ABSTRACT
BO_SCPLOWACKGROUNDC_SCPLOWPrisons and jails are high-risk settings for Covid-19 transmission, morbidity, and mortality. We evaluate protection conferred by prior infection and vaccination against the SARS-CoV-2 Omicron variant within the California state prison system. MO_SCPLOWETHODSC_SCPLOWWe employed a test-negative design to match resident and staff cases during the Omicron wave (December 24, 2021--April 14, 2022) to controls according to a cases test-week as well as demographic, clinical, and carceral characteristics. We estimated protection against infection using conditional logistic regression, with exposure status defined by vaccination, stratified by number of mRNA doses received, and prior infection, stratified by periods before or during Delta variant predominance. RO_SCPLOWESULTSC_SCPLOWWe matched 15,783 resident and 8,539 staff cases to 180,169 resident and 90,409 staff controls. Among cases, 29.7% and 2.2% were infected before or during the emergence of the Delta variant, respectively; 30.6% and 36.3% were vaccinated with two or three doses, respectively. Estimated protection from Omicron infection for two and three doses were 14.9% (95% Confidence Interval [CI], 12.3--19.7%) and 43.2% (42.2--47.4%) for those without known prior infections, 47.8% (95% CI, 46.6--52.8%) and 61.3% (95% CI, 60.7--64.8%) for those infected before the emergence of Delta, and 73.1% (95% CI, 69.8--80.1%) and 86.8% (95% CI, 82.1--92.7) for those infected during the period of Delta predominance. CO_SCPLOWONCLUSIONC_SCPLOWA third mRNA dose provided significant, additional protection over two doses, including among individuals with prior infection. Our findings suggest that vaccination should remain a priority--even in settings with high levels of transmission and prior infection.
ABSTRACT
The potential for bias in non-representative, large-scale, low-cost survey data can limit their utility for population health measurement and public health decision-making. We developed a multi-step regression framework to bias-adjust vaccination coverage predictions from the large-scale US COVID-19 Trends and Impact Survey that included post-stratification to the American Community Survey and secondary normalization to an unbiased reference indicator. As a case study, we applied this framework to generate county-level predictions of long-run vaccination coverage among children ages 5 to 11 years. Our vaccination coverage predictions suggest a low ceiling on long-term national coverage (46%), detect substantial geographic heterogeneity (ranging from 11% to 91% across counties in the US), and highlight widespread disparities in the pace of scale-up in the three months following Emergency Use Authorization of COVID-19 vaccination for 5 to 11 year-olds. Generally, our analysis demonstrates an approach to leverage differing strengths of multiple sources of information to produce estimates on the time-scale and geographic-scale necessary for proactive decision-making. The utility of large-scale, low-cost survey data for improving population health measurement is amplified when these data are combined with other representative sources of data.
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To distinguish waning of vaccine responses from differential variant protection, we performed a test-negative case-control analysis during a Delta variant-dominant period in Californias prisons. We found that infection odds increased each 28-day period post-vaccination, reaching 3.4-fold (residents) to 4.7-fold (staff) increased odds of infection after 180 days.
ABSTRACT
BackgroundPrisons are high-risk environments for Covid-19. Vaccination levels among prison staff remain troublingly low - lower than levels among residents and members of the surrounding community. The situation is troubling because prison staff are a key vector for Covid-19 transmission. ObjectiveTo assess patterns and timing of staff vaccination in California state prisons and identify individual- and community-level factors associated with being unvaccinated. DesignWe calculated fractions of prison staff and incarcerated residents in California state prisons who remained unvaccinated. Adjusted analyses identified demographic, community, and peer factors associated with vaccination uptake among staff. SettingCalifornia Department of Corrections and Rehabilitation prisons. ParticipantsCustody and healthcare staff who worked in direct contact with residents. Main Outcomes and MeasuresRemaining unvaccinated through June 30, 2021. ResultsA total of 26% of custody staff and 52% of healthcare staff took [≥]1 dose in the first two months of vaccine offer; uptake stagnated thereafter. By June 30, 2021, 61% of custody and 37% of healthcare staff remained unvaccinated. Remaining unvaccinated was positively associated with younger age, prior Covid-19, residing in a community with relatively low vaccination rates, and sharing shifts with co-workers who had relatively low vaccination rates. Conclusions and RelevanceVaccine uptake among prison staff in California in regular contact with incarcerated residents has plateaued at levels that pose ongoing risks--both of further outbreaks in the prisons and transmission into surrounding communities. Staff decisions to forego vaccination appear to be complex and multifactorial. Achieving safe levels of vaccine protection among frontline staff may necessitate requiring vaccination as condition of employment.
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BackgroundPrisons and jails are high-risk settings for COVID-19 transmission, morbidity, and mortality. COVID-19 vaccines may substantially reduce these risks, but evidence is needed of their effectiveness for incarcerated people, who are confined in large, risky congregate settings. MethodsWe conducted a retrospective cohort study to estimate effectiveness of mRNA vaccines, BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna), against confirmed SARS-CoV-2 infections among incarcerated people in California prisons from December 22, 2020 through March 1, 2021. The California Department of Corrections and Rehabilitation provided daily data for all prison residents including demographic, clinical, and carceral characteristics, as well as COVID-19 testing, vaccination status, and outcomes. We estimated vaccine effectiveness using multivariable Cox models with time-varying covariates that adjusted for resident characteristics and infection rates across prisons. FindingsAmong 60,707 residents in the cohort, 49% received at least one BNT162b2 or mRNA-1273 dose during the study period. Estimated vaccine effectiveness was 74% (95% confidence interval [CI], 64-82%) from day 14 after first dose until receipt of second dose and 97% (95% CI, 88-99%) from day 14 after second dose. Effectiveness was similar among the subset of residents who were medically vulnerable (74% [95% CI, 62-82%] and 92% [95% CI, 74-98%] from 14 days after first and second doses, respectively), as well as among the subset of residents who received the mRNA-1273 vaccine (71% [95% CI, 58-80%] and 96% [95% CI, 67-99%]). ConclusionsConsistent with results from randomized trials and observational studies in other populations, mRNA vaccines were highly effective in preventing SARS-CoV-2 infections among incarcerated people. Prioritizing incarcerated people for vaccination, redoubling efforts to boost vaccination and continuing other ongoing mitigation practices are essential in preventing COVID-19 in this disproportionately affected population. FundingHorowitz Family Foundation, National Institute on Drug Abuse, Centers for Disease Control and Prevention, National Science Foundation, Open Society Foundation, Advanced Micro Devices.
ABSTRACT
BackgroundResidents of correctional facilities have experienced disproportionately higher rates of SARS-CoV-2 infection and Covid-19-related mortality. To protect against outbreaks, many prisons and jails imposed heavy restrictions on in-person activities, which are now beginning to lift. Uncertainty surrounds the safety of these moves. Methods and FindingsWe obtained system-wide resident-day level data for the California state prison system, the nations third largest. We used the data to develop a transmission-dynamic stochastic microsimulation model that projects the impact of various policy scenarios on risks of SARS-CoV-2 infections and related hospitalization among residents after an initial infection is introduced to a prison. The policy scenarios vary according to levels of vaccine coverage, baseline immunity, resumption of activities, and use of non-pharmaceutical interventions (e.g., masking, physical distancing). The analyses were conducted across 5 types of prisons that differed in their residential layouts, security levels, and resident demographics. If a viral variant is introduced into a prison that has resumed pre-2020 contact levels, has moderate vaccine coverage, and has no baseline immunity, 23-74% of residents are expected to be infected over 200 days. High vaccination coverage coupled with use of non-pharmaceutical measures reduces cumulative infections to 2-54% of residents. In prisons consisting mostly of dormitory housing, even with high vaccine coverage and non-pharmaceutical interventions, resumption of in-person activities is associated with substantial risk, unless there is high baseline immunity (e.g., [≥]50%) from prior outbreaks. In prisons consisting mostly of cell housing, <10% of residents are expected to become infected, even with no baseline immunity. However, hospitalization risks are substantial in prisons that house medically vulnerable populations, even for prisons consisting mostly of cells. Risks of large outbreaks are substantially higher if there is continued introduction of infections into a prison. Some findings may not be transportable to other carceral settings, and our assumptions regarding viral variants will not be accurate for all variants. ConclusionsBalancing the benefits of resuming normal in-person activities against the risks of Covid-19 outbreaks is a difficult challenge for correctional systems. The policy choices are not strictly binary. To protect against viral variants, prisons should focus on achieving both high vaccine coverage and maintaining widespread use of non-pharmaceutical interventions. With both in place, some prisons, especially those with lower room occupancy that have already had large outbreaks, could safely resume in-person activities, while continuing testing and measures to protect the medically-vulnerable.
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BackgroundAs of April 19, all adults aged 16 years and older are eligible for COVID-19 vaccination. Unequal vaccination rates across racial/ethnic groups may compound existing disparities in cases, hospitalizations, and deaths among Black, Indigenous, and Hispanic communities. MethodsFrom state websites, we extracted shares of people receiving [≥]1 vaccine dose, stratified by age and separately by race/ethnicity, through March 31, 2021. Combining these data with demographic data from the American Community Survey, we estimated relative uptake rates by race/ethnicity within each state as the observed share of vaccinations for a racial/ethnic group, divided by the expected share if uptake across racial/ethnic groups within each age group were proportional to population size, an approach that allowed us to control for historical age-based eligibility. We modeled vaccination scale-up within each census tract in a state under three scenarios: 1) a scenario in which unequal uptake rates persist, 2) a scenario in which uptake rates are equalized across race/ethnicity groups over six weeks, and 3) a scenario in which uptake is equalized and states employ place-based allocation strategies that prioritizes disadvantaged census tracts. ResultsWhite adults received a disproportionate share of vaccinations compared to Black and Hispanic adults through March 31, 2021. Across states, relative uptake rates, adjusted for eligible population size, were a median 1.3 (IQR, 1.2-1.4) times higher for White compared to Black adults, and a median 1.4 (IQR, 1.2-1.8) times higher for White compared to Hispanic adults. Projecting vaccination coverage under persistence of current disparities in uptake, we found that Black and Hispanic populations would reach 75% coverage among adults almost one month later than White populations. In alternative scenarios, we found that interventions to equalize uptake rates across racial/ethnic groups could narrow but not erase these gaps, and that geographic targeting of vaccine doses to disadvantaged communities may be needed to produce a more equitable convergence of coverage by July. DiscussionInterventions are urgently needed to eliminate disparities in COVID-19 vaccination rates. Eliminating access barriers and increasing vaccine confidence among marginalized populations can narrow gaps in coverage. Combining these interventions with place-based allocation strategies can accelerate vaccination in disadvantaged communities, who have borne a disproportionate burden from COVID-19.
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BackgroundCorrectional institutions nationwide are seeking to mitigate Covid-19-related risks. ObjectiveTo quantify changes to Californias prison population since the pandemic began and identify risk factors for Covid-19 infection. DesignWe described residents demographic characteristics, health status, Covid-19 risk scores, room occupancy, and labor participation. We used Cox proportional hazard models to estimate the association between rates of Covid-19 infection and room occupancy and out-of-room labor, respectively. SettingCalifornia state prisons (March 1-October 10, 2020). ParticipantsResidents of California state prisons. MeasurementsChanges in the incarcerated populations size, composition, housing, and activities. For the risk factor analysis, the exposure variables were room type (cells vs dormitories) and labor participation (any room occupant participating in the prior 2 weeks) and the outcome variable was incident Covid-19 case rates. ResultsThe incarcerated population decreased 19.1% (119,401 to 96,623) during the study period.On October 10, 2020, 11.5% of residents were aged [≥]60, 18.3% had high Covid-19 risk scores, 31.0% participated in out-of-room labor, and 14.8% lived in rooms with [≥]10 occupants. Nearly 40% of residents with high Covid-19 risk scores lived in dormitories. In 9 prisons with major outbreaks (6,928 rooms; 21,750 residents), dormitory residents had higher infection rates than cell residents (adjusted hazard ratio [AHR], 2.51 95%CI, 2.25-2.80) and residents of rooms with labor participation had higher rates than residents of other rooms (AHR, 1.56; 95%CI, 1.39-1.74). LimitationsInability to measure density of residents living conditions or contact networks among residents and staff. ConclusionDespite reductions in room occupancy and mixing, California prisons still house many medically vulnerable residents in risky settings. Reducing risks further requires a combination of strategies, including rehousing, decarceration, and vaccination. Funding SourcesHorowitz Family Foundation; National Institute on Drug Abuse; National Science Foundation Graduate Research Fellowship; Open Society Foundations.
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BackgroundWith more than 20 million residents, Mexico City Metropolitan Area (MCMA) has the largest number of Covid-19 cases in Mexico and is at risk of exceeding its hospital capacity in late December 2020. MethodsWe used SC-COSMO, a dynamic compartmental Covid-19 model, to evaluate scenarios considering combinations of increased contacts during the holiday season, intensification of social distancing, and school reopening. Model parameters were derived from primary data from MCMA, published literature, and calibrated to time-series of incident confirmed cases, deaths, and hospital occupancy. Outcomes included projected confirmed cases and deaths, hospital demand, and magnitude of hospital capacity exceedance. FindingsFollowing high levels of holiday contacts even with no in-person schooling, we predict that MCMA will have 1{middle dot}0 million (95% prediction interval 0{middle dot}5 - 1{middle dot}7) additional Covid-19 cases between December 7, 2020 and March 7, 2021 and that hospitalizations will peak at 35,000 (14,700 - 67,500) on January 27, 2021, with a >99% chance of exceeding Covid-19-specific capacity (9,667 beds). If holiday contacts can be controlled, MCMA can reopen in-person schools provided social distancing is increased with 0{middle dot}5 million (0{middle dot}2 - 1{middle dot}0) additional cases and hospitalizations peaking at 14,900 (5,600 - 32,000) on January 23, 2021 (77% chance of exceedance). InterpretationMCMA must substantially increase Covid-19 hospital capacity under all scenarios considered. MCMAs ability to reopen schools in mid-January 2021 depends on sustaining social distancing and that contacts during the end-of-year holiday were well controlled. FundingSociety for Medical Decision Making, Gordon and Betty Moore Foundation, and Wadhwani Institute for Artificial Intelligence Foundation. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSAs of mid-December 2020, Mexico has the twelfth highest incidence of confirmed cases of Covid-19 worldwide and its epidemic is currently growing. Mexicos case fatality ratio (CFR) - 9{middle dot}1% - is the second highest in the world. With more than 20 million residents, Mexico City Metropolitan Area (MCMA) has the highest number and incidence rate of Covid-19 confirmed cases in Mexico and a CFR of 8{middle dot}1%. MCMA is nearing its current hospital capacity even as it faces the prospect of increased social contacts during the 2020 end-of-year holidays. There is limited Mexico-specific evidence available on epidemic, such as parameters governing time-dependent mortality, hospitalization and transmission. Literature searches required supplementation through primary data analysis and model calibration to support the first realistic model-based Covid-19 policy evaluation for Mexico, which makes this analysis relevant and timely. Added value of this studyStudy strengths include the use of detailed primary data provided by MCMA; the Bayesian model calibration to enable evaluation of projections and their uncertainty; and consideration of both epidemic and health system outcomes. The model projects that failure to limit social contacts during the end-of-year holidays will substantially accelerate MCMAs epidemic (1{middle dot}0 million (95% prediction interval 0{middle dot}5 - 1{middle dot}7) additional cases by early March 2021). Hospitalization demand could reach 35,000 (14,700 - 67,500), with a >99% chance of exceeding current capacity (9,667 beds). Controlling social contacts during the holidays could enable MCMA to reopen in-person schooling without greatly exacerbating the epidemic provided social distancing in both schools and the community were maintained. Under all scenarios and policies, current hospital capacity appears insufficient, highlighting the need for rapid capacity expansion. Implications of all the available evidenceMCMA officials should prioritize rapid hospital capacity expansion. MCMAs ability to reopen schools in mid-January 2021 depends on sustaining social distancing and that contacts during the end-of-year holiday were well controlled.
ABSTRACT
Without vaccines, non-pharmaceutical interventions have been the most widely used approach to controlling the spread of COVID-19 epidemics. Various jurisdictions have implemented public health orders as a means of reducing effective contacts and controlling their local epidemics. Multiple studies have examined the effectiveness of various orders (e.g. use of face masks) for epidemic control. However, orders occur at different timings across jurisdictions and some orders on the same topic are stricter than others. We constructed a county-level longitudinal data set of more than 2,400 public health orders issues by California and its 58 counties pertaining to its 40 million residents. First, we describe methods used to construct the dataset that enables the characterization of the evolution over time of California state- and county-level public health orders dealing with COVID-19 from January 1, 2020 through June 30, 2021. Public health orders are both an interesting and important outcome in their own right and also a key input into analyses looking at how such orders may impact COVID-19 epidemics. To construct the dataset, we developed and executed a search strategy to identify COVID-19 public health orders over this time period for all relevant jurisdictions. We characterized each identified public health order in terms of the timing of when it was announced, went into effect and (potentially) expired. We also adapted an existing schema to describe the topic(s) each public health order dealt with and the level of stricture each imposed, applying it to all identified orders. Finally, as an initial assessment, we examined the patterns of public health orders within and across counties, focusing on the timing of orders, the rate of increase and decrease in stricture, and on variation and convergence of orders within regions.
