Antonio Gutiérrez
Pharmacist and epidemiologist and specialist in infectious diseases
In people [with weakened immune systems] with organ or hematologic transplants, or treatments that depress b cells,, the third dose is clearly necessary, and we will see if a fourth is not forthcoming.
It has been proven that more than 60-70% of these patients do not respond to the vaccine as they should. Even after the third dose the humoral response is very poor, although it remains to be elucidated whether there will be a cellular response.
[The extra dose in patients with weakened immune systems] is essential for them and for their immediate environment and cohabitants.
On the third dose in the general population
Regarding the general population there is nothing that tells us that a third dose is needed. This seems contradictory to the studies that say that the humoral response increases [after the third dose], but that is to be expected. If you expose the body again to an antigen, it is normal for new neutralizing antibodies to be generated. That's to be expected, but with covid-19 everything is rediscovered and reinvented. No one has antibodies against infectious diseases their whole life or the blood would be like eggnog.
The immune system responds like this: it generates humoral response by antibodies that prevent the pathogen from attacking the cell, and when the war is over the antibody levels decrease, as attested by many studies. This is to be expected, we cannot have antibodies in the blood for life. That is why we have B lymphocytes that are in charge of generating new ones against the antigen if necessary.
Of course, antibodies increase [after a third general dose], but that doesn't mean we need them. I have not seen a study that says a third dose is needed in immunocompetent people without underlying pathologies and with a functioning immune system.
On the statement being ambiguous
It's written a little confusingly. It is like saying do what you want, it seems fine to me and I do not get involved in assessing whether it is necessary because you are already doing it.