key: cord-0901295-coge7yep
authors: Martinez, Diego A; Klein, Eili Y; Parent, Cassandra; Prieto, Diana; Bigelow, Benjamin F; Saxton, Ronald E; Page, Kathleen R
title: Latino Household Transmission of SARS-CoV-2
date: 2021-08-31
journal: Clin Infect Dis
DOI: 10.1093/cid/ciab753
sha: f39e6c4f0d57ed3f9380ae639e99ec2bdff76dbc
doc_id: 901295
cord_uid: coge7yep

We assessed temporal changes in the household secondary attack rate of SARS-CoV-2 and identified risk factors for transmission in vulnerable Latino households of Baltimore, Maryland. The household SAR was 45.8%, and it appeared to increase as the alpha variant spread, highlighting the magnified risk of spread in unvaccinated populations.

The coronavirus disease 2019 (COVID-19) pandemic has disproportionately affected Latinos in the US with increased infection, hospitalization, and mortality rates. 1 Greater housing density is one of the primary hypotheses suggested for this disparity. 2 However, limited data exist on household transmission rates among Latinos in the US, and none since the emergence of the alpha variant (B.1.1.7). 3, 4 Latinos of Baltimore, in particular, are the fastestgrowing ethnic group and account for 5.5% of the population. They also are more likely to be foreign-born and undocumented and to have a lower income, lower educational attainment, lower insurance coverage, and lower English proficiency when compared with the general Latino population of the US. 5, 6 Recent studies have shown a high prevalence of COVID-19 in this community. 7, 8 We assessed temporal changes in the household secondary attack rate (SAR) and identified risk factors for transmission in vulnerable Latino households of Baltimore, Maryland.

Samples and patient characteristics were collected at free, community-based Latino testing events in Baltimore, Maryland, between June 11, 2020, and May 20, 2021. Patients and their household members were encouraged to return to the same care centers for testing, and active case follow-up was used to ascertain subsequent diagnoses in a household. Samples were tested using the reverse transcriptase-polymerase chain reaction (RT-PCR) test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Primary and secondary household cases were identified as a positive SARS-CoV-2 RT-PCR test, with secondary cases testing positive within 14 days after exposure to a primary case. Ambiguities in a household primary case were resolved through random imputation. That is, if two or more individuals in a A c c e p t e d M a n u s c r i p t household tested positive at the same time, where any infectee who could have been infected by multiple individuals was randomly assigned one as their actual infector. The at-risk cohort was identified as all individuals living in the address of a primary case. The SAR was calculated as the percentage of at-risk individuals who were later confirmed to have SARS-CoV-2 infection. 2018 CDC US social vulnerability index data at the census tract-level was linked to the household address of every patient.

Segmented regression analysis was used to estimate changes in SAR over time. ANOVA was used to compare trends in SAR and testing volume over time. Mixed-effects logistic regression modeling was used to calculate the adjusted infection risk, accounting for clustering of exposed subjects within households. All analyses were performed with R week (P < .001; Figure 1A ). Fluctuations in testing volume overtime did not correlate with SAR (P = .298; Figure 1B ). Independent factors significantly associated with higher household transmission risk included residing in neighborhoods of higher socioeconomic vulnerability (adjusted odds ratio (adj.

OR) for those living in the poorest areas, 1.87; 95% confidence interval (CI), 0.94-3.71; P = .0741) and denser housing (adj. OR for those living in 4-people households, 2.06; 95% CI, 0.99-4.29; P = .0525).

At Latino testing events in Baltimore, the household SAR of SARS-CoV-2 was 45.8%, corresponding to some of the highest rates reported early in the COVID-19 pandemic. 3, 4 The SAR appeared to increase in the Latino community as the alpha variant spread, consistent with its noted higher transmissibility. 9 The rising SAR, which occurred before vaccination was widespread, highlights the magnified risk of spread in unvaccinated populations; Latinos remain 30% less likely to be vaccinated against COVID-19 than non-Latino whites. 10 While testing inclusion criteria were standardized across sites and over time, differential awareness of testing events, an inability to identify and test every potential household contact, and rule out common infections may contribute to bias in SAR estimation. That is, some of the coded secondary cases might have been exposed at the same time as the primary case, and not infected within the household. The high community transmission documented in Baltimore suggests that exposure to SARS-CoV-2 could have occurred elsewhere. 7, 8 M a n u s c r i p t M a n u s c r i p t M a n u s c r i p t Figure 1 

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