The Healthy Vaccinee Effect - How Did It Impact COVID-19 Statistics?

A recent study from the Czech Republic has added to our understanding of the impact and effectiveness of COVID-19 vaccines and their relationship with the "healthy vaccinee effect".  

  

The healthy vaccinee effect also known as the healthy vaccine bias is observed when better health among a vaccinated population results in a vaccine appearing to be more effective than it is.  The term was originally applied to influenza vaccine research by Jennifer Nelson in 2005:

 

...which found that the reduction in risk of death from influenza in vaccinated American seniors was related to preferential receipt of the influenza vaccine by relatively healthy seniors.  Here's a quote from the summary of the study:  

 

"In this study, the reductions in risk observed in the before influenza period suggest the presence of bias due to preferential receipt of vaccine by relatively healthy seniors."

Other studies in Canada, Sweden, Germany, Spain and a 40 nation analysis have also researched healthy vaccinee effects for influenza vaccines over the past twenty years. 

  

In the aforementioned Czech Republic study of the COVID-19 vaccines:

...the authors analyzed two data sets from two Czech health insurance companies consisting of a population of approximately 2.2 million people, representing more than one-fifth of the nation's population.  They examined the validity of claims of the healthy vaccinee effect by analyzing the association between all-cause mortality and COVID-19 vaccination status in subjects 60 years of age and older.  Each age group in the study was stratified according to their vaccination status; unvaccinated vs individuals vaccinated less than four weeks vs. more than four weeks from doses 1, 2, 3 and 4 or more doses of a COVID-19 vaccine.

 

When considering the raw data alone, it would appear that there is a higher level of all-cause mortality among the vaccinated seniors aged 60 and older which suggests that vaccination works remarkably well at preventing death.  That said, the authors note that the data shows that of the deaths over the study period, 37,000 of the 269,000 all-cause deaths (14 percent) were COVID-19 related.  In fact, during a low COVID period between June 2021 and September 2021, almost no COVID-related deaths were recorded in the Czech Republic (0.3 percent to be precise) meaning that almost all of the deaths during that period were non-COVID-related.  Here's a quote from the study:

 

"When comparing the two largest groups in that period, i.e., unvaccinated and those with the completed primary course, the unvaccinated population was more than twice as likely to die as the population with the completed primary course. This apparent “vaccine efficacy” in a period when no COVID was present is likely an artifact of the HVE (healthy vaccinated effect).

 

During the high COVID period from October 2021 to May 2021, there were almost 10,000 COVID-19-related deaths.  The vaccine effectiveness in preventing COVID-related deaths should have lead to an increase in the ratio of unvaccinated to vaccinated all-cause mortality.  In fact, the exact opposite happened; the all-cause mortality in the chart with a completed primary course more than doubled compared to the low-COVID period and the all-cause mortality of the unvaccinated chart rose by only one-third.  

 

The authors' conclusions are as follows with my bolds:

 

"The results of the presented analysis revealed several peculiar patterns of the relationship between all-cause mortality and vaccination status. The presented data obviate that vaccination status has a profound association with all-cause mortality, which goes far beyond the possible protective effect against COVID-related death, especially in the low-COVID periods. Using a simple model, we argue that this pattern can be, to a large degree, attributed to the healthy vaccinee effect....

 

...to the best of our knowledge, the presented study provides the best and most robust illustration of the healthy vaccinee effect in COVID-19 vaccination so far. The implications are huge—based on our results, we propose that the evaluation of the baseline frailty between vaccinated and unvaccinated populations (in our case, the differences observed in the low-COVID periods) should be taken into account when evaluating vaccine effectiveness in observation studies....

 

On two independent datasets, we demonstrated a paradoxical pattern of strong association between COVID vaccination status and all-cause mortality, even in periods when almost no COVID-related deaths were present in the population. Vaccinated individuals (especially those shortly after vaccination) exhibit much lower all-cause mortality than the unvaccinated, even in low-COVID periods. This pattern cannot be explained by the true effectiveness of the vaccines in preventing COVID-related deaths. We have demonstrated that the observed association can be explained by the healthy vaccinee effect (a bias in which individuals of poorer health have a lower probability of taking up the vaccine/its further dose) and present a very simple model of health vaccinee effect, which well replicates the pattern observed in the real data."

 

I would strongly recommend that you read the study if you wish to better understand how the researchers came to their conclusions about the impact of the healthy vaccinee effect on the apparent effectiveness of the COVID-19 vaccines.

  

So, the next time that you hear a public health official tout the numerical advantages of vaccinations against the prevention of disease, perhaps you should consider the impact of healthy vaccinee effect on the efficacy statistics that are being touted by governments and their partners in crime, Big Pharma.