| Title: |
2080. Reduced risk of SARS-CoV-2 infection among household contacts with hybrid immunity from recent COVID-19 vaccination and SARS-CoV-2 infection |
| Authors: |
Rolfes, Melissa A; Talbot, H Keipp; Grace Morrissey, Kerry; Stockwell, Melissa; Maldonado, Yvonne A; McLean, Huong; Lutrick, Karen; Bowman, Natalie M; Rao, Suchitra; Salvatore, Phillip P; Izurieta, Hector; Schmitz, Jonathan; Zhu, Yuwei; Hart, Kimberly W; Battan-Wraith, Steph; Merrill, Lori S; McLaren, Son H; Sano, Ellen; Sarnquist, Clea; Goodman, Sara H; Petrie, Joshua; Ledezma, Karla I; Pryor, Kathleen; Bullock, Ayla; Yang, Amy; Biddle, Jessica E; Smith-Jeffcoat, Sarah E; Johnson, Sheroi; Asturias, Edwin J; Lin, Jessica T; Ellingson, Katherine; Belongia, Edward; Govindaranjan, Prasanthi; Valdez de Romero, Ana; Olivo, Vanessa; Mellis, Alexandra; Grijalva, Carlos G |
| Source: |
Open Forum Infectious Diseases ; volume 10, issue Supplement_2 ; ISSN 2328-8957 |
| Publisher Information: |
Oxford University Press (OUP) |
| Publication Year: |
2023 |
| Description: |
Background COVID-19 vaccines reduce the risk of symptomatic SARS-CoV-2 infection, but it is unclear the extent to which vaccines or prior infection reduce the risk of infection in high transmission settings like households. Methods We screened individuals who tested positive for SARS-CoV-2 (index cases) recruited at 7 sentinel testing sites and through a nationwide effort during Sep 2021–Apr 2023. Index cases and their households (HH) were enrolled ≤6 days after the index case’s illness onset. Household contacts (HHC) had daily self-collected nasal swabs or saliva samples tested by RT-PCR for SARS-CoV-2. We determined COVID-19 vaccination status by plausible self-report (with date) or vaccination records, and prior SARS-CoV-2 infection by self-reported prior positive test (with year) or anti-nucleocapsid antibodies assessed at enrollment. We considered HHC with prior COVID-19 and ≥2 COVID-19 vaccine doses as having “hybrid immunity”, and assessed the effects of ≥2 vaccine doses, prior COVID-19, or hybrid immunity on the risk of PCR-confirmed SARS-CoV-2 infection among HHC by GEE Poisson regression adjusted for age of the HHC, recruitment strategy, household density (ppl/bedroom), and enrollment month. Results We included 1,324 HHC (Fig 1); 73% enrolled May–Nov 2022, when Omicron BA.4/5 predominated; 28% were aged < 18 years (Table 1). Most (89%) had some immunity to COVID-19: 54% from vaccination only, 7% from infection only, and 26% from hybrid immunity. Most HHC without immunity to SARS-CoV-2 were children (64%). Of HHCs, 61% became SARS-CoV-2 positive during follow-up. In a model that accounted for all sources of immunity (figure 2), prior vaccination or prior infection alone did not provide significant protection, only HHC with hybrid immunity had significantly reduced risk of infection (adjusted relative risk: 0.80, 95% confidence interval: 0.68, 0.94; Fig 2). The risk of infection was lowest (43%) when the HHC’s last immunizing event (vaccination or infection) occurred ≤6 months before the ... |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| DOI: |
10.1093/ofid/ofad500.150 |
| Availability: |
https://doi.org/10.1093/ofid/ofad500.150; https://academic.oup.com/ofid/article-pdf/10/Supplement_2/ofad500.150/53761315/ofad500.150.pdf |
| Rights: |
https://creativecommons.org/licenses/by/4.0/ |
| Accession Number: |
edsbas.C6E97EB3 |
| Database: |
BASE |