invader effectively before it reaches the lungs and circulatory system, where large volume replicating virus and the body’s more profound and sometimes overactive immune response can occur, and indeed some vaccines in development do target the nasal route. (R2) 

Whereas the current COVID-19 vaccines delivered intramuscularly target the spike protein, the robust and multiplex components of the immune system can recognise nucleocapsid and a host of other protein epitopes of the virus and not only produce antibodies to multiple target sites, but also engage the cellular defenders, such as T-cells, B-cells, monocytes, and other components of the rich and complex natural immune system with which we have been gifted. 

So, why the emphasis only on vaccine-induced antibodies to the spike protein, where the natural immune system provides a much broader and arguably more nuanced response, and where concerns like antibody-dependent enhancement following vaccination are not a significant concern?

NH: “Dr Petousis-Harris said there were several diseases for which vaccines provide better protection than infection, without having to experience the disease itself. There is also research showing measles can wipe out the immune system’s memory of other infections, further discouraging relying on natural infection.”

DrPC: Here we are with measles again. Yes, this matter of decreased immune system memory for other infections after naturally acquired measles disease is a significant consideration, although one would also want to investigate whether such suppression occurs after measles vaccination as well. I am not aware of such studies, but that is not the subject of this response. COVID-19 is not measles, so let’s talk about COVID-19 and the vaccines directed against SARS-CoV-2, shall we?


There is now an abundance of studies to suggest that natural immunity is superior to vaccine-induced immunity, in response to SARS-CoV-2. (R3, R4). A report from the Cleveland Clinic of 1359 infected health care workers noted that not one of them was reinfected 10 months into the pandemic, despite high exposure to COVID-19 patients. (R5) Studies in recovered patients also showed durable and broad immunity after natural infection when considered alone (R6), or when compared to vaccinated subjects, and also show a more durable and broader spectrum of immunity. (R7)

More robust immune response in the nasopharynx in natural infection compared to vaccination was also demonstrated, consistent with my contention above. (R8) Decay of antibody titres in the vaccinated was much more apparent than in the post-convalescent patients in Israel. (R9) These and over a dozen more such studies can be found in a Rapid Response letter by Paul Alexander to the British Medical Journal (R10), including one showing a highly functional virus-specific cellular immune response in asymptomatic infected individuals. (R11

As a former treating respiratory and critical care physician, I believe we must pay more attention to the clinical results in actual practice than the laboratory findings.


In my opinion, the most significant recent study on naturally acquired immunity vs vaccine-induced immunity comes from a recent study from Israel. (R12) While this is a pre-print study, as many COVID-19 published literature is these days, it draws upon a huge data base where a large majority have completed the 2-dose Pfizer regimen, and where every citizen is enrolled in a regional health care entity where data can be reliably interrogated.

Three groups were studied: those vaccinated compared to those who acquired COVID-19 disease during the same time that the vaccine rollout began (January and February 2021); those who acquired COVID-19 disease at any time from March 2020 compared to those vaccinated at the time that the vaccine rollout began (January and February 2021); and those who acquired COVID-19 disease at any time compared to those who had acquired COVID-19 disease at any time, and also received a single dose of the Pfizer vaccine during initial rollout.

Confounding factors of age, sex, metropolitan area as a proxy for socio-economic status and various chronic diseases and co-morbid conditions were minimised through the usual statistical techniques. 

In the first group, the vaccinated subjects had 13 times the risk of breakthrough infection and 27 times the risk of symptomatic breakthrough infection compared to the naturally immune subjects who acquired disease whilst the other subjects were vaccinated (16,215 subjects in each group). There was an 8-fold increase in hospitalisations in the vaccinated subjects.

In the second group, despite the waning of natural immunity with time, the vaccinated subjects still had 6 times the risk of breakthrough infection and 7 times the risk of symptomatic breakthrough infection compared to the naturally immune subjects who acquired disease at any time (46,035 subjects in each group). There was also a 5-fold increase in hospitalisations in the vaccinated subjects.

In the third group, COVID-19 subjects with a single dose Pfizer vaccination had one-half the risk of breakthrough infection and 0.7 times the risk of symptomatic breakthrough infection compared to the naturally immune subjects who acquired disease at any time (14,029 subjects in each group). There was one hospitalisation in a naturally immune, non-vaccinated subject. These results in total however did not reach statistical significance when considering only the 82% of subjects where the vaccination was given after a positive PCR test. Only age >60 and lower socioeconomic status were independently associated with poorer outcome.

So, what did we learn? In a closely studied population where the Delta variant has been predominant, naturally acquired COVID-19 infection confers superior immunity when compared to that of individuals completing vaccination during the same time, and the results remain similar although less marked even when naturally acquired immunity weakens somewhat with passage of time. Benefit extends to evidence of infection (as measured by a positive RT-PCR test), symptomatic infection and hospitalisation. Single dose vaccination in a group with prior infection may confer a modest but not statistically significant additional protection compared to those with natural immunity alone.


We have seen from the above that protection remains among the COVID-19 convalescent subjects (who recovered from prior disease), despite the passage of time. The Israeli Health Ministry has also noted decreased efficacy in Pfizer vaccine against infection with the now-prevalent Delta variant. Indeed, whereas its efficacy was 95% in May, it fell to 64% on 6 June and 39% on 17 July. It now falls below the 50% threshold set by the WHO for acceptable vaccine efficacy. (R13) That said, the Ministry considers that the two-dose regimen still protects against serious illness and hospitalisations at 88-91% reduction (R14), but does it?

As of September 2021, 78% of those over 12 years old had been fully vaccinated. A recent news story by Dr. Kobi Haviv, one of Israel’s prominent respiratory physicians, told that some 85-90% of hospital patients and 95% of seriously ill patients are the “fully vaccinated,” and indeed Israel now has one of the highest infection rates in the world (R15). Note that this is an opinion based on frontline clinical experience and is not reflected in Israeli Ministry of Health statistics:


Findings from an outbreak in Barnstable County, Massachusetts in July 2021, where vaccination coverage among eligible residents was 69%, occurred at a rate of 74% among fully vaccinated persons. Four of the five hospitalised had been fully vaccinated, where Delta was the predominant strain (90%). (R15A)

The following UK data were gathered from Public Health England, where the Delta variant has been the dominant strain. (R16, R16A, R16B)  I have used this as a primary source, as Technical Bulletins #20 and #23

UK stats 1 Feb to 12 Sept 2021- from PHE 17 Sep 2021
Delta cases 80%, recent >98%
Age  (Delta cases)# unvax% unvax# 1 vax% 1 vax# full vax% full vax# TOTAL
CASES (ALL AGES)257,35443120,81120157,39827593,572
Since 2 August 2021
HOSP+1,342+77% +252+53% +1,588+205%+3,250

From these figures, we can conclude that:

  1. All unvaccinated persons represented 50% of all persons hospitalised
  2. Most deaths (65%) in persons under 50 were in the unvaccinated
  3. Whilst nearly two-thirds of deaths in those under 50 were in the unvaccinated, this group represented less than 4% of all those <50 who were hospitalized
  4. Whilst the total number of persons in hospital was 25% greater for those under 50, there were over 11x the number of deaths in the over 50 age group compared to the under age 50 age group
  5. Nevertheless, despite being partially or even fully vaccinated, deaths in the over 50 age group accounted for 73% of all the deaths in their age group and 67% of all deaths that occurred in ALL age groups
  6. Nearly 50% of ALL cases during the entirety of the reporting period were acquired in the last 6 weeks, with the fully vaccinated representing a 235% increase in cases, a 205% increase in hospitalisations and a 301% increase in deaths

My enquiry to the NZ MOH requesting similar statistics, including co-morbidities, confined to the recent outbreak since August, has not yet been answered.


So, what about the United States? We are told that “hospitals are filling up with the unvaccinated!” and that “… unvaccinated adults aged 18 or over are 17 times more likely to be hospitalized compared with vaccinated adults” during the period 1 January to 24 July 2021 (R17-pdf), and that we have a “pandemic of the unvaccinated!” However, the CDC has instructed health care personnel NOT to test vaccinated persons for PCR positivity upon entry to hospital, whereas unvaccinated persons are universally tested before entry, and may have acquired a positive test while there. (R18-pdf) An interesting finding in the study, however, was that there was no difference in admissions to ICU or deaths between the groups, once admitted to hospital. The vaccinated group also spent longer time in intensive care at 5 days compared to 4 days for the unvaccinated.

Updated on 25 August, 2021, the CDC now characterises unvaccinated persons as the following: any who have not received a COVID-19 vaccine, any who have received a first dose of vaccine and up to 21 days afterwards (e.g. Pfizer) AND any who have received a second dose of vaccine until 14 days have since passed. (R19) Thus, any infection occurring during temporarily reduced immune competence immediately following vaccination is not counted as post-vaccination. Adverse effects following the first or second doses of the vaccine are also counted as occurring in an “unvaccinated person,” even though 80% of adverse effects following vaccination occur within the first 2 weeks.  Anything else is considered a “breakthrough case,” although as of 1 May 2021, CDC no longer tracks such cases unless they result in hospitalisation or death. (R20)

Even the vaccinated may not be counted correctly if vaccination occurs at a drive-through clinic, “vax-tent,” pharmacy or other temporary structure as we see also in New Zealand. Even if one is given a ‘vaccination card”, the lot number and notation of a medically trained person may be absent, and results may not be forwarded to become part of the person’s official medical record. A further review of these topics discussed can be found here (R21) and here (R22).


There is increasing concern that vaccinating those who have recovered from COVID-19 disease are at significantly higher risk of complications which would outweigh the modest and short-lived benefit that has been seen with single-dose vaccination of those previously and long-since recovered from COVID-19 disease. (R23) Increased risk of fever, fatigue, myalgia-arthralgia (muscular and joint pain) and lymphadenopathy (swollen lymph glands) were found after Pfizer vaccination in those with prior COVID-19 disease (but not long-COVID). (R24)

Similar findings in another study demonstrated higher incidence of fever, breathlessness, headache, chills, flu-like illness, fatigue and to some extent local reactions (R25), and even higher risk of hospitalisations. (R26) Then there are the known and unknown risks of vaccination itself, including myocarditis, thrombotic events related to circulating synthetic spike protein and auto-immune disease. (R27) Clinical reports of increases in “unmasked” cancers and viral diseases such as herpes zoster post-vaccination may also change the risk-benefit analysis. (R28)


Natural immunity of those previously infected with COVID-19 has been proven largely superior or at least equal to vaccine-induced immunity in laboratory studies as well as in clinical ones.  A single dose of a dual dose regimen, as with the Pfizer product, appears to offer a small, temporary boost in immune response and perhaps a clinically apparent reduction in risk of developing COVID-19 as determined by a positive PCR test. It also appears, at least for now, that the vaccines may provide a modest advantage in reducing hospitalisations and deaths during the current era where the Delta variant is prevalent.

There remain considerable questions about the reliability of publicly available clinical data however, and there does not appear to be support for the narrative that we are now seeing a “pandemic of the unvaccinated” when significant numbers of patients, even when officially acknowledged, have been fully vaccinated. It remains to be seen whether we will soon observe a “pandemic of the vaccinated,” if accurate statistics concerning who is vaccinated and who in unvaccinated can be obtained.

So, for New Zealanders who haven’t had COVID-19 and been able to develop natural immunity (most or all of us), what can we do? But hang on, are some New Zealanders already immune because they have experienced COVID-19?  I have heard multiple personal stories of those who had gotten “really sick” towards the end of 2019 and early 2020 who did not seek medical attention. Testing for antibody evidence of prior SARS-CoV-2 infection for the individual patient has been outlawed in NZ, as has importation of testing kits. (R28A) Such test kits may only be used upon direction of public health and DHB authorities. But even that does not test for the widespread background T-cell immunity that many people have. I will address this topic in my response to Claim #10.

Perhaps we’ll never know if there is a significant reserve of background natural immunity. Treatment alternatives to universal vaccination have also been systematically suppressed; this topic will be taken up in my response to Claim #24.

For further reading on the topics raised above, go here (R29) and here (R30). A focused review on the topic by a guest author is provided here. (R31)


R1: SARS-CoV-2 Delta variant is poised to acquire complete resistance to wild-type spike vaccines.

R2: Intranasal COVID-19 vaccine effective in animal studies.

R3: Discrete Immune Response Signature to SARS-CoV-2 mRNA Vaccination versus Infection.

R4: SARS-CoV-2 infection induces long-lived bone marrow plasma cells in humans.

R5: Necessity of COVID-19 vaccination in previously infected individuals.

R6: Longitudinal analysis shows durable and broad immune memory after SARS-CoV-2 infection with persisting antibody responses and memory B and T cells.

R7: Single cell profiling of T and B cell repertoires following SARS-CoV-2 mRNA vaccine.

R8: mRNA vaccine-induced SARS-CoV2-specific T cells recognize B.1.1.7 and B.1.251 variants but differ in longevity and homing properties depending on prior infection status.

R9: Large-scale study of antibody titer decay following BNT162b2 mRNA vaccine (Pfizer) or SARS-CoV-2 infection.

R10: Vaccinating people who have had COVID-19: why doesn’t natural immunity count in the US?

R11: Highly functional virus-specific cellular immune response in asymptomatic SARS-CoV-2 infection.

R12: Gazit S et al. Comparing SARS-CoV-2 natural immunity to vaccine-induced immunity: reinfections versus breakthrough infections.

R13:  What is COVID-19 vaccine efficacy?

R14: Reduced efficacy with Delta variant, prevents serious illness.

R15: Vaccine effectiveness in Israel among the fully vaccinated.

R15A: Outbreak of SARS-CoV-2 Infections, including breakthrough, in Barnstable County, July 2021.

R16: Statistics regarding hospital admissions and deaths of COVID-19 in UK, from PHE technical briefing12 September 2021. variants of concern and variants under investigation (;   SARS-CoV-2 variants of concern and variants under investigation (

R17: COVID-19-associated hospitalizations among vaccinated and unvaccinated adults.


R19: CDC bulletin, Aug 25, 2021.

R20: COVID-19 Vaccine Breakthrough Infections Reported to CDC.

R21: CDC lists vaccinated deaths as unvaccinated, repost of Dr Joseph Mercola, 15 Sept 2021.

R22: Letter to editor + 26 references.

R23: Differential Effects of the Second SARS-CoV-2 mRNA Vaccine Dose.

R24: Previous COVID-19 infection but not Long-COVID associated with increased adverse events following Pfizer vaccination.

R25: Robust spike antibody responses and increased reactogenicity in seropositive individuals after a single dose of SARS_CoV-2 mRNA vaccine.

R26: Self-reported real-world safety and reactogenicity of COVID-19 vaccines.

R27: Vaccinating people who have had covid-19: why doesn’t natural immunity count in the US? BMJ 2021; 374.

R28: Pathologist Dr Ryan Cole on increased cancers and viral diseases post vaccination.

R28A: Medsafe outlaws Point-of-Care COVID-19 tst kits with fines or imprisonment if breached.

R29: Natural immunity vs COVID-19 vaccine-induced immunity- Marc Giradot of PANDA.

R30: COVID-19 natural immunity compared to vaccine-induced immunity: The definitive summary.

R31: Guest column on the value of naturally acquired immunity.