The risk of Omicron infection increases dramatically with the number of vaccine doses, by up to 300% for three or more doses, a study has found, in one the most striking illustrations of negative vaccine efficacy yet to emerge.
The study, which is not yet peer-reviewed, gathered data on infection rates among employees of Cleveland Clinic in Ohio from September 12th to December 12th 2022. The primary aim was to study the effectiveness of the new bivalent COVID-19 vaccine, which it found to be just 30% effective against infection during the study period.
A secondary aim was to look at the effectiveness of earlier doses, and the results were, the researchers say, “unexpected”. There was an “increased risk of COVID-19 with higher numbers of prior vaccine doses”, as illustrated starkly in the cumulative incidence plot below. Those who had three or more doses were around three times or 300% as likely to have a Covid infection than the unvaccinated. This is negative vaccine efficacy of minus-200%.
The authors address possible alternative explanations for the worrying results, but say they don’t think they account for what they see.
A simplistic explanation might be that those who received more doses were more likely to be individuals at higher risk of COVID-19. A small proportion of individuals may have fit this description. However, the majority of subjects in this study were generally young individuals and all were eligible to have received at least three doses of vaccine by the study start date, and which they had every opportunity to do. Therefore, those who received fewer than three doses (over 45% of individuals in the study) were not those ineligible to receive the vaccine, but those who chose not to follow the CDC’s recommendations on remaining updated with COVID-19 vaccination, and one could reasonably expect these individuals to have been more likely to have exhibited higher risk-taking behavior. Despite this, their risk of acquiring COVID-19 was lower than those who received a larger number of prior vaccine doses.
The dose-dependence of the effect would also seem to be a huge giveaway.
The authors note that “this is not the only study to find a possible association with more prior vaccine doses and higher risk of COVID-19” and draw the conclusion: “It is important to examine whether multiple vaccine doses given over time may not be having the beneficial effect that is generally assumed.”
This is not the only study to find a possible association with more prior vaccine doses and higher risk of COVID-19. A large study found that those who had an Omicron variant infection after previously receiving three doses of vaccine had a higher risk of reinfection than those who had an Omicron variant infection after previously receiving two doses of vaccine. Another study found that receipt of two or three doses of a mRNA vaccine following prior COVID-19 was associated with a higher risk of reinfection than receipt of a single dose. We still have a lot to learn about protection from COVID-19 vaccination, and in addition to a vaccine’s effectiveness it is important to examine whether multiple vaccine doses given over time may not be having the beneficial effect that is generally assumed.
Results like these naturally demolish any notion that vaccines protect other people and thus any rationale for mandates, which some places, particularly in the U.S., continue to impose.
Unlike the vaccines, natural immunity is effective at preventing infection, the study finds – though less and less with each new variant and as time passes, as might be expected.