Ignacio J. Molina Pineda
Professor of Immunology
The non-sterilising nature of all vaccines, not just Pfizer's, has been known to the scientific community from the outset and has never been hidden. The design of all vaccines and the mechanism of virus infection, which occurs through the nasal mucosa, suggested from the outset that any parenteral administration would not interrupt virus transmission as no potent immunity would be triggered in the respiratory mucosa to block the virus in situ.
Achieving a vaccine that interrupts transmission would be ideal, but so far this has not been achieved with any of the vaccines that have been developed because of the complexity involved. In contrast, vaccines have been developed that greatly boost the immune system and are highly effective in preventing severe COVID. This has been the goal of all clinical trials and none have incorporated interruption of transmission, which was clearly a secondary goal. In the epidemiological situation we found ourselves in, the urgent thing was to prevent the development of serious pathologies and, most importantly, to reduce mortality rates. This objective has been fully achieved.