Ignacio J. Molina Pineda
Professor of Immunology
If you give a second dose, obviously the intensity of the response is going to be greater. The question: do you really need that extra boost in immune response? Most probably not.
With the level of antibodies and cell-mediated immunity you already have, you probably don't need [another dose]. I think we're probably in that situation with the Janssen vaccine.
Sputnik V is the same as Janssen and has a 'lite' version that uses Ad26 (adenovirus 26), just like Janssen, and they say it's also very potent and doesn't need another dose.
As long as there are no indications, and right now there are no indications that a second or third dose is needed, I think the effort has to be put into vaccinating as many people as possible, especially in countries that don't have vaccines.
I think it is much more important that these second and third doses go to countries that have only 1% of the population vaccinated as long as we have no evidence that the immunity that we have achieved in Western countries is declining. It is a global problem and we have to try to reduce infections globally.