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[Preprint]. 2021 Oct 20:2021.10.18.21265113. [Version 1] doi: 10.1101/2021.10.18.21265113

Immune Responses in Fully Vaccinated Individuals Following Breakthrough Infection with the SARS-CoV-2 Delta Variant in Provincetown, Massachusetts

Ai-ris Y Collier, Catherine M Brown, Katherine Mcmahan, Jingyou Yu, Jinyan Liu, Catherine Jacob-Dolan, Abishek Chandrashekar, Dylan Tierney, Jessica L Ansel, Marjorie Rowe, Daniel Sellers, Kunza Ahmad, Ricardo Aguayo, Tochi Anioke, Sarah Gardner, Mazuba Siamatu, Lorraine Bermudez Rivera, Michele R Hacker, Lawrence C Madoff, Dan H Barouch
PMCID: PMC8547536  PMID: 34704104

ABSTRACT

Background

A cluster of over a thousand infections with the SARS-CoV-2 delta variant was identified in a predominantly fully vaccinated population in Provincetown, Massachusetts in July 2021. Immune responses in breakthrough infections with the SARS-CoV-2 delta variant remain to be defined.

Methods

Humoral and cellular immune responses were assessed in 35 vaccinated individuals who were tested for SARS-CoV-2 in the Massachusetts Department of Public Health outbreak investigation.

Results

Vaccinated individuals who tested positive for SARS-CoV-2 demonstrated substantially higher antibody responses than vaccinated individuals who tested negative for SARS-CoV-2, including 28-fold higher binding antibody titers and 34-fold higher neutralizing antibody titers against the SARS-CoV-2 delta variant. Vaccinated individuals who tested positive also showed 4.4-fold higher Spike-specific CD8+ T cell responses against the SARS-CoV-2 delta variant than vaccinated individuals who tested negative.

Conclusions

Fully vaccinated individuals developed robust anamnestic antibody and T cell responses following infection with the SARS-CoV-2 delta variant. These data suggest important immunologic benefits of vaccination in the context of breakthrough infections.

Full Text

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