Hepatitis A Exposure Response and Outbreak Prevention in a Large Urban Jail - Los Angeles County, California, May-July 2023.

Correctional settings provide a high-risk environment for hepatitis A transmission because of the high proportion of homelessness and injection drug use among persons who are incarcerated. On May 30, 2023, Los Angeles County Department of Public Health informed the Communicable Disease Surveillance and Control (CDSC) unit of the Los Angeles County Jail system that a symptomatic incarcerated person had received a positive test result for acute hepatitis A. Upon learning the next day that the patient was a food handler, CDSC staff members identified 5,830 potential contacts of the index patient, 1,702 of whom had been released from the jail. During June 1-12, a total of 2,766 contacts who did not have a documented history of hepatitis A serology or vaccination that could be confirmed from the electronic health record or state immunization registry were identified. These persons were offered hepatitis A vaccination as postexposure prophylaxis; 1,510 (54.6%) accepted vaccination. Contacts who were food handlers without confirmed evidence of immunity and who declined vaccination were removed from food-handling duties for the duration of their potential incubation period. No additional cases were identified. Identifying contacts promptly and using immunization and serology records to ensure rapid delivery of postexposure prophylactic vaccine can help prevent hepatitis A transmission during exposures among incarcerated populations.

Mpox Outbreak - Los Angeles County, California, May 4-August 17, 2023.

Since May 2022, approximately 2,500 mpox cases have been reported in Los Angeles County (LAC), California. Beginning in May 2023, the LAC Department of Public Health observed a consistent increase in mpox cases after a prolonged period of low incidence. A total of 56 cases were identified during May 4-August 17, 2023. A minority of mpox patients were fully vaccinated (29%). One patient was hospitalized; no deaths were reported. Two cases of reinfection occurred, both of which were associated with mild illness. The increasing number of cases during this period was significant, as few other health departments in the United States reported an increase in mpox cases during the same period. The outbreak spread similarly to the 2022 U.S. mpox outbreak, mainly through sexual contact among gay, bisexual, and other men who have sex with men. Vaccination against mpox became available in June 2022 and has been shown to be effective at preventing mpox disease. This outbreak was substantially smaller than the 2022 mpox outbreak in LAC (2,280 cases); possible explanations for the lower case count include increased immunity provided from vaccination against mpox and population immunity from previous infections. Nonetheless, mpox continues to spread within LAC, and preventive measures, such as receipt of JYNNEOS vaccination, are recommended for persons at risk of Monkeypox virus exposure.

Distress about social problems and tobacco and cannabis use outcomes among young adults in Los Angeles County.

OBJECTIVE: To examine associations of concern, worry, and stress about discrimination, shootings/violence, and police brutality and exclusive and dual tobacco and cannabis use among young adults. METHODS: A prospective, racially/ethnically diverse cohort of young adults (n = 1960) living in Los Angeles, California completed a baseline survey in 2020 (age range: 19-23) and a follow-up survey in 2021. Exploratory factor analysis (EFA) was employed on nine variables assessing levels of concern, worry, and stress about societal discrimination, societal shootings/violence, and community police brutality at baseline. Past 30-day tobacco and cannabis use at follow-up was categorized as current exclusive tobacco, exclusive cannabis, and dual tobacco and cannabis (vs never/former) use based on eleven use variables. Multinomial logistic regressions estimated adjusted associations between each factor score (translated to standard deviation units) with exclusive and dual tobacco and cannabis use. RESULTS: The EFA produced four factor scores representing concern/worry/stress (i.e., distress) about community police brutality (F1), distress about societal shootings/violence (F2), and distress about societal discrimination (F3), as well as generalized stress about police brutality, shootings/violence, and discrimination (F4). F1, F2, and F3 were associated with subsequent exclusive current cannabis use, with F1 having the strongest association (OR: 1.35, 95% CI: 1.18-1.55), while only F1 (OR: 1.51, 95% CI: 1.27-1.78) was associated with dual tobacco and cannabis use. None of the factors were associated with exclusive tobacco use. CONCLUSIONS: Young adult concern, worry, and/or stress about social problems may increase risk of cannabis use with or without concurrent tobacco use 6-12 months later.

Association between ambient exposure to PM2.5 and upper aerodigestive tract cancer in Los Angeles.

Fine particulate matter (PM2.5 ) contains carcinogens similar to those generated by tobacco smoking, which may increase the risks of developing smoking-related cancers, such as upper aerodigestive track (UADT) cancers, for both smokers and never-smokers. Therefore, it is imperative to understand the relation between ambient PM2.5 exposure and risk of UADT cancers. A population-based case-control study involving 565 incident UADT cancer cases and 983 controls was conducted in Los Angeles County from 1999 to 2004. The average residential PM2.5 concentration 1 year before the diagnosis date for cases and the reference date for controls was assessed using a chemical transport model. The association between ambient PM2.5 and the UADT cancers was estimated by unconditional logistic regression, adjusting for confounders at the individual and block-group level. Stratified analyses were conducted by sex, tobacco smoking status and UADT subsites. We also assessed the interaction between PM2.5 and tobacco smoking on UADT cancers. PM2.5 concentrations were associated with an elevated odds of UADT cancers (adjusted odds ratio = 1.21 per interquartile range [4.5 µg/m3 ] increase; 95% confidence interval: 1.02, 1.44). The association between PM2.5 and UADT cancers was similar across UADT subsites, sex and tobacco smoking status. The interaction between PM2.5 and tobacco smoking on UADT cancers was approximately additive on the odds scale. The effect estimate for PM2.5 and UADT cancers was similar among never smokers. Our findings support the hypothesis that exposure to PM2.5 increases the risk of UADT cancers. Improvements in air quality may reduce the risk of UADT cancers.

Association of current substance use treatment with future reduced methamphetamine use in an observational cohort of men who have sex with men in Los Angeles.

INTRODUCTION: Methamphetamine use is highly prevalent among men who have sex with men (MSM), but knowledge of the long-term dynamics, and how they are affected by substance use treatment, is limited. This study aimed to describe trajectories of methamphetamine use among MSM, and to evaluate the impact of treatment for any kind of substance use on frequency of methamphetamine use. METHODS: This analysis used data from a cohort of MSM in Los Angeles, CA, who participated in semi-annual study visits from 2014 to 2022. The study characterized trajectories of methamphetamine use using a continuous time multistate Markov model with three states. States were defined using self-reported frequency of methamphetamine use in the past six months: frequent (daily), occasional (weekly or less), and never. The model estimated the association between receiving treatment for any kind of substance use and changes in state of frequency of methamphetamine use. RESULTS: This analysis included 2348 study visits among 285 individuals who were followed-up for an average of 4.4 years. Among participants who were in the frequent use state, 65 % (n = 26) of those who were receiving any kind of substance use treatment at a study visit had reduced their methamphetamine use at their next visit, compared to 33 % (n = 95) of those who were not receiving treatment. Controlling for age, race/ethnicity, and HIV-status, those who reported receiving current treatment for substance use were more likely to transition from occasional to no use (HR: 1.63, 95 % CI: 1.10-2.42) and frequent to occasional use (HR: 4.25, 95 % CI: 2.11-8.59) in comparison to those who did not report receiving current treatment for substance use. CONCLUSIONS: Findings from this dynamic modeling study provide a new method for assessing longitudinal methamphetamine use outcomes and add important evidence outside of clinical trials that substance use treatment may reduce methamphetamine use.

Association of the COVID-19 Pandemic on Treatment Times for ST-Elevation Myocardial Infarction: Observations from the Los Angeles County Regional System.

Previous studies have documented longer treatment times and worse outcomes for patients with ST-elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI) during the COVID-19 pandemic. The objective of the present study was to evaluate the impact of the COVID-19 pandemic on treatment times and outcomes for patients with STEMI who underwent primary PCI within a regional system of care. This was a retrospective study using data from the Los Angeles County Emergency Medical Services Agency. Data on the emergency medical service activations were abstracted for patients with STEMI from March 19, 2020 to January 31, 2021, during the COVID-19 pandemic and for the same interval the previous year. All adult patients (≥18 years) with STEMI who underwent emergent coronary angiography were included. The primary end point was the first medical contact (FMC) to device time. The secondary end points included treatment time intervals, vascular complications, need for emergent coronary artery bypass surgery, length of hospital stay, and in-hospital mortality. During the study period, 3,017 patients underwent coronary angiography for STEMI, 1,893 patients pre-COVID-19 and 1,124 patients during COVID-19 (40% lower). A total of 2,334 patients (77%) underwent PCI. During the COVID-19 period, rates of PCI were significantly lower compared with the control period (75.1% vs 78.7%, p = 0.02). FMC to device time was shorter during the COVID-19 period compared with the control period (median 77.0 vs 81.0 minutes, p = 0.004). For patients with STEMI complicated by out-of-hospital cardiac arrest, FMC to device time was similar during the COVID-19 period compared with the control period (median 95.0 [33.0] vs 100.0 [40.0] minutes, p = 0.34). Vascular complications, the need for emergent bypass surgery, length of hospital stay, and in-hospital mortality were similar between the periods. In conclusion, in this large regional system of care, we found a relatively small but significant decrease in treatment times, yet overall, similar clinical outcomes for patients with STEMI who underwent primary PCI and were treated during the COVID-19 period compared with a control period. These findings suggest that mature cardiac systems of care were able to maintain efficient care despite the challenges of the COVID-19 pandemic.

Predictors of Housing Trajectories Among Young Adults Experiencing Homelessness in Los Angeles.

Experiencing homelessness during young adulthood is associated with negative health outcomes and understanding housing trajectories of young adults experiencing homelessness may aid in the development of evidence-based public health programs designed to serve this at-risk age group. In the present study, the authors examined baseline predictors of 24-month trajectories of housing stability and unsheltered housing among a sample of 271 young adults aged 18 to 25 recruited from drop-in centers in Los Angeles. In multivariate models, the authors found that identifying as multi-racial/other and better friendship quality at baseline were associated with less steep increases in the likelihood of stable housing over time. Being employed at baseline was associated with a less steep decrease in the probability of being unsheltered over time, while illicit drug use days associated with a steeper decrease in the probability of being unsheltered over time. Continued research is needed to establish important factors determining young adults' long-term housing trajectories in the effort to promote greater access and engagement with housing services.

Differences in presentation, treatment, and outcomes among minority head and neck cancer patient groups in Los Angeles County.

IMPORTANCE: While minorities represent around 20 % of all HNC patients, these demographics are largely understudied. Furthermore, trends in national studies may not always be fully replicated in locoregional populations, indicating a need for more nuanced study. OBJECTIVE: To better understand our patient population, we sought to understand differences in presentation, management, and outcome between Caucasians and minority groups with HNC. DESIGN: Retrospective cohort analysis of the Los Angeles County Surveillance Epidemiology and End Results (SEER) database. SETTING: Los Angeles County. PARTICIPANTS: All patients in Los Angeles County diagnosed with cancer of the head and neck from January 1, 1988 to December 31, 2018. MAIN OUTCOMES AND MEASURES: The primary outcome in our study was significant differences between racial and ethnic groups in age of diagnosis, sex, socioeconomic quintile, insurance status, stage at diagnosis, treatment modality, time to first treatment, and cancer-specific cause of death. RESULTS: Our 18,510-patient cohort was largely male (64.35 %), white (69.57 %), and were on average 62.84 years old (SD = 20.07). When stratifying patients by race and ethnicity, significant differences were found in average age at diagnosis, sex, socioeconomic quintile, insurance status, and stage at diagnosis, treatment modalities utilized, and time to first treatment (all p < 0.001). Relative to all other head and neck patients, minority groups were significantly younger, had lower proportions of male patients, were less likely to pursue surgery, were more likely to pursue chemotherapy or radiation, and endorsed longer time to first treatment (all p < 0.001). The distribution of socioeconomic quintile (all p < 0.001), insurance status (all p < 0.001), and stage at diagnosis (all p < 0.05) also significantly varied between minority and reference groups. Only African Americans exhibited significantly higher rates of cancer-specific cause of death relative to non-African Americans (p < 0.001). CONCLUSIONS AND RELEVANCE: Pervasive socioeconomic disparities between Caucasian HNC patients and those of other minority racial and ethnic groups in Los Angeles County that likely and significantly impact the diagnosis and management of HNC and its resultant outcomes. We encourage others to similarly examine their local populations to tailor the quality of care provided to patients.

Maternal dietary patterns and placental outcomes among pregnant women in Los Angeles.

INTRODUCTION: Epidemiological studies have linked prenatal maternal diet to fetal growth, but whether diet affects placental outcomes is poorly understood. METHODS: We collected past month dietary intake from 148 women in mid-pregnancy enrolled at University of California Los Angeles (UCLA) antenatal clinics from 2016 to 2019. We employed the food frequency Diet History Questionnaire II and generated the Healthy Eating Index-2015 (HEI-2015), the Alternate Healthy Eating Index for Pregnancy (AHEI-P), and the Alternate Mediterranean Diet (aMED). We conducted T2-weighted magnetic resonance imaging (MRI) in mid-pregnancy (1st during 14-17 and 2nd during 19-24 gestational weeks) to evaluate placental volume (cm3) and we measured placenta weight (g) at delivery. We estimated change and 95 % confidence interval (CI) in placental volume and associations of placenta weight with all dietary index scores and diet items using linear regression models. RESULTS: Placental volume in mid-pregnancy was associated with an 18.9 cm3 (95 % CI 5.1, 32.8) increase per 100 gestational days in women with a higher HEI-2015 (≥median), with stronger results for placentas of male fetuses. We estimated positive associations between placental volume at the 1st and 2nd MRI and higher intake of vegetables, high-fat fish, dairy, and dietary intake of B vitamins. A higher aMED (≥median) score was associated with a 40.5 g (95 % CI 8.5, 72.5) increase in placenta weight at delivery, which was mainly related to protein intake. DISCUSSION: Placental growth represented by volume in mid-pregnancy and weight at birth is influenced by the quality and content of the maternal diet.

School-Located Vaccine Clinics: An Effective Strategy for Expanding Access to COVID-19 Vaccines in Los Angeles County.

A key component of decreasing severe disease, hospitalizations, and death due to COVID-19 has been increasing vaccine accessibility to residents in communities where access to health care is poor and residents are at increased risk of poor health outcomes. Driven by the expansive geography and diverse population it serves, the Los Angeles County Department of Public Health built an extensive school vaccination network by partnering with the county's roughly 3000 schools and vaccine providers. We report on the process of building this network and its impact on vaccination coverage. We describe a unique equity metric (HPI+) that used a combination of the Healthy Places Index (HPI) and COVID-19 transmission and vaccination data to prioritize school-located vaccination efforts. More than 328 991 doses of COVID-19 vaccine were administered at 1050 schools in Los Angeles County from April 15, 2021, through June 18, 2022. Nearly 10% of all doses administered to children aged 5-11 years in Los Angeles County were at school-located vaccine clinics. Most vaccine clinic days (77.3%) were held at schools in HPI+ zip codes. Most doses (68.3%) were administered in HPI+ regions and to people aged ≥12 years (70.3%). Vaccinating the community at schools is an effective public health intervention; however, increased outreach efforts were required in HPI+ regions to ensure equitable access to vaccines. This case study can be used to replicate public health interventions using schools to support access to health care services for students and the surrounding community.

Fine Particulate Matter Metal Composition, Oxidative Potential, and Adverse Birth Outcomes in Los Angeles.

BACKGROUND: Although many studies have linked prenatal exposure to PM2.5 to adverse birth outcomes, little is known about the effects of exposure to specific constituents of PM2.5 or mechanisms that contribute to these outcomes. OBJECTIVES: Our objective was to investigate effects of oxidative potential and PM2.5 metal components from non-exhaust traffic emissions, such as brake and tire wear, on the risk of preterm birth (PTB) and term low birth weight (TLBW). METHODS: For a birth cohort of 285,614 singletons born in Los Angeles County, California, in the period 2017-2019, we estimated speciated PM2.5 exposures modeled from land use regression with cokriging, including brake and tire wear related metals (barium and zinc), black carbon, and three markers of oxidative potential (OP), including modeled reactive oxygen species based on measured iron and copper (ROS), OH formation (OPOH), and dithiothreitol (DTT) loss (OPDTT). Using logistic regression, we estimated odds ratios (OR) and 95% confidence intervals (CI) for PTB and TLBW with speciated PM2.5 exposures and PM2.5 mass as continuous variables scaled by their interquartile range (IQR). RESULTS: For both metals and oxidative potential metrics, we estimated increased risks for PTB (ORs ranging from 1.01 to 1.03) and TLBW (ORs ranging from 1.02 to 1.05) per IQR exposure increment that were robust to adjustment for PM2.5 mass. Associations for PM2.5 mass, black carbon, metal components, and oxidative potential (especially ROS and OPOH) with adverse birth outcomes were stronger in Hispanic, Black, and mixed-race or Native American women. DISCUSSION: Our results indicate that exposure to PM2.5 metals from brake and tire wear and particle components that contribute to oxidative potential were associated with an increased risk of PTB and TLBW in Los Angeles County, particularly among Hispanic, Black, and mixed-race or Native American women. Thus, reduction of PM2.5 mass only may not be sufficient to protect the most vulnerable pregnant women and children from adverse effects due to traffic source exposures. https://doi.org/10.1289/EHP12196.

Association of neighborhood gentrification and residential moves with hypertension and diabetes control in Los Angeles County, 2014-2019: A retrospective cohort study.

OBJECTIVE: To examine whether gentrification exposure is associated with future hypertension and diabetes control. METHODS: Linking records from an integrated health care system to census-tract characteristics, we identified adults with hypertension and/or diabetes residing in stably low-SES census tracts in 2014 (n = 69,524). We tested associations of census tract gentrification occurring between 2015 and 2019 with participants' disease control in 2019. Secondary analyses considered the role of residential moves (possible displacement), race and ethnicity, and age. RESULTS: Gentrification exposure was associated with improved odds of hypertension control (aOR: 1.08; 95% CI: 1.00, 1.17), especially among non-Hispanic Whites and adults >65 years. Gentrification was not associated with diabetes control overall, but control improved in the Hispanic subgroup. Disease control was similar regardless of residential moves in the overall sample, but disparate associations emerged in models stratified by race and ethnicity. CONCLUSIONS: Residents of newly gentrifying neighborhoods may experience modestly improved odds of hypertension and/or diabetes control, but associations may differ across population subgroups. POLICY IMPLICATIONS: Gentrification may support-or at least not harm-cardiometabolic health for some residents. City leaders and health systems could partner with impacted communities to ensure that neighborhood development meets the goals and health needs of all residents and does not exacerbate health disparities.

Countering Mpox Vaccination Disparities in Los Angeles County, California, May-December 2022.

Providing equitable access to vaccines for individuals at risk for mpox was critical for containing the 2022 mpox outbreak in Los Angeles County, California. Eligible non-Hispanic Black/African American and Latinx individuals had lower vaccine uptake than did non-Hispanic White individuals, despite having higher mpox case rates. Strategies to address disparities in vaccine uptake included using familiar messaging technology to reach individuals at risk for mpox, using partnerships with community-based organizations to raise mpox awareness, and bringing vaccines to locations convenient to at-risk individuals to improve access. (Am J Public Health. 2023;113(12):1258-1262. https://doi.org/10.2105/AJPH.2023.307409).

PrEP Use and HIV Incidence Among Youth At-Risk for HIV Infection in Los Angeles and New Orleans: Findings From ATN 149.

INTRODUCTION: Expanding HIV pre-exposure prophylaxis (PrEP) use is key to goals for lowering new HIV infections in the U.S. by 90% between 2022 and 2030. Unfortunately, youth aged 16-24 have the lowest PrEP use of any age group and the highest HIV incidence rates. METHODS: To examine the relationship between HIV seroconversion and PrEP uptake, adherence, and continuity, we used survival analysis and multivariable logistic regression on data of 895 youth at-risk for HIV infection enrolled in Adolescent Trials Network for HIV Medicine protocol 149 in Los Angeles and New Orleans, assessed at 4-month intervals over 24 months. RESULTS: The sample was diverse in race/ethnicity (40% Black, 28% Latine, 20% White). Most participants (79%) were cis-gender gay/bisexual male but also included 7% transgender female and 14% trans masculine and nonbinary youth. Self-reported weekly PrEP adherence was high (98%). Twenty-seven participants acquired HIV during the study. HIV incidence among PrEP users (3.12 per 100 person year [PY]) was higher than those who never used PrEP (2.53/100 PY). The seroconversion incidence was highest among PrEP users with discontinuous use (3.36/100 PY). If oral PrEP users were adherent using 2-monthly long-acting injectables, our estimate suggests 2.06 infections per 100 PY could be averted. CONCLUSIONS: Discontinuous use of PrEP may increase risk of HIV acquisition among youth at higher risk for HIV infection and indications for PrEP. Thus, to realize the promise of PrEP in reducing new HIV infections, reducing clinical burdens for PrEP continuation are warranted.

Fleaborne Typhus-Associated Deaths - Los Angeles County, California, 2022.

Fleaborne typhus (also known as murine typhus), a widely distributed vectorborne zoonosis caused by Rickettsia typhi, is a moderately severe, but infrequently fatal illness; among patients who receive doxycycline, the case-fatality rate is <1%. Fleaborne typhus is a mandated reportable condition in California. Reported fleaborne typhus cases in Los Angeles County have been increasing since 2010, with the highest number (171) reported during 2022. During June-October 2022, Los Angeles County Department of Public Health learned of three fleaborne typhus-associated deaths. This report describes the clinical presentation, illness course, and methods used to diagnose fleaborne typhus in these three cases. Severe fleaborne typhus manifestations among these cases included hemophagocytic lymphohistiocytosis, a rare immune hyperactivation syndrome that can occur in the infection setting; myocarditis; and septic shock with disseminated intravascular coagulation. Increased health care provider and public health awareness of the prevalence and severity of fleaborne typhus and of the importance of early doxycycline therapy is essential for prevention and treatment efforts.

COVID-19-Related Emergency Department Visits Among Undocumented Patients in Los Angeles County.

Undocumented immigrants may be vulnerable to poor COVID-19 outcomes, but also may be less likely to seek medical care. To our knowledge, there have not been any investigations of potential COVID-19 disparities by immigration status. We analyzed emergency department (ED) visit data from March 20, 2020 to September 30, 2020 among patients in a safety-net hospital in Los Angeles County (n=30,023). We compared the probability of COVID-19-related ED visits between undocumented immigrants and Medi-Cal patients. We also examined differences in these comparisons over time. Undocumented patients had higher odds of COVID-19-related ED visits than Medi-Cal patients (OR: 1.41, 95% CI: 1.24-1.60) for all months in the study period except September. Even in the earliest days of the pandemic, undocumented patients were more likely than Medi-Cal patients to have a COVID-19-related ED visit. Additional analyses suggest this was likely because of higher COVID-19 exposure rather than differences in ED utilization.

Ecological risk and protective factors for food insufficiency in Los Angeles County during the COVID-19 pandemic.

OBJECTIVE: The COVID-19 pandemic increased food insufficiency: a severe form of food insecurity. Drawing on an ecological framework, we aimed to understand factors that contributed to changes in food insufficiency from April to December 2020, in a large urban population hard hit by the pandemic. DESIGN: We conducted internet surveys every 2 weeks in April-December 2020, including a subset of items from the Food Insecurity Experience Scale. Longitudinal analysis identified predictors of food insufficiency, using fixed effects models. SETTING: Los Angeles County, which has a diverse population of 10 million residents. PARTICIPANTS: A representative sample of 1535 adults in Los Angeles County who are participants in the Understanding Coronavirus in America tracking survey. RESULTS: Rates of food insufficiency spiked in the first year of the pandemic, especially among participants living in poverty, in middle adulthood and with larger households. Government food assistance from the Supplemental Nutrition Assistance Program was significantly associated with reduced food insufficiency over time, while other forms of assistance such as help from family and friends or stimulus funds were not. CONCLUSIONS: The findings highlight that during a crisis, there is value in rapidly monitoring food insufficiency and investing in government food benefits.

Disparities in COVID-19 Disease Incidence by Income and Vaccination Coverage - 81 Communities, Los Angeles, California, July 2020-September 2021.

COVID-19 has disproportionately affected socially vulnerable communities characterized by lower income, lower education attainment, and higher proportions of minority populations, among other factors (1-4). Disparities in COVID-19 incidence and the impact of vaccination on incidence disparities by community income were assessed among 81 communities in Los Angeles, California. Median community vaccination coverage and COVID-19 incidence were calculated across household income strata using a generalized linear mixed effects model with Poisson distribution during three COVID-19 surge periods: two before vaccine availability (July 2020 and January 2021) and the third after vaccines became widely available in April 2021 (September 2021). Adjusted incidence rate ratios (aIRRs) during the peak month of each surge were compared across communities grouped by median household income percentile. The aIRR between communities in the lowest and highest median income deciles was 6.6 (95% CI = 2.8-15.3) in July 2020 and 4.3 (95% CI = 1.8-9.9) in January 2021. However, during the September 2021 surge that occurred after vaccines became widely availabile, model estimates did not identify an incidence disparity between the highest- and lowest-income communities (aIRR = 0.80; 95% CI = 0.35-1.86). During this surge, vaccination coverage was lowest (59.4%) in lowest-income communities and highest (71.5%) in highest-income communities (p<0.001). However, a significant interaction between income and vaccination on COVID-19 incidence (p<0.001) indicated that the largest effect of vaccination on disease incidence occured in the lowest-income communities. A 20% increase in community vaccination was estimated to have resulted in an additional 8.1% reduction in COVID-19 incidence in the lowest-income communities compared with that in the highest-income communities. These findings highlight the importance of improving access to vaccination and reducing vaccine hesitancy in underserved communities in reducing disparities in COVID-19 incidence.