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Transmission of SARS-CoV-2 Delta Variant Among Vaccinated Healthcare Workers, Vietnam

31 Pages Posted: 11 Oct 2021

See all articles by Nguyen Van Vinh Chau

Nguyen Van Vinh Chau

Hospital for Tropical Diseases

Nghiem My Ngoc

Hospital for Tropical Diseases

Lam Anh Nguyet

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Vo Minh Quang

Hospital for Tropical Diseases

Nguyen Thi Han Ny

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Dao Bach Khoa

Hospital for Tropical Diseases

Nguyen Thanh Phong

Hospital for Tropical Diseases

Le Mau Toan

Hospital for Tropical Diseases

Nguyen Thi Thu Hong

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Nguyen Thi Kim Tuyen

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Voong Vinh Phat

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Le Nguyen Truc Nhu

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Nguyen Huynh Thanh Truc

Hospital for Tropical Diseases

Bui Thi Ton That

Hospital for Tropical Diseases

Huynh Phuong Thao

Hospital for Tropical Diseases

Tran Nguyen Phuong Thao

Hospital for Tropical Diseases

Vo Trong Vuong

Hospital for Tropical Diseases

Tran Thi Thanh Tam

Hospital for Tropical Diseases

Ngo Tan Tai

Hospital for Tropical Diseases

Ho The Bao

Hospital for Tropical Diseases

Huynh Thi Kim Nhung

Hospital for Tropical Diseases

Nguyen Thi Ngoc Minh

Hospital for Tropical Diseases

Nguyen Thi My Tien

Hospital for Tropical Diseases

Nguy Cam Huy

Hospital for Tropical Diseases

Marc Choisy

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Dinh Nguyen Huy Man

Hospital for Tropical Diseases

Dinh Thi Bich Ty

Hospital for Tropical Diseases

Nguyen To Anh

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Le Thi Tam Uyen

Hospital for Tropical Diseases

Tran Nguyen Hoang Tu

Hospital for Tropical Diseases

Lam Minh Yen

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Nguyen Thanh Dung

Hospital for Tropical Diseases

Le Manh Hung

Hospital for Tropical Diseases

Nguyen Thanh Truong

Hospital for Tropical Diseases

Tran Tan Thanh

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Guy Thwaites

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Le Van Tan

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

OUCRU COVID-19 Research Group

More...

Abstract

Background: Data on breakthrough SARS-CoV-2 Delta variant infections are limited.

Methods: We studied breakthrough infections among healthcare workers of a major infectious diseases hospital in Vietnam. We collected demographics, vaccination history and results of PCR diagnosis alongside clinical data. We measured SARS-CoV-2 (neutralizing) antibodies at diagnosis, and at week 1, 2 and 3 after diagnosis. We sequenced the viruses using ARTIC protocol.

Findings: Between 11th–25th June 2021 (week 7–8 after dose 2), 69 healthcare workers were tested positive for SARS-CoV-2. 62 participated in the clinical study. 49 were (pre)symptomatic with one requiring oxygen supplementation. All recovered uneventfully. 23 complete-genome sequences were obtained. They all belonged to the Delta variant, and were phylogenetically distinct from the contemporary Delta variant sequences obtained from community transmission cases, suggestive of ongoing transmission between the workers. Viral loads of breakthrough Delta variant infection cases were 251 times higher than those of cases infected with old strains detected between March-April 2020. Time from diagnosis to PCR negative was 8–33 days (median: 21). Neutralizing antibody levels after vaccination and at diagnosis of the cases were lower than those in the matched uninfected controls. There was no correlation between vaccine-induced neutralizing antibody levels and viral loads or the development of symptoms.

Interpretation: Breakthrough Delta variant infections are associated with high viral loads, prolonged PCR positivity, and low levels of vaccine-induced neutralizing antibodies, explaining the transmission between the vaccinated people. Physical distancing measures remain critical to reduce SARS-CoV-2 Delta variant transmission.

Funding: Wellcome (106680/B/14/Z and 204904/Z/16/Z).

Declaration of Interest: None to declare.

Ethical Approval: The study was approved by the Institutional Review Board of HTD and the Oxford Tropical Research Ethics Committee, University of Oxford, UK.

Keywords: Delta variant, Oxford-AstraZeneca, COVID-19, vaccine breakthrough, Vietnam

Suggested Citation

Chau, Nguyen Van Vinh and Ngoc, Nghiem My and Nguyet, Lam Anh and Quang, Vo Minh and Ny, Nguyen Thi Han and Khoa, Dao Bach and Phong, Nguyen Thanh and Toan, Le Mau and Hong, Nguyen Thi Thu and Tuyen, Nguyen Thi Kim and Phat, Voong Vinh and Nhu, Le Nguyen Truc and Truc, Nguyen Huynh Thanh and That, Bui Thi Ton and Thao, Huynh Phuong and Thao, Tran Nguyen Phuong and Vuong, Vo Trong and Tam, Tran Thi Thanh and Tai, Ngo Tan and Bao, Ho The and Nhung, Huynh Thi Kim and Minh, Nguyen Thi Ngoc and Tien, Nguyen Thi My and Huy, Nguy Cam and Choisy, Marc and Man, Dinh Nguyen Huy and Ty, Dinh Thi Bich and Anh, Nguyen To and Uyen, Le Thi Tam and Tu, Tran Nguyen Hoang and Yen, Lam Minh and Dung, Nguyen Thanh and Hung, Le Manh and Truong, Nguyen Thanh and Thanh, Tran Tan and Thwaites, Guy and Tan, Le Van and Group, OUCRU COVID-19 Research, Transmission of SARS-CoV-2 Delta Variant Among Vaccinated Healthcare Workers, Vietnam. EClinicalMedicine, Volume 41, November 2021, 11043 https://doi.org/10.1016/j.eclinm.2021.101143 https://www.sciencedirect.com/science/article/pii/S2589537021004235, Available at SSRN: https://ssrn.com/abstract=3897733 or http://dx.doi.org/10.2139/ssrn.3897733

Nguyen Van Vinh Chau

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Nghiem My Ngoc

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Lam Anh Nguyet

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Vo Minh Quang

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Nguyen Thi Han Ny

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Dao Bach Khoa

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Nguyen Thanh Phong

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Le Mau Toan

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Nguyen Thi Thu Hong

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Nguyen Thi Kim Tuyen

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Voong Vinh Phat

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Le Nguyen Truc Nhu

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Nguyen Huynh Thanh Truc

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Bui Thi Ton That

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Huynh Phuong Thao

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Tran Nguyen Phuong Thao

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Vo Trong Vuong

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Tran Thi Thanh Tam

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Ngo Tan Tai

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Ho The Bao

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Huynh Thi Kim Nhung

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Nguyen Thi Ngoc Minh

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Nguyen Thi My Tien

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Nguy Cam Huy

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Marc Choisy

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Dinh Nguyen Huy Man

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Dinh Thi Bich Ty

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Nguyen To Anh

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Le Thi Tam Uyen

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Tran Nguyen Hoang Tu

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Lam Minh Yen

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Nguyen Thanh Dung

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Le Manh Hung

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Nguyen Thanh Truong

Hospital for Tropical Diseases ( email )

Ho Chi Minh City
Vietnam

Tran Tan Thanh

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

Guy Thwaites

Hospital of Tropical Diseases - Oxford University Clinical Research Unit

Vietnam

Le Van Tan (Contact Author)

Hospital of Tropical Diseases - Oxford University Clinical Research Unit ( email )

Vietnam

No contact information is available for OUCRU COVID-19 Research Group

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