| Title: |
SARS-CoV-2 infection risk among vaccinated and unvaccinated household members during the Alpha variant surge - Denver, Colorado, and San Diego, California, January-April 2021. |
| Authors: |
McCormick, David; Konkle, Stacey; Magleby, Reed; Chakrabarti, Ayan; Cherney, Blake; Lindell, Kristine; Namageyo-Funa, Apophia; Visser, Susanna; Soto, Raymond; Donnelly, Marisa; Stringer, Ginger; Austin, Brett; Beatty, Mark; Stous, Sarah; Albanese, Bernadette; Chu, Victoria; Chuey, Meagan; Dietrich, Elizabeth; Drobeniuc, Jan; Folster, Jennifer; Killerby, Marie; Lehman, Jennifer; McDonald, Eric; Ruffin, Jasmine; Schwartz, Noah; Sheldon, Sarah; Sleweon, Sadia; Thornburg, Natalie; Hughes, Laura; Petway, Marla; Tong, Suxiang; Whaley, Melissa; Kirking, Hannah; Tate, Jacqueline; Hsu, Christopher; Matanock, Almea |
| Source: |
Vaccine, vol 40, iss 33 |
| Publisher Information: |
eScholarship, University of California |
| Publication Year: |
2022 |
| Collection: |
University of California: eScholarship |
| Subject Terms: |
COVID-19; Household transmission; SARS-CoV-2; Vaccination; Vaccine effectiveness; COVID-19 Vaccines; California; Colorado; Humans |
| Description: |
BACKGROUND: COVID-19 vaccination reduces SARS-CoV-2 infection and transmission. However, evidence is emerging on the degree of protection across variants and in high-transmission settings. To better understand the protection afforded by vaccination specifically in a high-transmission setting, we examined household transmission of SARS-CoV-2 during a period of high community incidence with predominant SARS-CoV-2 B.1.1.7 (Alpha) variant, among vaccinated and unvaccinated contacts. METHODS: We conducted a household transmission investigation in San Diego County, California, and Denver, Colorado, during January-April 2021. Households were enrolled if they had at least one person with documented SARS-CoV-2 infection. We collected nasopharyngeal swabs, blood, demographic information, and vaccination history from all consenting household members. We compared infection risks (IRs), RT-PCR cycle threshold values, SARS-CoV-2 culture results, and antibody statuses among vaccinated and unvaccinated household contacts. RESULTS: We enrolled 493 individuals from 138 households. The SARS-CoV-2 variant was identified from 121/138 households (88%). The most common variants were Alpha (75/121, 62%) and Epsilon (19/121, 16%). There were no households with discordant lineages among household members. One fully vaccinated secondary case was symptomatic (13%); the other 5 were asymptomatic (87%). Among unvaccinated secondary cases, 105/108 (97%) were symptomatic. Among 127 households with a single primary case, the IR for household contacts was 45% (146/322; 95% Confidence Interval [CI] 40-51%). The observed IR was higher in unvaccinated (130/257, 49%, 95% CI 45-57%) than fully vaccinated contacts (6/26, 23%, 95% CI 11-42%). A lower proportion of households with a fully vaccinated primary case had secondary cases (1/5, 20%) than households with an unvaccinated primary case (66/108, 62%). CONCLUSIONS: Although SARS-CoV-2 infections in vaccinated household contacts were reported in this high transmission setting, full vaccination ... |
| Document Type: |
article in journal/newspaper |
| File Description: |
application/pdf |
| Language: |
unknown |
| Relation: |
qt38h0619s; https://escholarship.org/uc/item/38h0619s; https://escholarship.org/content/qt38h0619s/qt38h0619s.pdf |
| DOI: |
10.1016/j.vaccine.2022.06.066 |
| Availability: |
https://escholarship.org/uc/item/38h0619s; https://escholarship.org/content/qt38h0619s/qt38h0619s.pdf; https://doi.org/10.1016/j.vaccine.2022.06.066 |
| Rights: |
public |
| Accession Number: |
edsbas.C0DF691F |
| Database: |
BASE |