One and Done – Not with Omicron!
Preprint data from South Africa suggests that natural immunity may not be as protective as with prior variants.
A preprint paper posted 01 Dec 2021 on MedRxiv has quickly analyzed routine surveillance data from South Africa with a focus on SARS-CoV-2 re-infections. While not yet peer-reviewed, this represents the most current available data concerning the ability of different viral strains (including Delta and Omicron) to re-infect previously infected patients, and so directly addresses the central question concerning naturally acquired immunity; “Am I protected from new infections if I have already been infected before?” The analysis suggests that, in contrast to Beta and Delta variants, the Omicron variant of SARS-CoV-2 is able to evade immunity from prior infection and re-infect patients at a significant rate. The authors specifically conclude that Omicron’s “selection advantage is at least partially driven by an increased ability to infect previously infected individuals” while acknowledging that “ whether or not Omicron can also evade vaccine derived immunity has important implications for public health globally”.
Increased Risk of SARS-CoV-2 Reinfection Associated with Emergence of the Omicron Variant in South Africa
medRxiv preprint doi: https://doi.org/10.1101/2021.11.11.21266068; published 12/01/21 (1)
The data were drawn from 2,796,982 cases collected between 04 March 2020 and 27 November 2021 using South Africa’s official National Notifiable Medical Conditions Surveillance System. Reinfections were defined as being individuals reported to have sequential positive SARS-CoV-2 tests at least 90 days apart. The authors used two different epidemiologic models to interpret the data, with the primary outcome measuring incidence of suspected reinfections through time as the endpoint for both analyses.
There are at least two major gaps in the analyses. Unfortunately, this retrospective study of epidemiological surveillance data does not provide any insights into the robustness of vaccine-induced immunity against Omicron. It is not clear whether there were sufficient data to assess this outcome and the authors chose to avoid the issue, or perhaps the generally low rate of vaccination in South Africa just did not provide enough cases involving vaccinated individuals to support statistical analysis. The study also does not report any data on infection severity.
Many other reports are indicating that Omicron is associated with generally mild disease compared to prior variants, but the authors did not capture or analyze data relating to disease severity. It is reasonable to speculate that if Omicron can escape natural immunity, it is also likely to have substantial escape potential against vaccine induced immunity. The fact that the original four index cases from Botswana travelers were all fully vaccinated, and the recent reports of an Omicron “superspreader” event where at least half of the 120 fully vaccinated attendees at a Norwegian Christmas party became infected may have been infected from an index case who had recently returned from South Africa suggests that Omicron is both highly infectious and readily able to escape vaccine-induced immunity (2).
So, the question remains whether immunity from prior infection or vaccine induced immunity will reduce transmissibility and provide some level of protection against severe disease and death with the Omicron variant.
Unfortunately, with the emergence of the highly mutated and highly transmissible Omicron variant, enthusiasm about the prospect of achieving herd immunity via either vaccination with Spike genetic vaccines or with the natural immunity provided by prior infection and recovery with earlier variants must be sharply tempered. Furthermore, predictions of emergence of evolved vaccine escape mutant viruses by many well-qualified virologists and vaccine experts including myself unfortunately appear to be coming to pass.
Fortunately, unlike with Marek’s disease, vaccination into an ongoing viral pandemic does not seem to have yielded a strain that causes enhanced disease – yet (3). Let’s hope that does not occur, although it remains a risk if the WHO and national health authorities continue to insist on deploying mismatched leaky vaccines that clearly do not prevent infection and spread of current circulating strains of SARS-CoV-2. The logic of vaccine mandates using these flawed tools is clearly failing – current vaccines and aggressive mask use policies cannot stop the spread of the highly infectious Omicron variant.
Furthermore, recent data from Hong Kong demonstrating clinical myocarditis in 1 out of every 2700 boys who receive the second Pfizer/BioNTech Comirnaty dose (4), together with a report from Viet Nam of over 120 students being hospitalized after receiving the same vaccine (5) make it clear that mandating that children be vaccinated with these ineffective vaccines is quite literally medical malpractice, and may meet legal criteria as a crime against humanity.
Conclusions from the paper:
Our analyses suggest that the cumulative number of reinfections observed through the end of wave 3 was consistent with the null model of no change in reinfection risk through time. Furthermore, our findings suggest that the relative hazard of reinfection versus primary infection has decreased with each subsequent wave of infections through September 2021, as would be expected if the risk of primary infection increased without a corresponding increase in reinfection risk. Based on these analyses, we conclude there was no population-level evidence of immune escape associated with emergence of the Beta or Delta variants.
We find evidence of a substantial and ongoing increase in the risk of reinfection that is temporally consistent with the timing of the emergence of the Omicron variant in South Africa, suggesting that its selection advantage is at least partially driven by an increased ability to infect previously infected individuals.
In contrast, we find no evidence that reinfection risk increased as a result of the emergence of Beta or Delta variants, suggesting that the selective advantage that allowed these variants to spread derived primarily from increased transmissibility, rather than immune escape.
Immune escape from prior infection, whether or not Omicron can also evade vaccine derived immunity, has important implications for public health globally. Quantifying the extent of Omicron’s immune escape for both natural and vaccine- derived immunity, as well as its transmissibility relative to other variants and impact on disease severity are urgent priorities to inform facility readiness planning and other public health operations.