Salut, Covid-19, Vacunes

Why has the CDC changed the definition of a vaccine?

A video is circulating on social media stating that the US Centers for Disease Control and Prevention (CDC) has recently changed its definition of a vaccine and that the reason behind this change is "to respond to the declining capacity of current vaccines after covid-19 vaccines were introduced and found not to necessarily prevent disease or provide immunity". This statement is MISLEADING. Yes, the CDC has changed the definition of vaccine and vaccination, but it has not just been discovered that vaccines are not infallible and therefore that is not the reason for the change in definition. 

"After covid-19 vaccines were introduced, and it was discovered that they do not necessarily "prevent disease" or "provide immunity", the CDC altered the definition of vaccines again to say that they simply "produce protection"."

For the definition of vaccine, the CDC has gone from stating that it is "a product that stimulates a person's immune system to produce immunity to a specific disease, thereby protecting against that disease", to now stating that it is "a preparation used to stimulate the body's immune response against a specific disease". 

With the word vaccination they do something similar: rather than considering it as "the act of introducing a vaccine into the body to produce immunity to a specific disease", they now understand it as "the act of introducing a vaccine into the body to produce protection against a specific disease". In other words, they have replaced immunity with protection. 

Hidden interests?

This change has provoked comments from vaccine sceptics, who believe that the change is motivated by the increase in infections that are occurring in the covid-19 vaccinated population. Nevertheless, no vaccine that has ever been approved is 100% effective. Both the World Health Organisation (WHO) and the CDC state this on their websites, and we at Verificat in this infographic, where we point out that not even the smallpox vaccine, the only disease eradicated in humans in history, is infallible.

Therefore, it cannot be affirmed that the CDC has made this move because of something they have only recently discovered. Verificat has tried to contact the CDC to find out the real reason for the change in definition, but at the time of going to press had not yet received a response. The McClatchy news agency managed to contact a spokesperson for the centre, who said that the real reason is that the previous definitions could be interpreted to mean that vaccines "were 100% effective, which has not been the case for any vaccine", so the current definition "is more transparent". In any case, they add, "it is important to emphasise that the changes to the definition do not change the fact that vaccines and the act of vaccination have prevented millions of infections and saved countless lives”.

It is not the first time that the agency has decided to modify the definitions of certain terms on its website. Just a few months ago, they reworded what was meant by 'close contact', and until recently they were considering changing what is known as 'fully vaccinated' as well, although the CDC has so far been reluctant to do so

The author of the message

The commentary is taken from the blog of the journalist and former CBS reporter Sharyll Attkinson, which has been echoed by several media, websites, and the video that you have sent us. This reporter has historically maintained an anti-vaccine position and has recently published articles in which she raises again the debate on whether there is an association between vaccines and autism, a question that has been settled for years since there is no scientific evidence proving that vaccines cause such a thing.


Aquest article és part del projecte "Les Mentides Amenacen la Salut", el primer portal de fact-checking de rumors sobre la covid-19 de Catalunya.

Alguna cosa que t’han enviat o has vist t’ha fet soroll?

Envia’ns un Whatsapp per poder verificar-ho o escriu a [email protected]