In 2008, it was known that vaccines fail for mucosal immunity. Saliva of the vaxxed is poor in immunity. Gates-Fau Chi vaccine cartel deliberately failed to mention that they knew boosters would be required, but shirking their responsibility because they knew it would create protest and resistance:
Dec 2021 Low Mucosal Vaccination
This work was funded by the Department of Medicine and Surgery, University of Insubria, and partially supported by Fondazione Umberto Veronesi (COVID-19 Insieme per la ricerca di tutti, 2020).
pubmed.ncbi.nlm.nih.gov
And because Baric is implicated in producing chimeraviruses in the lab, Baric et al, mention the same problem before this publication in 2008 and before SARS-C0V-2 , and is about as absurd as not telling Trump about the critical timing of hydroxychloroquine to ensure its failure:
'In spite of long-term efforts, fully effective animal vaccines to prevent CoV infection of mucosal tissues remains elusive, and single-dose live but not killed vaccines induced the most consistent protection (Saif LJ, [2004] Animal Coronavirus Vaccines: Lessons for SARS, Developmental Biology 119: 129-140). Vaccines inducing mucosal immunity are the most effective, but unfortunately, these vaccines often are short-lived, a limitation observed even after natural infection.
As a consequence, these vaccines may not prevent reinfection and effective immunization may require frequent boosting, factors complicating CoV vaccine design.'
(Enjuanes L, DeDiego ML, Alvarez E, Capiscol C, Baric R, Vaccines for Severe Acute Respiratory Syndrome Virus and Other Coronaviruses, in Ch. 25 The Nidoviruses, ASM Press, Washington, D.C., 2008)