Bombshell Study: Vaccinated 5X More Contagious Than the Unvaccinated 10 Days After SARS-CoV-2 Infection

by TrialSite Staff | Aug 11, 2022

Published recently in the prestigious New England Journal of Medicine (NEJM), a study led by Massachusetts-based physician-scientists leads to a disturbing discovery: individuals fully vaccinated and boosted against COVID-19 actually recover markedly more slowly from the illness and surprisingly, even remain contagious for lengthier periods of time as compared to unvaccinated persons. While the study didn’t investigate implications associated with illness severity, the findings nonetheless raise significant questions for consideration. This study was approved by the institutional review board and the institutional biosafety committee at Mass General Brigham, and informed consent was obtained from all the participants. The takeaway from this study could be profound should the results scale out to larger cohorts. People that are vaccinated remain five times as contagious as those who are unvaccinated ten days after SARS-CoV-2 infection. Put another way, the vaccinated continue to transmit the disease significantly more than the unvaccinated should the data hold up across broader investigation.


This longitudinal cohort study produces surprising findings. While data indicate the vaccine reduces the severity of the disease overall, the study team found no marked difference involving the median duration of viral shedding among those participants who were unvaccinated, those who were vaccinated yet not boosted, and those who were both vaccinated and boosted.

The study led by a team of investigators from Brigham and Women’s Hospital, Massachusetts General Hospital, and Ragon Institute enrolled 66 participants, with 32 having samples that were sequenced and identified as the Delta variant, and 34 with samples identified as Omicron (BA.1) inclusive of sublineages. The study excluded any subjects that were treated with a COVID-19 therapy and included only one person with symptomatic infection.

Troubling Data

The study team observed that by day five after initial SARS-CoV-2 infection, fewer than 25% of the unvaccinated participants remained contagious with COVID-19. But approximately 70% of boosted subjects continued to carry SARS-CoV-2 viral particles! What about the partially vaccinated? About 50% of the subjects continued to remain contagious five days out.

Bombshell Data

Yet at ten days after infection, 31% of those study participants continued to carry active, live SARS-CoV-2 virus, however, only 6% of the unvaccinated cohort remained contagious. The data showed that persons who have received a third booster according to these study results are five times more likely to remain contagious at the post infection 10-day mark than unvaccinated persons.


For starters, if this data holds true to larger populations, the vaccinated become the walking contagious compared to the unvaccinated. Moreover, perhaps this study finding better explains the Paxlovid effectiveness issues, as many vaccinated persons get ill and take the Pfizer drug only to become ill again after completing the five-day course.

Lead Research/Investigator

Other authors can be found at the source.

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