Waning of SARS-CoV-2 booster viral-load reduction effectiveness

Matan Levine-Tiefenbrun, Idan Yelin, Hillel Alapi, Esma Herzel, Jacob Kuint, Gabriel Chodick, Sivan Gazit, Tal Patalon*, Roy Kishony*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


The BNT162b2 COVID-19 vaccine has been shown to reduce viral load of breakthrough infections (BTIs), an important factor affecting infectiousness. This viral-load protective effect has been waning with time post the second vaccine and later restored with a booster shot. It is currently unclear though for how long this regained effectiveness lasts. Analyzing Ct values of SARS-CoV-2 qRT-PCR tests of over 22,000 infections during a Delta-variant-dominant period in Israel, we find that this viral-load reduction effectiveness significantly declines within months post the booster dose. Adjusting for age, sex and calendric date, Ct values of RdRp gene initially increases by 2.7 [CI: 2.3-3.0] relative to unvaccinated in the first month post the booster dose, yet then decays to a difference of 1.3 [CI: 0.7-1.9] in the second month and becomes small and insignificant in the third to fourth months. The rate and magnitude of this post-booster decline in viral-load reduction effectiveness mirror those observed post the second vaccine. These results suggest rapid waning of the booster’s effectiveness in reducing infectiousness, possibly affecting community-level spread of the virus.

Original languageEnglish
Article number1237
JournalNature Communications
Issue number1
StatePublished - Dec 2022


FundersFunder number
Edmond J. Safra Center for Bioinformatics at Tel-Aviv University
Israel Science Foundation KillCorona-Curbing Coronavirus Research Program3633/19


    Dive into the research topics of 'Waning of SARS-CoV-2 booster viral-load reduction effectiveness'. Together they form a unique fingerprint.

    Cite this