Marcos López Hoyos
Scientific Director of the Valdecilla Health Research Institute (IDIVAL) and Professor of Immunology at the University of Cantabria
In severely immunosuppressed individuals, and in solid organ transplant recipients in whom it has been shown that [after a second dose] they do not produce antibodies, a third dose could be indicated. In a certain percentage of seronegatives after the third dose, antibodies are produced, although the EMA itself indicates that it has not been definitively demonstrated that this effect translates into increased protection.
In healthy individuals there is no evidence that the third dose can be of benefit, nor in those over 65 years of age. There is only one study that indicates an increase in the level of antibodies when given 6 months after the second dose. More work is needed to support this, in my view.
By promoting the third dose we are giving the impression that the vaccines are not working, and that is not correct: they are working. The proof is that this summer we have had a high incidence and people have been infected but have not become seriously ill, we have not had a significant increase in hospitalizations. This is not changed by the EMA recommendation.