A recent peer-reviewed study conducted in Austria suggests that a fourth dose of the COVID-19 vaccine may not be as effective as anticipated. The retrospective population-based observational study utilized national health data and compared outcomes among individuals who received four vaccine doses with those who received fewer doses or no vaccinations.
The study, published in the European Journal of Clinical Investigation, covered the period from Nov. 1 to Dec. 31, 2022, involving 3,986,312 individuals. Surprisingly, the relative vaccine efficacy for the fourth dose was negative 24 percent compared to those who received three doses, indicating more COVID-19 deaths among those with four doses.
Furthermore, an extended observation period through June 30 revealed that individuals with four doses had a 17 percent reduced risk initially, but this benefit waned over time, leading to a higher risk of infection compared to less vaccinated individuals. The study also highlighted a potential “healthy vaccinee bias,” suggesting that individuals with better health, who are more likely to be vaccinated, might skew efficacy claims.
The findings raise questions about the justification for repeated vaccine boosters for the general population with a history of previous infections. The study emphasizes the need for careful consideration and reevaluation of current recommendations regarding additional COVID-19 vaccine doses