The United States Government wants to begin administering a third dose of the Covid-19 vaccine as of September 20 for those who have received the second injection eight months earlier.
This was announced this Wednesday by the Department of Health and Human Services (HHS, in English) in a joint statement with the main medical experts of the Executive.
Before starting this process, the third dose of Pfizer and Moderna vaccines must be approved by the Food and Drug Administration (FDA), the agency in charge of approving the sera, and a scientific committee from the Centers for Disease Control and Prevention (CDC).
The Government explained that it has made this decision after concluding that the effectiveness of vaccines decreases over time after receiving the first doses.
“The available data make it very clear that protection against SARS-CoV-2 infection begins to decline after initial doses of vaccines, and in association with the prevalence of the delta variant, we are beginning to see evidence of a reduction in protection against mild and moderate disease ”, he indicated.
The first to receive the third injection will be the people who were vaccinated first in the US, that is, healthcare professionals and older people living in nursing homes.
The US authorities also anticipated that those who have received the Johnson & Johnson (J&J) vaccine, which is a single dose, may need to receive an additional dose.
In that sense, they detailed that the J&J serum did not begin to be administered in the US until March 2021 (Pfizer’s was the first to receive approval and began to be administered in December) and they are waiting to receive more data on this vaccine in the next few weeks to decide if an additional dose is necessary.
There are currently three vaccines licensed for emergency use in the US: those from Pfizer and Moderna, which require two doses, and the single-dose from J&J.
Those from Pfizer and Moderna use messenger RNA technology, which is a kind of code that the vaccine delivers to cells. This code serves as an instruction manual for the vaccinated’s immune system to learn to recognize the coronavirus and attack it.
Serums like J & J’s use an adenovirus, which is an “inactivated” virus that sends instructions to the vaccinated person’s body to fight COVID-19.
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