Infection was 65% more protective against COVID hospitalization than triple-dose ...
... when the triple-dose was in those never infected
COVID infections ran high in the California prison system, especially among the staff. But naturally-acquired infection was 79% effective at preventing COVID hospitalization against Omicron, while those tripled-dosed but never infected only got 48% protection:
[click on image above to enlarge it]
At bottom right you can see the lower bound and upper bound of 90% confidence intervals around the hospitalization rates. The two-dose primary series failed to reach statistical signficance but naturally-acquired infection did. Three doses and no infection was borderline significant.
Why 90% confidence intervals instead of 95%?
The overlap of 90% confidence intervals is significant at alpha=0.05, even when the standard error on one rate is up to 5 times as large as the standard error on the other. Only when the ratio of standard errors exceeds 5 do you need higher confidence than 90% in order to retain an alpha=0.05 chance of overlap.
The average weekly COVID hospitalization post-vaccine in 2021 was almost 17 per 100,000 person-weeks, and only those who had naturally-acquired infection were solidly below that average.
None of the never-infected had hospitalization rates significantly below the average COVID hospitalization rate of the last half of 2021 — regardless of how many injections they took — but the “infected-but-never-injected” had hospitalization rates significantly below the average of late 2021.
To be fair, the “infected-and-triple-injected” had the lowest-recorded hospitalization rates, but head-to-head comparison against the “infected-but-never-injected” failed to reach statistical significance.
The upshot is, if you want protection against COVID hospitalization, do not rely on the injectable products to achieve it. Even the booster shots were unable to have a vaccine effectiveness of 50% against hospitalization — an industry standard cutoff value for vaccine products.
WHO, for all of its faults, has — or at least had — a 70% vaccine effectiveness standard. Only naturally-acquired infection (alone or with injections) was able to surpass the WHO standard for effectiveness here.
Reference
[California prison study showing protection against COVID hospitalization] — Protection against Omicron from Vaccination and Previous Infection in a Prison System. https://www.nejm.org/doi/full/10.1056/NEJMoa2207082
[average weekly COVID hospitalization was 12.9 per 100,000 in 2020 and 16.9 in 2021] — OWID. https://ourworldindata.org/grapher/weekly-hospital-admissions-covid-per-million
[WHO once recommended 70% vaccine efficacy (VE) against COVID] — Ssentongo P, Ssentongo AE, Voleti N, Groff D, Sun A, Ba DM, Nunez J, Parent LJ, Chinchilli VM, Paules CI. SARS-CoV-2 vaccine effectiveness against infection, symptomatic and severe COVID-19: a systematic review and meta-analysis. BMC Infect Dis. 2022 May 7;22(1):439. doi: 10.1186/s12879-022-07418-y. PMID: 35525973; PMCID: PMC9077344. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9077344/
Quote:
A pooled VE of 90% at five months post-vaccination remains well above the WHO’s preferred estimate of 70% and minimal estimate of 50% when considering effectiveness against the outcome of severe disease [7].