AbstractAn important, and often neglected, aspect of vaccine effectiveness is its impact on pathogen transmissibility, harboring major implications for public health policies. As viral load is a prominent factor affecting infectivity, its laboratory surrogate, qRT-PCR cycle threshold (Ct), can be used to investigate the infectivity-related component of vaccine effectiveness. While vaccine waning has previously been observed for viral load, during the Delta wave, it is yet unknown how Omicron viral load is affected by vaccination status, and whether vaccine-derived and natural infection protection are sustainable. By analyzing results of more than 460,000 individuals we show that while recent vaccination reduces Omicron viral load, its effect wanes rapidly. In contrast, a significantly slower waning rate is demonstrated for recovered COVID-19 individuals. Thus, while the vaccine is effective in decreasing morbidity and mortality, their relative minute effect on transmissibility and rapid waning call for reassessment of the scientific justification for “vaccine certificate”, as it may promote false reassurance and promiscuous behavior.