Barriers to initial COVID-19 booster among U.S. adults who completed a primary vaccine series in the CHASING COVID cohort, September 2021 - October 2022.

It is crucial to understand factors associated with COVID-19 booster uptake in the U.S. given the updated COVID-19 vaccine recommendations. Using data from a national prospective cohort (N=4,616) between September 2021-October 2022, we examined socioeconomic, demographic, and behavioral factors of initial booster uptake among participants fully-vaccinated with the primary COVID-19 vaccines series. Cox proportional hazards models were used to estimate the associations of each factor with time to initial booster uptake. Most participants (86.5%) reported receiving their initial booster. After adjusting for age, race/ethnicity, education, region, and employment, participants with greater risk for severe COVID-19 had similar booster uptake compared with those with lower risk (aHR: 1.04; 95% CI: 0.95, 1.14). Participants with greater barriers to healthcare (aHR: 0.89; 95% CI: 0.84, 0.96), food insecurity (aHR: 0.82; 95% CI: 0.75, 0.89), and housing instability (aHR: 0.81; 95% CI: 0.73, 0.90) were less likely to report receiving initial booster compared with those without those barriers. Factors motivating the decision to vaccinate changed from safety-related concerns for the primary series to perceived need for the booster. It is key to address economic and health access barriers to achieve equitable COVID-19 vaccine uptake and continued protection against COVID-19.

Association between pertussis vaccination coverage and other sociodemographic factors and pertussis incidence using surveillance data.

Routine vaccination with pertussis vaccines has been successful in driving down pertussis mortality and morbidity globally. Despite high vaccination coverage, countries such as Australia, USA, and UK have experienced increase in pertussis activity over the last few decades. This may be due to local pockets of low vaccination coverage that result in persistence of pertussis in the population and occasionally lead to large outbreaks. The objective of this study was to characterize the association between pertussis vaccination coverage and sociodemographic factors and pertussis incidence at the school district level in King County, Washington, USA. We used monthly pertussis incidence data for all ages reported to the Public Health Seattle and King County between January 1, 2010 and December 31, 2017 to obtain school district level pertussis incidence. We obtained immunization data from the Washington State Immunization Information System to estimate school-district level vaccination coverage as proportion of 19-35 month old children fully vaccinated with ≥4 doses of the Diphtheria-Tetanus-acellular-Pertussis (DTaP) vaccine in a school district. We used two methods to quantify the effects of vaccination coverage on pertussis incidence: an ecological vaccine model and an endemic-epidemic model. Even though the effect of vaccination is modeled differently in the two approaches, both models can be used to estimate the association between vaccination coverage and pertussis incidence. Using the ecological vaccine model, we estimated the vaccine effectiveness of 4 doses of Diphtheria-Tetanus-acellular-Pertussis vaccine to be 83% (95% credible interval: 63%, 95%). In the endemic-epidemic model, under-vaccination was statistically significantly associated with epidemic risk of pertussis (adjusted Relative Risk, aRR: 2.76; 95% confidence interval: 1.44, 16.6). Household size and median income were statistically significantly associated with endemic pertussis risk. The endemic-epidemic model suffers from ecological bias, whereas the ecological vaccine model provides less biased and more interpretable estimates of epidemiological parameters, such as DTaP vaccine effectiveness, for each school district.

Psychosocial Stressors and Maternal Mental Health in the U.S. During the First Wave of the COVID-19 Pandemic: A Cross-Sectional Analysis.

OBJECTIVES: The COVID pandemic has had widespread impacts on maternal mental health. This research aims to examine the relationship between psychosocial stressors and symptoms of depression and anxiety and the extent to which emotional support or resilient coping moderates the relationship between psychosocial stressors and maternal mental health during the first wave of the COVID pandemic. METHODS: This analysis includes data collected in October and November 2020 from a geographically and sociodemographically diverse sample of 776 mothers in the U.S. with children ≤ 18 years of age. Log binomial models were used to estimate the association between moderate or severe symptoms of anxiety and depression and psychosocial stressors. RESULTS: Symptoms of moderate or severe anxiety and depression were reported by 37.5% and 37.6% of participants, respectively. Moderate (aRR 2.76 [95% CI 1.87, 4.07]) and high (aRR 4.95 [95% CI 3.40, 7.20]) levels of perceived stress were associated with greater risk of moderate or severe anxiety symptoms. Moderate and high levels of parental burnout were also associated with greater prevalence of moderate or severe anxiety symptoms in multivariable models. Results were similar when examining the relationship among stress, parental burnout, and depressive symptoms. Neither resilient coping nor social support modified the relationship between psychosocial stressors and mental health. CONCLUSIONS FOR PRACTICE: Evidence-based strategies to reduce stress and parental burnout and improve the mental health of mothers are urgently needed. Strategies focused on bolstering coping and social support may be insufficient to improve maternal mental health during acute public health emergencies.

Effectiveness of Covid-19 vaccines against symptomatic and asymptomatic SARS-CoV-2 infections in an urgent care setting.

BACKGROUND: It is critical to monitor changes in vaccine effectiveness against COVID-19 outcomes for various vaccine products in different population subgroups. METHODS: We conducted a retrospective study in patients ≥12 years who underwent testing for SARS-CoV-2 virus from April 14 through October 25, 2021, at urgent care centers in the New York metropolitan area. Patients self-reported vaccination status at the time of testing. We used a test-negative design to estimate vaccine effectiveness (VE) by comparing odds of a positive test for SARS-CoV-2 infection among vaccinated (n = 474,805), partially vaccinated (n = 87,834), and unvaccinated (n = 369,333) patients, adjusted for demographic factors and calendar time. RESULTS: VE against symptomatic infection after 2 doses of mRNA vaccine was 96% (95% Confidence Interval: 95%, 97%) in the pre-delta period and reduced to 79% (95% CI: 77%, 81%) in the delta period. In the delta period, VE for 12-15-year-olds (85%; [95% CI: 81%, 88%]) was higher compared to older age groups (<65% for all other age groups). VE estimates did not differ by sex and race/ethnicity. VE against symptomatic infection was the highest for individuals with a prior infection followed by full vaccination. VE against symptomatic infection after the 2-dose mRNA-1273 vaccine (82% [95% CI: 80%, 84%]) was higher compared to the BNT162b2 vaccine (76% [95% CI: 74%, 78%]) in the delta period. VE after 1-dose of the Ad26.COV2.S vaccine was the lowest compared to other vaccines (19% [95% CI: 15%, 23%]) in the delta period. CONCLUSIONS: VE against infection after two doses of the mRNA vaccines was high initially, but significantly reduced against the delta variant for both FDA-approved vaccines.

Severe Acute Respiratory Syndrome Coronavirus 2 Incidence and Risk Factors in a National, Community-Based Prospective Cohort of US Adults.

BACKGROUND: Prospective cohort studies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) incidence complement case-based surveillance and cross-sectional seroprevalence surveys. METHODS: We estimated the incidence of SARS-CoV-2 infection in a national cohort of 6738 US adults, enrolled in March-August 2020. Using Poisson models, we examined the association of social distancing and a composite epidemiologic risk score with seroconversion. The risk score was created using least absolute shrinkage selection operator (LASSO) regression to identify factors predictive of seroconversion. The selected factors were household crowding, confirmed case in household, indoor dining, gathering with groups of ≥10, and no masking in gyms or salons. RESULTS: Among 4510 individuals with ≥1 serologic test, 323 (7.3% [95% confidence interval (CI), 6.5%-8.1%]) seroconverted by January 2021. Among 3422 participants seronegative in May-September 2020 and retested from November 2020 to January 2021, 161 seroconverted over 1646 person-years of follow-up (9.8 per 100 person-years [95% CI, 8.3-11.5]). The seroincidence rate was lower among women compared with men (incidence rate ratio [IRR], 0.69 [95% CI, .50-.94]) and higher among Hispanic (2.09 [1.41-3.05]) than white non-Hispanic participants. In adjusted models, participants who reported social distancing with people they did not know (IRR for always vs never social distancing, 0.42 [95% CI, .20-1.0]) and with people they knew (IRR for always vs never, 0.64 [.39-1.06]; IRR for sometimes vs never, 0.60 [.38-.96]) had lower seroconversion risk. Seroconversion risk increased with epidemiologic risk score (IRR for medium vs low score, 1.68 [95% CI, 1.03-2.81]; IRR for high vs low score, 3.49 [2.26-5.58]). Only 29% of those who seroconverted reported isolating, and only 19% were asked about contacts. CONCLUSIONS: Modifiable risk factors and poor reach of public health strategies drove SARS-CoV-2 transmission across the United States.

The Importance of Incorporating At-Home Testing Into SARS-CoV-2 Point Prevalence Estimates: Findings From a US National Cohort, February 2022.

BACKGROUND: Passive, case-based surveillance underestimates the true extent of active infections in the population due to undiagnosed and untested cases, the exclusion of probable cases diagnosed point-of-care rapid antigen tests, and the exclusive use of at-home rapid tests which are not reported as part of case-based surveillance. The extent in which COVID-19 surveillance may be underestimating the burden of infection is likely due to time-varying factors such as decreased test-seeking behaviors and increased access to and availability of at-home testing. OBJECTIVE: The objective of this study is to estimate the prevalence of SARS-CoV-2 based on different definitions of a case to ascertain the extent to which cases of SARS-CoV-2 may be underestimated by case-based surveillance. METHODS: A survey on COVID-19 exposure, infection, and testing was administered to calculate point prevalence of SARS-CoV-2 among a diverse sample of cohort adults from February 8, 2022, to February 22, 2022. Three-point prevalence estimates were calculated among the cohort, as follows: (1) proportion positives based on polymerase chain reaction (PCR) and rapid antigen tests; (2) proportion positives based on testing exclusively with rapid at-home tests; and (3) proportion of probable undiagnosed cases. Test positivity and prevalence differences across booster status were also examined. RESULTS: Among a cohort of 4328, there were a total of 644 (14.9%) cases. The point prevalence estimate based on PCR or rapid antigen tests was 5.5% (95% CI 4.8%-6.2%), 3.7% (95% CI 3.1%-4.2%) based on at-home rapid tests, and 5.7% (95% CI 5.0%-6.4%) based on the case definition of a probable case. The total point prevalence across all definitions was 14.9% (95% CI 13.8%-16.0%). The percent positivity among PCR or rapid tests was 50.2%. No statistically significant differences were observed in prevalence between participants with a COVID-19 booster compared to fully vaccinated and nonboosted participants except among exclusive at-home rapid testers. CONCLUSIONS: Our findings suggest a substantial number of cases were missed by case-based surveillance systems during the Omicron B.1.1.529 surge, when at-home testing was common. Point prevalence surveys may be a rapid tool to be used to understand SARS-CoV-2 prevalence and would be especially important during case surges to measure the scope and spread of active infections in the population.

Racial/Ethnic Disparities in Exposure, Disease Susceptibility, and Clinical Outcomes during COVID-19 Pandemic in National Cohort of Adults, United States.

We examined racial/ethnic disparities for COVID-19 seroconversion and hospitalization within a prospective cohort (n = 6,740) in the United States enrolled in March 2020 and followed-up through October 2021. Potential SARS-CoV-2 exposure, susceptibility to COVID-19 complications, and access to healthcare varied by race/ethnicity. Hispanic and Black non-Hispanic participants had more exposure risk and difficulty with healthcare access than white participants. Participants with more exposure had greater odds of seroconversion. Participants with more susceptibility and more barriers to healthcare had greater odds of hospitalization. Race/ethnicity positively modified the association between susceptibility and hospitalization. Findings might help to explain the disproportionate burden of SARS-CoV-2 infections and complications among Hispanic/Latino/a and Black non-Hispanic persons. Primary and secondary prevention efforts should address disparities in exposure, vaccination, and treatment for COVID-19.

Presence of SARS-CoV-2 antibodies following COVID-19 diagnosis: a longitudinal study of patients at a major urgent care provider in New York.

The duration of antibody persistence following natural infection is unclear. We examined routine SARS-CoV-2 diagnostic and serological testing data on 6522 persons diagnosed between March 2020 and March 2021 who had at least 1 antibody test ≥30 days after diagnosis at CityMD, an urgent care provider. Using survival analysis, we estimated the median duration of detectable anti-SARS-CoV-2 antibodies and hazard of seroreversion by demographic and clinical characteristics. We found that over 90% (95% CI: 91.8%, 94.8%) of the study population had detectable levels of antibodies at 180 days post diagnosis and that SARS-CoV-2 antibodies persisted at a detectable level for a median duration of 342 days following infection (95% CI: 328, 361). Additionally, there were differences in antibody persistence by age, with older patients less likely to serorevert compared to younger patients. These findings suggest that protection from natural infection may wane with time and differ by demographic factors.

SARS-CoV-2 pandemic in New York metropolitan area: the view from a major urgent care provider.

PURPOSE: Tracking severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing and positivity trends is crucial for understanding the trajectory of the pandemic. We describe demographic and clinical characteristics, testing, and positivity rates for SARS-CoV-2 among 2.8 million patients evaluated at an urgent care provider. METHODS: We conducted a retrospective study of patients receiving a diagnostic or serologic test for SARS-CoV-2 between March 1, 2020 and July 20, 2021 at 115 CityMD locations in the New York metropolitan area. Temporal trends in SARS-CoV-2 positivity by diagnostic and serologic tests stratified by age, sex, race/ethnicity, and borough of residence were assessed. RESULTS: During the study period, 6.1 million COVID diagnostic and serological tests were performed on 2.8 million individuals. Testing levels were higher among 20-29-year-old, non-Hispanic White, and female patients compared with other groups. About 35% were repeat testers. Reverse transcriptase polymerase chain reaction positivity was higher in non-Hispanic Black (7.9%), Hispanic (8.2%), and Native American (8.2%) compared to non-Hispanic White (5.7%) patients. Overall seropositivity was estimated to be 22.1% (95% confidence interval: 22.0-22.2) and was highest among 10-14 year olds (27.9%), and non-Hispanic Black (26.0%) and Hispanic (31.0%) testers. CONCLUSION: Urgent care centers can provide broad access to diagnostic testing and critical evaluation for ambulatory patients during pandemics, especially in population-dense, urban epicenters.  Urgent care center electronic medical records data can provide in-depth surveillance during pandemics complementary to citywide health department data sources.

COVID-19 Testing Among US Children, Parental Preferences for Testing Venues, and Acceptability of School-Based Testing.

OBJECTIVES: Testing remains critical for identifying pediatric cases of COVID-19 and as a public health intervention to contain infections. We surveyed US parents to measure the proportion of children tested for COVID-19 since the start of the pandemic, preferred testing venues for children, and acceptability of school-based COVID-19 testing. METHODS: We conducted an online survey of 2074 US parents of children aged ≤12 years in March 2021. We applied survey weights to generate national estimates, and we used Rao-Scott adjusted Pearson χ2 tests to compare incidence by selected sociodemographic characteristics. We used Poisson regression models with robust SEs to estimate adjusted risk ratios (aRRs) of pediatric testing. RESULTS: Among US parents, 35.9% reported their youngest child had ever been tested for COVID-19. Parents who were female versus male (aRR = 0.69; 95% CI, 0.60-0.79), Asian versus non-Hispanic White (aRR = 0.58; 95% CI, 0.39-0.87), and from the Midwest versus the Northeast (aRR = 0.76; 95% CI, 0.63-0.91) were less likely to report testing of a child. Children who had health insurance versus no health insurance (aRR = 1.38; 95% CI, 1.05-1.81), were attending in-person school/daycare versus not attending (aRR = 1.67; 95% CI, 1.43-1.95), and were from households with annual household income ≥$100 000 versus income <$50 000-$99 999 (aRR = 1.19; 95% CI, 1.02-1.40) were more likely to have tested for COVID-19. Half of parents (52.7%) reported the pediatrician's office as the most preferred testing venue, and 50.6% said they would allow their youngest child to be tested for COVID-19 at school/daycare if required. CONCLUSIONS: Greater efforts are needed to ensure access to COVID-19 testing for US children, including those without health insurance.

Determinants and Trends of COVID-19 Vaccine Hesitancy and Vaccine Uptake in a National Cohort of US Adults: A Longitudinal Study.

We estimated the trends and correlates of vaccine hesitancy and its association with subsequent vaccine uptake among 5,458 adults in the United States. Participants belonged to the Communities, Households, and SARS-CoV-2 Epidemiology COVID (CHASING COVID) Cohort, a national longitudinal study. Trends and correlates of vaccine hesitancy were examined longitudinally in 8 interview rounds from October 2020 to July 2021. We also estimated the association between willingness to vaccinate and subsequent vaccine uptake through July 2021. Vaccine delay and refusal decreased from 51% and 8% in October 2020 to 8% and 6% in July 2021, respectively. Compared with non-Hispanic (NH) White participants, NH Black and Hispanic participants had higher adjusted odds ratios (aOR) for both vaccine delay (for NH Black, aOR = 2.0 (95% confidence interval (CI): 1.5, 2.7), and for Hispanic, 1.3 (95% CI: 1.0, 1.7)) and vaccine refusal (for NH Black, aOR = 2.5 (95% CI: 1.8, 3.6), and for Hispanic, 1.4 (95% CI: 1.0, 2.0)) in June 2021. COVID-19 vaccine hesitancy, compared with vaccine-willingness, was associated with lower odds of subsequent vaccine uptake (for vaccine delayers, aOR = 0.15, 95% CI: 0.13, 0.18; for vaccine refusers, aOR = 0.02; 95% CI: 0.01, 0.03 ), adjusted for sociodemographic factors and COVID-19 history. Vaccination awareness and distribution efforts should focus on vaccine delayers.

Racial/ethnic disparities in exposure to COVID-19, susceptibility to COVID-19 and access to health care - findings from a U.S. national cohort.

We examined the influence of racial/ethnic differences in socioeconomic position on COVID-19 seroconversion and hospitalization within a community-based prospective cohort enrolled in March 2020 and followed through October 2021 (N=6740). The ability to social distance as a measure of exposure to COVID-19, susceptibility to COVID-19 complications, and access to healthcare varied by race/ethnicity with non-white participants having more exposure risk and more difficulty with healthcare access than white participants. Participants with more (versus less) exposure had greater odds of seroconversion (aOR:1.64, 95% Confidence Interval [CI] 1.18-2.29). Participants with more susceptibility and more barriers to healthcare had greater odds of hospitalization (respective aOR:2.36; 1.90-2.96 and 2.31; 1.69-2.68). Race/ethnicity positively modified the association between susceptibility and hospitalization (aORnon-White:2.79, 2.06-3.78). Findings may explain the disproportionate burden of COVID-19 infections and complications among Hispanic and non-Hispanic Black persons. Primary and secondary prevention efforts should address disparities in exposure, COVID-19 vaccination, and treatment.

Patterns of SARS-CoV-2 Testing Preferences in a National Cohort in the United States: Latent Class Analysis of a Discrete Choice Experiment.

BACKGROUND: Inadequate screening and diagnostic testing in the United States throughout the first several months of the COVID-19 pandemic led to undetected cases transmitting disease in the community and an underestimation of cases. Though testing supply has increased, maintaining testing uptake remains a public health priority in the efforts to control community transmission considering the availability of vaccinations and threats from variants. OBJECTIVE: This study aimed to identify patterns of preferences for SARS-CoV-2 screening and diagnostic testing prior to widespread vaccine availability and uptake. METHODS: We conducted a discrete choice experiment (DCE) among participants in the national, prospective CHASING COVID (Communities, Households, and SARS-CoV-2 Epidemiology) Cohort Study from July 30 to September 8, 2020. The DCE elicited preferences for SARS-CoV-2 test type, specimen type, testing venue, and result turnaround time. We used latent class multinomial logit to identify distinct patterns of preferences related to testing as measured by attribute-level part-worth utilities and conducted a simulation based on the utility estimates to predict testing uptake if additional testing scenarios were offered. RESULTS: Of the 5098 invited cohort participants, 4793 (94.0%) completed the DCE. Five distinct patterns of SARS-CoV-2 testing emerged. Noninvasive home testers (n=920, 19.2% of participants) were most influenced by specimen type and favored less invasive specimen collection methods, with saliva being most preferred; this group was the least likely to opt out of testing. Fast-track testers (n=1235, 25.8%) were most influenced by result turnaround time and favored immediate and same-day turnaround time. Among dual testers (n=889, 18.5%), test type was the most important attribute, and preference was given to both antibody and viral tests. Noninvasive dual testers (n=1578, 32.9%) were most strongly influenced by specimen type and test type, preferring saliva and cheek swab specimens and both antibody and viral tests. Among hesitant home testers (n=171, 3.6%), the venue was the most important attribute; notably, this group was the most likely to opt out of testing. In addition to variability in preferences for testing features, heterogeneity was observed in the distribution of certain demographic characteristics (age, race/ethnicity, education, and employment), history of SARS-CoV-2 testing, COVID-19 diagnosis, and concern about the pandemic. Simulation models predicted that testing uptake would increase from 81.6% (with a status quo scenario of polymerase chain reaction by nasal swab in a provider's office and a turnaround time of several days) to 98.1% by offering additional scenarios using less invasive specimens, both viral and antibody tests from a single specimen, faster turnaround time, and at-home testing. CONCLUSIONS: We identified substantial differences in preferences for SARS-CoV-2 testing and found that offering additional testing options would likely increase testing uptake in line with public health goals. Additional studies may be warranted to understand if preferences for testing have changed since the availability and widespread uptake of vaccines.

Durability of protection after 5 doses of acellular pertussis vaccine among 5-9 year old children in King County, Washington.

PURPOSE: Waning of immunity after vaccination with the acellular Pertussis (aP) vaccine has been proposed as one of the main reasons for pertussis resurgence in the US. In this study, we estimated time-varying vaccine effectiveness after 5 doses of aP vaccine. METHODS: We conducted a retrospective cohort study among children 5-9 years old (born between 2008 and 2012) living in King County, Washington, USA, who participated in the Washington State Immunization Information System. We estimated time-varying vaccine effectiveness after 5 doses of aP using smoothed scaled Schoenfeld residuals obtained from fitting Cox proportional hazards models to the data as well as piecewise constant Poisson regression. RESULTS: There were 55 pertussis cases in this cohort, of whom 22 (40%) were fully-vaccinated and 33 (60%) were under-vaccinated. Vaccine effectiveness (VE) remained high for up to 42 months after the fifth dose (VE(t) = 89%; 95% CI: 64%, 97%) as estimated using survival analysis methods and up to 4 years (VE(t) = 93%; 95% CI: 67%, 98%) as estimated using Poisson regression. CONCLUSION: We did not find evidence for waning of vaccine effectiveness for up to four years after 5 doses of aP among 5 -9 years old children in King County, WA.

Association of Diphtheria-Tetanus-Acellular Pertussis Vaccine Timeliness and Number of Doses With Age-Specific Pertussis Risk in Infants and Young Children.

Importance: In most countries, the diphtheria-tetanus-acellular pertussis (DTaP) vaccine is administered as a 3-dose infant series followed by additional booster doses in the first 5 years of life. Short-term immunity from the DTaP vaccine can depend on the number, timing, and interval between doses. Not receiving doses in a timely manner might be associated with a higher pertussis risk. Objective: To examine the association between number and timeliness of vaccine doses and age-specific pertussis risk. Design, Setting, and Participants: This population-based, retrospective cohort study used Washington State Immunization Information System data and pertussis surveillance data from Public Health Seattle and King County, Washington. Included participants were children aged 3 months to 9 years born or living in King County, Washington, between January 1, 2008, and December 31, 2017. Data were analyzed from June 30 to December 1, 2019. Exposures: Being undervaccinated (receiving fewer than recommended doses at a given age) or delayed vaccination (not receiving doses within time frames recommended by Centers for Disease Control and Prevention). Main Outcomes and Measures: Suspected, probable, and confirmed pertussis diagnosis. Results: A total of 316 404 children (median age, 65.2 months [interquartile range, 35.3-94.1 months]; 162 025 boys [51.2%]) as of December 31, 2017, with 17.4 million person-months of follow-up were included in the analysis. A total of 19 943 children (6.3%) had no vaccines recorded in the Immunization Information System, 116 193 (36.7%) received a vaccine with a delay, and 180 268 (56.9%) were fully vaccinated with no delay. Delayed vaccination and undervaccination rates were higher for older children (17.6% delayed or undervaccinated at age 2 months for dose 1 at 3 months vs 41.6% at age 5 years for dose 5) but improved for successive birth cohorts (52.2% for 2008 birth cohort vs 32.3% for 2017 birth cohort). Undervaccination was significantly associated with higher risk of pertussis for the 3-dose primary series (adjusted relative risk [aRR], 4.8; 95% CI, 3.1-7.6), the first booster (aRR, 3.2; 95% CI, 2.3-4.5), and the second booster (aRR, 4.6; 95% CI, 2.6-8.2). However, delay in vaccination among children who received the recommended number of vaccine doses was not associated with pertussis risk. Conclusions and Relevance: The results of this cohort study suggest that undervaccination is associated with higher pertussis risk. Short delays in vaccine receipt may be less important if the age-appropriate number of doses is administered, but delaying doses is not recommended. Ensuring that children receive all doses of pertussis vaccine, even if there is some delay, is important.

The emergence, surge and subsequent wave of the SARS-CoV-2 pandemic in New York metropolitan area: The view from a major region-wide urgent care provider.

BACKGROUND: Describing SARS-CoV-2 testing and positivity trends among urgent care users is crucial for understanding the trajectory of the pandemic. OBJECTIVE: To describe demographic and clinical characteristics, positivity rates, and repeat testing patterns among patients tested for SARS-CoV-2 at CityMD, an urgent care provider in the New York City metropolitan area. DESIGN: Retrospective study of all persons testing for SARS-CoV-2 between March 1, 2020 and January 8, 2021 at 115 CityMD locations in the New York metropolitan area. PATIENTS: Individuals receiving a SARS-CoV-2 diagnostic or serologic test. MEASUREMENTS: Test and individual level SARS-CoV-2 positivity by PCR, rapid antigen, or serologic tests. RESULTS: During the study period, 3.4 million COVID tests were performed on 1.8 million individuals. In New York City, CityMD diagnosed 268,298 individuals, including 17% of all reported cases. Testing levels were higher among 20-29 year olds, non-Hispanic Whites, and females compared with other groups. About 24.8% (n=464,902) were repeat testers. Test positivity was higher in non-Hispanic Black (6.4%), Hispanic (8.0%), and Native American (8.0%) patients compared to non-Hispanic White (5.4%) patients. Overall seropositivity was estimated to be 21.7% (95% Confidence Interval [CI]: 21.6-21.8) and was highest among 10-14 year olds (27.3%). Seropositivity was also high among non-Hispanic Black (24.5%) and Hispanic (30.6%) testers, and residents of the Bronx (31.3%) and Queens (30.5%). Using PCR as the gold standard, SARS-CoV-2 rapid tests had a false positive rate of 5.4% (95%CI 5.3-5.5). CONCLUSION: Urgent care centers can provide broad access to critical evaluation, diagnostic testing and treatment of a substantial number of ambulatory patients during pandemics, especially in population-dense, urban epicenters.

Estimating Population-Level Effects of the Acellular Pertussis Vaccine Using Routinely Collected Immunization Data.

BACKGROUND: Measuring and reporting the different population-level effects of the acellular pertussis vaccine on pertussis disease in addition to direct effects can increase the cost-effectiveness of a vaccine. METHODS: We conducted a retrospective cohort study of children born between 1 January 2008 and 31 December 2017, in King County, Washington, who were enrolled in the Washington State Immunization Information System. Diphtheria, tetanus toxoids, and acellular pertussis (DTaP) vaccination data from in the Washington State Immunization Information System was linked with pertussis case data from Public Health Seattle and King County. Census-level vaccination coverage was estimated as proportion of age-appropriately vaccinated children residing in it. Direct vaccine effectiveness was estimated by comparing pertussis risk in fully vaccinated and undervaccinated children. Population-level vaccine effectiveness (VE) measures were estimated by comparing pertussis risk in census tracts in the highest quartile for vaccination coverage with that in the lowest quartile. RESULTS: For direct protection, estimated VE was 76% (95% confidence interval, 63%-84%) in low-vaccination-coverage clusters, and it decreased to 47% (13%-68%) in high-coverage clusters, after adjustment for potential confounders. The estimated indirect VE was 45.0% (95% confidence interval, 1%-70%), the total VE 93.9% (91%-96%), and the overall VE 42.2% (19%-60%). CONCLUSION: Our findings suggest that DTaP vaccination provided direct as well as indirect protection in the highly immunized King County, Washington. Routine DTaP vaccination programs may have the potential to provide not only protection for vaccinated individuals but also for the undervaccinated individuals living in the same area.