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Comparison of infectious SARS-CoV-2 from the nasopharynx of vaccinated and unvaccinated individuals
Preprint
in English
| medRxiv
| ID: ppmedrxiv-21268460
ABSTRACT
The frequency of SARS-CoV-2 breakthrough infections in fully vaccinated individuals increased with the emergence of the Delta variant, particularly with longer time from vaccine completion. However, whether breakthrough infections lead to onward transmission remains unclear. Here, we conducted a study involving 125 patients comprised of 72 vaccinated and 53 unvaccinated individuals, to assess the levels of infectious virus in vaccinated and unvaccinated individuals. Quantitative plaque assays showed no significant differences in the titers of virus between these cohorts. However, the proportion of nasopharyngeal samples with culturable virus was lower in the vaccinated patients relative to unvaccinated patients (21% vs. 40%). Finally, time-to-event analysis with Kaplan-Myer curves revealed that protection from culturable infectious virus waned significantly starting at 5 months after completing a 2-dose regimen of mRNA vaccines. These results have important implications in timing of booster dose to prevent onward transmission from breakthrough cases.
cc_by_nc_nd
Full text:
Available
Collection:
Preprints
Database:
medRxiv
Type of study:
Cohort_studies
/
Observational study
/
Prognostic study
Language:
English
Year:
2022
Document type:
Preprint