Vaccination Decreases the Infectious Viral Load of Delta Variant SARS-CoV-2 in Asymptomatic Patients

Jessica A Plante; Rafael R G Machado; Brooke M Mitchell; Divya P Shinde; Jordyn Walker; Dionna Scharton; Allan McConnell; Nehad Saada; Jianying Liu; Bilal Khan; Rafael K Campos; Bryan A Johnson; Vineet D Menachery; Corri B Levine; Ping Ren; Susan L F McLellan; Kenneth S Plante; Scott C Weaver

doi:10.3390/v14092071

Vaccination Decreases the Infectious Viral Load of Delta Variant SARS-CoV-2 in Asymptomatic Patients

Viruses. 2022 Sep 18;14(9):2071. doi: 10.3390/v14092071.

Authors

Jessica A Plante^{1

2}, Rafael R G Machado^{2

3}, Brooke M Mitchell^{1

2}, Divya P Shinde^{1

2}, Jordyn Walker^{1

2}, Dionna Scharton^{1

2}, Allan McConnell², Nehad Saada², Jianying Liu^{2

4}, Bilal Khan^{2

5}, Rafael K Campos^{2

6}, Bryan A Johnson², Vineet D Menachery², Corri B Levine⁷, Ping Ren⁸, Susan L F McLellan⁷, Kenneth S Plante^{1

2}, Scott C Weaver^{1

2

6}

Affiliations

¹ World Reference Center for Emerging Viruses and Arboviruses, University of Texas Medical Branch, Galveston, TX 77555, USA.
² Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA.
³ Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, CEP, Brazil.
⁴ Institute of Infectious Diseases, Shenzhen Bay Laboratory, Shenzhen 518071, China.
⁵ Department of Molecular Pathology, Dow University of Health Sciences, Karachi 74200, Pakistan.
⁶ Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA.
⁷ Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA.
⁸ Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA.

Abstract

The Delta variant of SARS-CoV-2 has caused many breakthrough infections in fully vaccinated individuals. While vaccine status did not generally impact the number of viral RNA genome copies in nasopharyngeal swabs of breakthrough patients, as measured by Ct values, it has been previously found to decrease the infectious viral load in symptomatic patients. We quantified the viral RNA, infectious virus, and anti-spike IgA in nasopharyngeal swabs collected from individuals asymptomatically infected with the Delta variant of SARS-CoV-2. Vaccination decreased the infectious viral load, but not the amount of viral RNA. Furthermore, vaccinees with asymptomatic infections had significantly higher levels of anti-spike IgA in their nasal secretions compared to unvaccinated individuals with asymptomatic infections. Thus, vaccination may decrease the transmission risk of Delta, and perhaps other variants, despite not affecting the amount of viral RNA measured in nasopharyngeal swabs.

Keywords: B.1.617.2; COVID-19; IgA; SARS-CoV-2; breakthrough; delta; vaccination.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Asymptomatic Infections
COVID-19* / prevention & control
Humans
Immunoglobulin A
RNA, Viral / genetics
SARS-CoV-2 / genetics
Vaccination
Vaccines*
Viral Load

Vaccination Decreases the Infectious Viral Load of Delta Variant SARS-CoV-2 in Asymptomatic Patients

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