BACKGROUND: Households have emerged as important venues for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. Little is known, however, regarding the magnitude and determinants of household transmission in increasingly vaccinated populations. METHODS: From September 2020 to January 2022, symptomatic nonhospitalized individuals with SARS-CoV-2 infection by RNA detection were identified within 5 days of symptom onset; all individuals resided with at least 1 other SARS-CoV-2-uninfected household member. These infected persons (cases) and their household members (contacts) were subsequently followed with questionnaire-based measurement and serial nasal specimen collection. The primary outcome was SARS-CoV-2 infection among contacts. RESULTS: We evaluated 42 cases and their 74 household contacts. Among the contacts, 32 (43%) became infected, of whom 5 (16%) were asymptomatic; 81% of transmissions occurred by 5 days after the case's symptom onset. From 21 unvaccinated cases, 14-day cumulative incidence of SARS-CoV-2 infection among contacts was 18/40 (45% [95% confidence interval {CI}, 29%-62%]), most of whom were unvaccinated. From 21 vaccinated cases, 14-day cumulative incidence of SARS-CoV-2 infection was 14/34 (41% [95% CI, 25%-59%]) among all contacts and 12/29 (41% [95% CI, 24%-61%]) among vaccinated contacts. At least 1 comorbid condition among cases and 10 or more days of RNA detection in cases were associated with increased risk of infection among contacts. CONCLUSIONS: Among households including individuals with symptomatic SARS-CoV-2 infection, both vaccinated-to-vaccinated and unvaccinated-to-unvaccinated transmission of SARS-CoV-2 to household contacts was common. Because vaccination alone did not notably reduce risk of infection, household contacts will need to employ additional interventions to avoid infection. Published by Oxford University Press on behalf of Infectious Diseases Society of America 2022.
BACKGROUND: Households have emerged as important venues for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. Little is known, however, regarding the magnitude and determinants of household transmission in increasingly vaccinated populations. METHODS: From September 2020 to January 2022, symptomatic nonhospitalized individuals with SARS-CoV-2 infection by RNA detection were identified within 5 days of symptom onset; all individuals resided with at least 1 other SARS-CoV-2-uninfected household member. These infected persons (cases) and their household members (contacts) were subsequently followed with questionnaire-based measurement and serial nasal specimen collection. The primary outcome was SARS-CoV-2 infection among contacts. RESULTS: We evaluated 42 cases and their 74 household contacts. Among the contacts, 32 (43%) became infected, of whom 5 (16%) were asymptomatic; 81% of transmissions occurred by 5 days after the case's symptom onset. From 21 unvaccinated cases, 14-day cumulative incidence of SARS-CoV-2 infection among contacts was 18/40 (45% [95% confidence interval {CI}, 29%-62%]), most of whom were unvaccinated. From 21 vaccinated cases, 14-day cumulative incidence of SARS-CoV-2 infection was 14/34 (41% [95% CI, 25%-59%]) among all contacts and 12/29 (41% [95% CI, 24%-61%]) among vaccinated contacts. At least 1 comorbid condition among cases and 10 or more days of RNA detection in cases were associated with increased risk of infection among contacts. CONCLUSIONS: Among households including individuals with symptomatic SARS-CoV-2 infection, both vaccinated-to-vaccinated and unvaccinated-to-unvaccinated transmission of SARS-CoV-2 to household contacts was common. Because vaccination alone did not notably reduce risk of infection, household contacts will need to employ additional interventions to avoid infection. Published by Oxford University Press on behalf of Infectious Diseases Society of America 2022.
Authors: Miguel Garcia-Knight; Khamal Anglin; Michel Tassetto; Scott Lu; Amethyst Zhang; Sarah A Goldberg; Adam Catching; Michelle C Davidson; Joshua R Shak; Mariela Romero; Jesus Pineda-Ramirez; Ruth Diaz-Sanchez; Paulina Rugart; Kevin Donohue; Jonathan Massachi; Hannah M Sans; Manuella Djomaleu; Sujata Mathur; Venice Servellita; David McIlwain; Brice Gaudiliere; Jessica Chen; Enrique O Martinez; Jacqueline M Tavs; Grace Bronstone; Jacob Weiss; John T Watson; Melissa Briggs-Hagen; Glen R Abedi; George W Rutherford; Steven G Deeks; Charles Chiu; Sharon Saydah; Michael J Peluso; Claire M Midgley; Jeffrey N Martin; Raul Andino; J Daniel Kelly Journal: PLoS Pathog Date: 2022-09-12 Impact factor: 7.464
Authors: Michel Tassetto; Miguel Garcia-Knight; Khamal Anglin; Scott Lu; Amethyst Zhang; Mariela Romero; Jesus Pineda-Ramirez; Ruth Diaz Sanchez; Kevin C Donohue; Karen Pfister; Curtis Chan; Sharon Saydah; Melissa Briggs-Hagen; Michael J Peluso; Jeffrey N Martin; Raul Andino; Claire M Midgley; J Daniel Kelly Journal: MMWR Morb Mortal Wkly Rep Date: 2022-09-09 Impact factor: 35.301