Another non-peer-reviewed preprint article about natural immunity versus vaccines for COVID-19 is being used as the “gotcha” moment for the anti-vaxxers. And on the surface, the article might be interesting, but it’s being misused. What a shocker.
I’m going to do a quick review of the article, then remind everyone why vaccinations are ALWAYS better than natural immunity. Outcomes from diseases that are prevented by the vaccine must be weighed against the safety and effectiveness of that vaccine. This is a necessary risk-benefit analysis that is required by every procedure or pharmaceutical in evidence-based medicine. And, this is the point that is missed by those pushing this new preprint.
Natural immunity vs. vaccine COVID-19 preprint
In a paper posted on the preprint server medRxiv, researchers conducted a retrospective observational study comparing three groups in Israel:
- SARS-CoV-2-naïve individuals who received a two-dose regimen of the Pfizer mRNA vaccine,
- previously infected individuals who have not been vaccinated, and
- previously infected and single dose vaccinated individuals.
The first analysis compared two groups – Pfizer-vaccinated individuals against previously infected individuals. The researchers put 16,215 individuals in each group, matched to reduce confounders. Their analysis of the two groups found the following:
- For individuals who were either vaccinated or contracted COVID-19 during January and February 2021, there were 238 breakthrough infections with the vaccinated group versus 19 in the previously infected group. This is a 13X greater risk for SARS-CoV-2infection in the vaccinated group.
- For individuals who were either vaccinated or contracted COVID-19 at any time from March 2020 through February 2021, the researchers showed waning of antural immunity. The vaccinated group had a nearly 6X greater risk for a breakthrough infection and a 7X increased risk for symptomatic disease.
But this isn’t the whole story. For example, buried in the charts shows that the risk for getting COVID-19 is about 0.5X (or half the risk) for those who were previously infected and vaccinated compared to the group that was previously infected. Professor Christina Pagel describes this succinctly in her Twitter review:
I’m deeply troubled that the authors didn’t discuss this point in their abstract. But there’s more.
But there’s a glaring omission – they provide no odds ratios between the vaccinated group and those who are not vaccinated. Of course, this study didn’t appear to do that statistical analysis, they obviously had access to the data.
There are also several statistical and bias issues that might make these results even less dramatic than they appear. A researcher, Dr. Diego Bassani, PhD, provided a clear critique of some of the analyses that are laid out better than I could write here:
Dr. Bassani lays out more issues with the analysis in the Twitter thread, which really makes me think that the differences in risk are much less than is described in the paper. That is why these papers need to be peer-reviewed – we’re doing it by Twitter now, which means most people, except those with scientific expertise, are reading the peer-review, and most others accept these preprints at face value.
Weighing risk and benefit
Although I would agree that maybe immunity from natural infections is better than COVID-19 vaccines (or maybe any vaccine), this ignores the singular purpose of the vaccine – to prevent infection in the first place.
To get a natural infection, one must be infected with the pathogen. And that has consequences:
- From 4 April to 20 June, unvaccinated people died from COVID-19 at 16.6X the rate among the fully vaccinated.
- Before 20 June, admissions of unvaccinated people with COVID-19 to hospital were running at 13.3X the rate among the vaccinated.
- Unvaccinated people were infected at 11.1X the rate of the vaccinated before 20 June.
Even if we accept the hypothesis that those with natural immunity to COVID-19 are less likely to get a breakthrough infection than vaccinated individuals, the unvaccinated have a much greater risk of infection, hospitalization, and death than those who are vaccinated.
We eradicated smallpox through a worldwide vaccination program (something we might never see again). Natural infection with smallpox probably produced a more robust immune response for life than the vaccine. Unfortunately, up to 30% of those who got the disease died (and a much larger number of babies).
This argument is made with all vaccines by anti-vaxxers. That’s why some anti-vaxxers think that getting their children infected by chickenpox and measles – they ignore the fact that there is a small, but statistically significant risk that those children when infected will need to be hospitalized or die.
This new Israeli study may provide evidence that the natural immunity from a COVID-19 infection is better than the immunity from vaccines. But it overlooks or intentionally ignores two key points:
- Natural infection plus previous COVID-19 infection is better than natural immunity or vaccines alone.
- And vaccination is substantially better than getting the infection, which carries a much higher risk of hospitalization and death.
These kinds of studies annoy me so much. They make a comparison between two groups that is intellectually interesting, but it ignores the whole reason to get vaccinated – so you don’t have to endure the risks of the disease.
This is another article that should be ignored.
- Scobie HM, Johnson AG, Suthar AB, Severson R, Alden NB, Balter S, Bertolino D, Blythe D, Brady S, Cadwell B, Cheng I, Davidson S, Delgadillo J, Devinney K, Duchin J, Duwell M, Fisher R, Fleischauer A, Grant A, Griffin J, Haddix M, Hand J, Hanson M, Hawkins E, Herlihy RK, Hicks L, Holtzman C, Hoskins M, Hyun J, Kaur R, Kay M, Kidrowski H, Kim C, Komatsu K, Kugeler K, Lewis M, Lyons BC, Lyons S, Lynfield R, McCaffrey K, McMullen C, Milroy L, Meyer S, Nolen L, Patel MR, Pogosjans S, Reese HE, Saupe A, Sell J, Sokol T, Sosin D, Stanislawski E, Stevens K, Vest H, White K, Wilson E, MacNeil A, Ritchey MD, Silk BJ. Monitoring Incidence of COVID-19 Cases, Hospitalizations, and Deaths, by Vaccination Status – 13 U.S. Jurisdictions, April 4-July 17, 2021. MMWR Morb Mortal Wkly Rep. 2021 Sep 17;70(37):1284-1290. doi: 10.15585/mmwr.mm7037e1. PMID: 34529637.
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