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Honored Contributor
Posts: 8,366
Registered: ‎05-23-2010

Efficacy versus effectiveness

[ Edited ]

"Vaccine efficacy refers to how well a vaccine performs in a carefully controlled clinical trial, whereas effectiveness describes its performance in the real world. Evidence demonstrates that the authorized COVID-19 vaccines are both efficacious and effective against symptomatic, laboratory-confirmed COVID-19, including severe forms of the disease. In addition, a growing body of evidence suggests that COVID-19 vaccines may also reduce asymptomatic infection, and potentially transmission. Substantial reductions in SARS-CoV-2 infections (both symptomatic and asymptomatic) will have the positive benefit of helping to reduce overall levels of disease, and therefore, transmission in the United States. However, further investigations are ongoing to assess the impact of COVID-19 vaccination on transmission."

 

FROM THE CDC. There's much more about what we know right now about the vaccines and their efficacy and effectiveness here.

 

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwizx_uqx67vAhXaKM0KHeaLDywQ...

 

 

This use of the terms efficacy and effective are the pharmacological meanings of the terms.

Respected Contributor
Posts: 2,139
Registered: ‎08-02-2010

Re: Efficacy versus effectiveness

@Mindy D  I thought efficacy meant how long the perscription, injetion, etc. was potent and effective when left on the shelf. 

Honored Contributor
Posts: 8,366
Registered: ‎05-23-2010

Re: Efficacy versus effectiveness

[ Edited ]

@tobes wrote:

@Mindy D  I thought efficacy meant how long the perscription, injetion, etc. was potent and effective when left on the shelf. 


@tobes @Could you be thinking of the term expiry date?

Respected Contributor
Posts: 2,139
Registered: ‎08-02-2010

Re: Efficacy versus effectiveness

[ Edited ]

@Mindy D   Hi Mindy....I found this definition for effecacy.  See to be double speak.

 

Efficacy trials (explanatory trials) determine whether an intervention produces the expected result under ideal circumstances. Effectiveness trials (pragmatic trials) measure the degree of beneficial effect under “real world” clinical settings.

 

 

 

 

Esteemed Contributor
Posts: 7,616
Registered: ‎02-19-2014

Re: Efficacy versus effectiveness

Real world practical success. This is really fabulous!

 

"a growing body of evidence suggests that COVID-19 vaccines may also reduce asymptomatic infection, and potentially transmission."

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Respected Contributor
Posts: 3,959
Registered: ‎03-16-2010

Re: Efficacy versus effectiveness

Thanks for putting this information out there @Mindy D, for those that are interested in learning the difference!  


* Freedom has a taste the protected will never know *
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Respected Contributor
Posts: 3,959
Registered: ‎03-16-2010

Re: Efficacy versus effectiveness


@tobes wrote:

@Mindy D   Hi Mindy....I found this definition for effecacy.  See to be double speak.

 

Efficacy trials (explanatory trials) determine whether an intervention produces the expected result under ideal circumstances. Effectiveness trials (pragmatic trials) measure the degree of beneficial effect under “real world” clinical settings.

 

 

 

 


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It can seem like double speak @tobes, but it really isn't clinically.  Efficacy in terms of a vaccine is determined as a calculated percentage determing how well a vaccine works at preventing disease or serious disease in the vaccine group as compared to the placebo group.  That will  yield a percentage.  But that percentage is in a smaller population than when you actually get it out into the population.  That is when they can make better determinations on how effective it is.

 

For the mRNA vaccines combined, they had a total group of around 70,000 subjects.  So the efficacy is determined based on those 70,000 people.  

 

Now that the vaccine is released into the broader population, there are currently tens of millions of people that have received at least one dose mRNA vaccine worldwide.  Once you have that broad of a vaccinated population, they are able to get a much better picture of how effective the vaccine is at preventing disease, preventing serious disease,&/or preventing deaths.  That will determine the effectiveness out in the real world, so to speak. 

 

Usually we expect to see the effectiveness decrease when you get the vaccine out into the larger population.  Not unusual for the effectiveness of any vaccine to decrease from the determined efficacy in the clinical trial.  However to date, the effectiveness of the mRNA vaccines are holding steady with the same percentage as was determined for efficacy in the clinical trial.   Fairly impressive so far.  

 

 


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