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

Nat Commun. 2022 Mar 4;13(1):1237. doi: 10.1038/s41467-022-28936-y.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Algorithms
  • BNT162 Vaccine / administration & dosage
  • BNT162 Vaccine / immunology*
  • COVID-19 / immunology*
  • COVID-19 / prevention & control
  • COVID-19 / virology
  • COVID-19 Vaccines / administration & dosage
  • COVID-19 Vaccines / immunology*
  • Female
  • Humans
  • Immunization, Secondary / methods*
  • Immunization, Secondary / statistics & numerical data
  • Immunogenicity, Vaccine / immunology
  • Linear Models
  • Male
  • Middle Aged
  • SARS-CoV-2 / genetics
  • SARS-CoV-2 / immunology*
  • SARS-CoV-2 / physiology
  • Time Factors
  • Treatment Outcome
  • Vaccination / methods
  • Vaccination / statistics & numerical data
  • Viral Load / immunology*

Substances

  • COVID-19 Vaccines
  • BNT162 Vaccine

Supplementary concepts

  • SARS-CoV-2 variants