Severe Acute Respiratory Syndrome Coronavirus 2 Infection History and Antibody Response to 3 Coronavirus Disease 2019 Messenger RNA Vaccine Doses.

BACKGROUND: Data on antibody kinetics are limited among individuals previously infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). From a cohort of healthcare personnel and other frontline workers in 6 US states, we assessed antibody waning after messenger RNA (mRNA) dose 2 and response to dose 3 according to SARS-CoV-2 infection history. METHODS: Participants submitted sera every 3 months, after SARS-CoV-2 infection, and after each mRNA vaccine dose. Sera were tested for antibodies and reported as area under the serial dilution curve (AUC). Changes in AUC values over time were compared using a linear mixed model. RESULTS: Analysis included 388 participants who received dose 3 by November 2021. There were 3 comparison groups: vaccine only with no known prior SARS-CoV-2 infection (n = 224); infection prior to dose 1 (n = 123); and infection after dose 2 and before dose 3 (n = 41). The interval from dose 2 and dose 3 was approximately 8 months. After dose 3, antibody levels rose 2.5-fold (95% confidence interval [CI] = 2.2-3.0) in group 2 and 2.9-fold (95% CI = 2.6-3.3) in group 1. Those infected within 90 days before dose 3 (and median 233 days [interquartile range, 213-246] after dose 2) did not increase significantly after dose 3. CONCLUSIONS: A third dose of mRNA vaccine typically elicited a robust humoral immune response among those with primary vaccination regardless of SARS-CoV-2 infection >3 months prior to boosting. Those with infection <3 months prior to boosting did not have a significant increase in antibody concentrations in response to a booster.

Risk Factors for Reinfection with SARS-CoV-2 Omicron Variant among Previously Infected Frontline Workers.

In a cohort of essential workers in the United States previously infected with SARS-CoV-2, risk factors for reinfection included being unvaccinated, infrequent mask use, time since first infection, and being non-Hispanic Black. Protecting workers from reinfection requires a multipronged approach including up-to-date vaccination, mask use as recommended, and reduction in underlying health disparities.

Association of mRNA Vaccination With Clinical and Virologic Features of COVID-19 Among US Essential and Frontline Workers.

Importance: Data on the epidemiology of mild to moderately severe COVID-19 are needed to inform public health guidance. Objective: To evaluate associations between 2 or 3 doses of mRNA COVID-19 vaccine and attenuation of symptoms and viral RNA load across SARS-CoV-2 viral lineages. Design, Setting, and Participants: A prospective cohort study of essential and frontline workers in Arizona, Florida, Minnesota, Oregon, Texas, and Utah with COVID-19 infection confirmed by reverse transcriptase-polymerase chain reaction testing and lineage classified by whole genome sequencing of specimens self-collected weekly and at COVID-19 illness symptom onset. This analysis was conducted among 1199 participants with SARS-CoV-2 from December 14, 2020, to April 19, 2022, with follow-up until May 9, 2022, reported. Exposures: SARS-CoV-2 lineage (origin strain, Delta variant, Omicron variant) and COVID-19 vaccination status. Main Outcomes and Measures: Clinical outcomes included presence of symptoms, specific symptoms (including fever or chills), illness duration, and medical care seeking. Virologic outcomes included viral load by quantitative reverse transcriptase-polymerase chain reaction testing along with viral viability. Results: Among 1199 participants with COVID-19 infection (714 [59.5%] women; median age, 41 years), 14.0% were infected with the origin strain, 24.0% with the Delta variant, and 62.0% with the Omicron variant. Participants vaccinated with the second vaccine dose 14 to 149 days before Delta infection were significantly less likely to be symptomatic compared with unvaccinated participants (21/27 [77.8%] vs 74/77 [96.1%]; OR, 0.13 [95% CI, 0-0.6]) and, when symptomatic, those vaccinated with the third dose 7 to 149 days before infection were significantly less likely to report fever or chills (5/13 [38.5%] vs 62/73 [84.9%]; OR, 0.07 [95% CI, 0.0-0.3]) and reported significantly fewer days of symptoms (10.2 vs 16.4; difference, -6.1 [95% CI, -11.8 to -0.4] days). Among those with Omicron infection, the risk of symptomatic infection did not differ significantly for the 2-dose vaccination status vs unvaccinated status and was significantly higher for the 3-dose recipients vs those who were unvaccinated (327/370 [88.4%] vs 85/107 [79.4%]; OR, 2.0 [95% CI, 1.1-3.5]). Among symptomatic Omicron infections, those vaccinated with the third dose 7 to 149 days before infection compared with those who were unvaccinated were significantly less likely to report fever or chills (160/311 [51.5%] vs 64/81 [79.0%]; OR, 0.25 [95% CI, 0.1-0.5]) or seek medical care (45/308 [14.6%] vs 20/81 [24.7%]; OR, 0.45 [95% CI, 0.2-0.9]). Participants with Delta and Omicron infections who received the second dose 14 to 149 days before infection had a significantly lower mean viral load compared with unvaccinated participants (3 vs 4.1 log10 copies/µL; difference, -1.0 [95% CI, -1.7 to -0.2] for Delta and 2.8 vs 3.5 log10 copies/µL, difference, -1.0 [95% CI, -1.7 to -0.3] for Omicron). Conclusions and Relevance: In a cohort of US essential and frontline workers with SARS-CoV-2 infections, recent vaccination with 2 or 3 mRNA vaccine doses less than 150 days before infection with Delta or Omicron variants, compared with being unvaccinated, was associated with attenuated symptoms, duration of illness, medical care seeking, or viral load for some comparisons, although the precision and statistical significance of specific estimates varied.

In Search of a Value Proposition for COVID-19 Testing in the Work Environment: A Social Marketing Analysis.

BACKGROUND: This study examined employer experience with SARS-CoV-2 (COVID-19) asymptomatic testing through a social marketing lens. Social marketing uses commercial marketing principles to achieve socially beneficial ends including improved health and safety behavior. METHOD: Twenty employers across 11 occupational sectors were interviewed about implementation of COVID-19 testing from January through April 2021. Recorded transcripts were coded and analyzed using marketing's "Four P's": "product," "price," "place," "promotion." RESULTS: COVID-19 tests (product) were uncomfortable, were easily confused, and didn't solve problems articulated by employers. Testing was not widely available or didn't line up with shifts or locations (place). The perceived price, which included direct and associated costs (e.g., laboratory fees, productivity loss, logistical challenges) was high. Most crucially, the time to receive (PCR) results negated the major benefit of less time spent in quarantine and challenged employer trust. A potential audience segmentation strategy based on perceptions of exposure risk also emerged. CONCLUSIONS: This social marketing analysis suggests ways to improve the value proposition for asymptomatic testing through changes in product, price, and placement features in line with employers' expressed needs. Study findings can also inform creation of employee communication materials that balance perceived rewards of testing against perceived risks of exposure.

Barriers to SARS-CoV-2 Testing among U.S. Employers in the COVID-19 Pandemic: A Qualitative Analysis Conducted January through April 2021.

During the first year of the COVID-19 pandemic, U.S. companies were seeking ways to support their employees to return to the workplace. Nonetheless, the development of strategies to support the access, use, and interpretation of SARS-CoV-2 testing was challenging. In the present study, we explore, from the perspective of owners and company leadership, the barriers to SARS-CoV-2 testing among U.S. companies. Key informant interviews with company representatives were conducted during January-April 2021 about SARS-CoV-2 testing. A pre-interview survey assessed respondent socio-demographic and organizational characteristics. Interview sessions were transcribed, coded, and analyzed using MaxQDA. A total of twenty interviews were completed with at least two interviews conducted in each major U.S. industry sector. Ninety percent of participants represented companies in business >10 years, comprising both small and large workforces. Using a grounded theory approach, six themes emerged: (1) access to and knowledge of SARS-CoV-2 tests; (2) strategies for symptomatic and asymptomatic testing of workers; (3) type/availability of personal protective equipment to mitigate coronavirus exposures; (4) return-to-work policies; (5) guidance and communication of SARS-CoV-2 Testing; and (6) use of contact tracing and SARS-CoV-2 vaccination. Various modifiable and non-modifiable challenges for SARS-CoV-2 testing among U.S. companies were identified and can inform work-related SARS-CoV-2 testing strategies.

Detection and Stability of SARS-CoV-2 in Three Self-Collected Specimen Types: Flocked Midturbinate Swab (MTS) in Viral Transport Media, Foam MTS, and Saliva.

Respiratory specimen collection materials shortages hampers severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing. We compared specimen alternatives and evaluated SARS-CoV-2 RNA stability under simulated shipping conditions. We compared concordance of RT-PCR detection of SARS-CoV-2 from flocked midturbinate swabs (MTS) in viral transport media (VTM), foam MTS without VTM, and saliva. Specimens were collected between August 2020 and April 2021 from three prospective cohorts. We compared RT-PCR cycle quantification (Cq) for Spike (S), Nucleocapsid (N), and the Open Reading Frame 1ab (ORF) genes for flocked MTS and saliva specimens tested before and after exposure to a range of storage temperatures (4-30°C) and times (2, 3, and 7 days). Of 1,900 illnesses with ≥2 specimen types tested, 335 (18%) had SARS-CoV-2 detected in ≥1 specimen; 304 (91%) were concordant across specimen types. Among illnesses with SARS-CoV-2 detection, 97% (95% confidence interval [CI]: 94-98%) were positive on flocked MTS, 99% (95% CI: 97-100%) on saliva, and 89% (95% CI: 84-93%) on foam MTS. SARS-CoV-2 RNA was detected in flocked MTS and saliva stored up to 30°C for 7 days. All specimen types provided highly concordant SARS-CoV-2 results. These findings support a range of viable options for specimen types, collection, and transport methods that may facilitate SARS-CoV-2 testing during supply and personnel shortages. IMPORTANCE Findings from this analysis indicate that (1) self-collection of flocked and foam MTS and saliva samples is feasible in both adults and children, (2) foam MTS with VTM and saliva are both viable and reasonable alternatives to traditional flocked MTS in VTM for SARS-CoV-2 detection, and (3) these sample types may be stored and transported at ambient temperatures for up to 7 days without compromising sample quality. These findings support methods of sample collection for SARS-CoV-2 detection that may facilitate widespread community testing in the setting of supply and personnel shortages during the current pandemic.

Pediatric Research Observing Trends and Exposures in COVID-19 Timelines (PROTECT): Protocol for a Multisite Longitudinal Cohort Study.

BACKGROUND: Assessing the real-world effectiveness of COVID-19 vaccines and understanding the incidence and severity of SARS-CoV-2 illness in children are essential to inform policy and guide health care professionals in advising parents and caregivers of children who test positive for SARS-CoV-2. OBJECTIVE: This report describes the objectives and methods for conducting the Pediatric Research Observing Trends and Exposures in COVID-19 Timelines (PROTECT) study. PROTECT is a longitudinal prospective pediatric cohort study designed to estimate SARS-CoV-2 incidence and COVID-19 vaccine effectiveness (VE) against infection among children aged 6 months to 17 years, as well as differences in SARS-CoV-2 infection and vaccine response between children and adolescents. METHODS: The PROTECT multisite network was initiated in July 2021, which aims to enroll approximately 2305 children across four US locations and collect data over a 2-year surveillance period. The enrollment target was based on prospective power calculations and accounts for expected attrition and nonresponse. Study sites recruit parents and legal guardians of age-eligible children participating in the existing Arizona Healthcare, Emergency Response, and Other Essential Workers Surveillance (HEROES)-Research on the Epidemiology of SARS-CoV-2 in Essential Response Personnel (RECOVER) network as well as from surrounding communities. Child demographics, medical history, COVID-19 exposure, vaccination history, and parents/legal guardians' knowledge and attitudes about COVID-19 are collected at baseline and throughout the study. Mid-turbinate nasal specimens are self-collected or collected by parents/legal guardians weekly, regardless of symptoms, for SARS-CoV-2 and influenza testing via reverse transcription-polymerase chain reaction (RT-PCR) assay, and the presence of COVID-like illness (CLI) is reported. Children who test positive for SARS-CoV-2 or influenza, or report CLI are monitored weekly by online surveys to report exposure and medical utilization until no longer ill. Children, with permission of their parents/legal guardians, may elect to contribute blood at enrollment, following SARS-CoV-2 infection, following COVID-19 vaccination, and at the end of the study period. PROTECT uses electronic medical record (EMR) linkages where available, and verifies COVID-19 and influenza vaccinations through EMR or state vaccine registries. RESULTS: Data collection began in July 2021 and is expected to continue through the spring of 2023. As of April 13, 2022, 2371 children are enrolled in PROTECT. Enrollment is ongoing at all study sites. CONCLUSIONS: As COVID-19 vaccine products are authorized for use in pediatric populations, PROTECT study data will provide real-world estimates of VE in preventing infection. In addition, this prospective cohort provides a unique opportunity to further understand SARS-CoV-2 incidence, clinical course, and key knowledge gaps that may inform public health. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR1-10.2196/37929.

Effectiveness of 2-Dose BNT162b2 (Pfizer BioNTech) mRNA Vaccine in Preventing SARS-CoV-2 Infection Among Children Aged 5-11 Years and Adolescents Aged 12-15 Years - PROTECT Cohort, July 2021-February 2022.

The BNT162b2 (Pfizer-BioNTech) mRNA COVID-19 vaccine was recommended by CDC's Advisory Committee on Immunization Practices for persons aged 12-15 years (referred to as adolescents in this report) on May 12, 2021, and for children aged 5-11 years on November 2, 2021 (1-4). Real-world data on vaccine effectiveness (VE) in these age groups are needed, especially because when the B.1.1.529 (Omicron) variant became predominant in the United States in December 2021, early investigations of VE demonstrated a decline in protection against symptomatic infection for adolescents aged 12-15 years and adults* (5). The PROTECT† prospective cohort of 1,364 children and adolescents aged 5-15 years was tested weekly for SARS-CoV-2, irrespective of symptoms, and upon COVID-19-associated illness during July 25, 2021-February 12, 2022. Among unvaccinated participants (i.e., those who had received no COVID-19 vaccine doses) with any laboratory-confirmed SARS-CoV-2 infection, those with B.1.617.2 (Delta) variant infections were more likely to report COVID-19 symptoms (66%) than were those with Omicron infections (49%). Among fully vaccinated children aged 5-11 years, VE against any symptomatic and asymptomatic Omicron infection 14-82 days (the longest interval after dose 2 in this age group) after receipt of dose 2 of the Pfizer-BioNTech vaccine was 31% (95% CI = 9%-48%), adjusted for sociodemographic characteristics, health information, frequency of social contact, mask use, location, and local virus circulation. Among adolescents aged 12-15 years, adjusted VE 14-149 days after dose 2 was 87% (95% CI = 49%-97%) against symptomatic and asymptomatic Delta infection and 59% (95% CI = 22%-79%) against Omicron infection. Fully vaccinated participants with Omicron infection spent an average of one half day less sick in bed than did unvaccinated participants with Omicron infection. All eligible children and adolescents should remain up to date with recommended COVID-19 vaccinations.

Neutralizing Antibody Response to Pseudotype Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Differs Between mRNA-1273 and BNT162b2 Coronavirus Disease 2019 (COVID-19) Vaccines and by History of SARS-CoV-2 Infection.

BACKGROUND: Data on the development of neutralizing antibodies (nAbs) against SARS-CoV-2 after SARS-CoV-2 infection and after vaccination with mRNA COVID-19 vaccines are limited. METHODS: From a prospective cohort of 3975 adult essential and frontline workers tested weekly from August 2020 to March 2021 for SARS-CoV-2 infection by reverse transcription-polymerase chain reaction assay irrespective of symptoms, 497 participants had sera drawn after infection (170), vaccination (327), and after both infection and vaccination (50 from the infection population). Serum was collected after infection and each vaccine dose. Serum-neutralizing antibody titers against USA-WA1/2020-spike pseudotype virus were determined by the 50% inhibitory dilution. Geometric mean titers (GMTs) and corresponding fold increases were calculated using t tests and linear mixed-effects models. RESULTS: Among 170 unvaccinated participants with SARS-CoV-2 infection, 158 (93%) developed nAbs with a GMT of 1003 (95% confidence interval, 766-1315). Among 139 previously uninfected participants, 138 (99%) developed nAbs after mRNA vaccine dose 2 with a GMT of 3257 (2596-4052). GMT was higher among those receiving mRNA-1273 vaccine (GMT, 4698; 3186-6926) compared with BNT162b2 vaccine (GMT, 2309; 1825-2919). Among 32 participants with prior SARS-CoV-2 infection, GMT was 21 655 (14 766-31 756) after mRNA vaccine dose 1, without further increase after dose 2. CONCLUSIONS: A single dose of mRNA vaccine after SARS-CoV-2 infection resulted in the highest observed nAb response. Two doses of mRNA vaccine in previously uninfected participants resulted in higher nAbs to SARS-CoV-2 than after 1 dose of vaccine or SARS-CoV-2 infection alone. nAb response also differed by mRNA vaccine product.

Incidence of SARS-CoV-2 infection among COVID-19 vaccinated and unvaccinated healthcare personnel, first responders, and other essential and frontline workers: Eight US locations, January-September 2021.

BACKGROUND: We sought to evaluate the impact of changes in estimates of COVID-19 vaccine effectiveness on the incidence of laboratory-confirmed infection among frontline workers at high risk for SARS-CoV-2. METHODS: We analyzed data from a prospective frontline worker cohort to estimate the incidence of COVID-19 by month as well as the association of COVID-19 vaccination, occupation, demographics, physical distancing, and mask use with infection risk. Participants completed baseline and quarterly surveys, and each week self-collected mid-turbinate nasal swabs and reported symptoms. RESULTS: Among 1018 unvaccinated and 3531 fully vaccinated workers, the monthly incidence of laboratory-confirmed SARS-CoV-2 infection in January 2021 was 13.9 (95% confidence interval [CI]: 10.4-17.4), declining to 0.5 (95% CI -0.4-1.4) per 1000 person-weeks in June. By September 2021, when the Delta variant predominated, incidence had once again risen to 13.6 (95% CI 7.8-19.4) per 1000 person-weeks. In contrast, there was no reportable incidence among fully vaccinated participants at the end of January 2021, and incidence remained low until September 2021 when it rose modestly to 4.1 (95% CI 1.9-3.8) per 1000. Below average facemask use was associated with a higher risk of infection for unvaccinated participants during exposure to persons who may have COVID-19 and vaccinated participants during hours in the community. CONCLUSIONS: COVID-19 vaccination was significantly associated with a lower risk of SARS-CoV-2 infection despite Delta variant predominance. Our data demonstrate the added protective benefit of facemask use among both unvaccinated and vaccinated frontline workers.

Interim Estimate of Vaccine Effectiveness of BNT162b2 (Pfizer-BioNTech) Vaccine in Preventing SARS-CoV-2 Infection Among Adolescents Aged 12-17 Years - Arizona, July-December 2021.

The BNT162b2 (Pfizer-BioNTech) mRNA COVID-19 vaccine has demonstrated high efficacy in preventing infection with SARS-CoV-2 (the virus that causes COVID-19) in randomized placebo-controlled Phase III trials in persons aged 12-17 years (referred to as adolescents in this report) (1); however, data on real-word vaccine effectiveness (VE) among adolescents are limited (1-3). As of December 2021, the Pfizer-BioNTech vaccine is approved by the Food and Drug Administration (FDA) for adolescents aged 16-17 years and under FDA emergency use authorization for those aged 12-15 years. In a prospective cohort in Arizona, 243 adolescents aged 12-17 years were tested for SARS-CoV-2 by reverse transcription-polymerase chain reaction (RT-PCR) each week, irrespective of symptoms, and upon onset of COVID-19-like illness during July 25-December 4, 2021; the SARS-CoV-2 B.1.617.2 (Delta) variant was the predominant strain during this study period. During the study, 190 adolescents contributed fully vaccinated person-time (≥14 days after receiving 2 doses of Pfizer-BioNTech vaccine), 30 contributed partially vaccinated person-time (receipt of 1 dose or receipt of 2 doses but with the second dose completed <14 days earlier), and 66 contributed unvaccinated person-time. Using the Cox proportional-hazards model, the estimated VE of full Pfizer-BioNTech vaccination for preventing SARS-CoV-2 infection was 92% (95% CI = 79%-97%), adjusted for sociodemographic characteristics, health information, frequency of social contact, mask use, location, and local virus circulation. These findings from a real-world setting indicate that 2 doses of Pfizer-BioNTech vaccine are highly effective in preventing SARS-CoV-2 infection among Arizona adolescents. CDC recommends COVID-19 vaccination for all eligible persons in the United States, including persons aged 12-17 years.

Research on the Epidemiology of SARS-CoV-2 in Essential Response Personnel (RECOVER): Protocol for a Multisite Longitudinal Cohort Study.

BACKGROUND: Workers critical to emergency response and continuity of essential services during the COVID-19 pandemic are at a disproportionally high risk of SARS-CoV-2 infection. Prospective cohort studies are needed for enhancing the understanding of the incidence of symptomatic and asymptomatic SARS-CoV-2 infections, identifying risk factors, assessing clinical outcomes, and determining the effectiveness of vaccination. OBJECTIVE: The Research on the Epidemiology of SARS-CoV-2 in Essential Response Personnel (RECOVER) prospective cohort study was designed to estimate the incidence of symptomatic and asymptomatic SARS-CoV-2 infections, examine the risk factors for infection and clinical spectrum of illness, and assess the effectiveness of vaccination among essential workers. METHODS: The RECOVER multisite network was initiated in August 2020 and aims to enroll 3000 health care personnel (HCP), first responders, and other essential and frontline workers (EFWs) at 6 US locations. Data on participant demographics, medical history, and vaccination history are collected at baseline and throughout the study. Active surveillance for the symptoms of COVID-19-like illness (CLI), access of medical care, and symptom duration is performed by text messages, emails, and direct participant or medical record reports. Participants self-collect a mid-turbinate nasal swab weekly, regardless of symptoms, and 2 additional respiratory specimens at the onset of CLI. Blood is collected upon enrollment, every 3 months, approximately 28 days after a reverse transcription polymerase chain reaction (RT-PCR)-confirmed SARS-CoV-2 infection, and 14 to 28 days after a dose of any COVID-19 vaccine. From February 2021, household members of RT-PCR-confirmed participants are self-collecting mid-turbinate nasal swabs daily for 10 days. RESULTS: The study observation period began in August 2020 and is expected to continue through spring 2022. There are 2623 actively enrolled RECOVER participants, including 280 participants who have been found to be positive for SARS-CoV-2 by RT-PCR. Enrollment is ongoing at 3 of the 6 study sites. CONCLUSIONS: Data collected through the cohort are expected to provide important public health information for essential workers at high risk for occupational exposure to SARS-CoV-2 and allow early evaluation of COVID-19 vaccine effectiveness. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/31574.

Prevention and Attenuation of Covid-19 with the BNT162b2 and mRNA-1273 Vaccines.

BACKGROUND: Information is limited regarding the effectiveness of the two-dose messenger RNA (mRNA) vaccines BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) in preventing infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and in attenuating coronavirus disease 2019 (Covid-19) when administered in real-world conditions. METHODS: We conducted a prospective cohort study involving 3975 health care personnel, first responders, and other essential and frontline workers. From December 14, 2020, to April 10, 2021, the participants completed weekly SARS-CoV-2 testing by providing mid-turbinate nasal swabs for qualitative and quantitative reverse-transcriptase-polymerase-chain-reaction (RT-PCR) analysis. The formula for calculating vaccine effectiveness was 100% × (1 - hazard ratio for SARS-CoV-2 infection in vaccinated vs. unvaccinated participants), with adjustments for the propensity to be vaccinated, study site, occupation, and local viral circulation. RESULTS: SARS-CoV-2 was detected in 204 participants (5%), of whom 5 were fully vaccinated (≥14 days after dose 2), 11 partially vaccinated (≥14 days after dose 1 and <14 days after dose 2), and 156 unvaccinated; the 32 participants with indeterminate vaccination status (<14 days after dose 1) were excluded. Adjusted vaccine effectiveness was 91% (95% confidence interval [CI], 76 to 97) with full vaccination and 81% (95% CI, 64 to 90) with partial vaccination. Among participants with SARS-CoV-2 infection, the mean viral RNA load was 40% lower (95% CI, 16 to 57) in partially or fully vaccinated participants than in unvaccinated participants. In addition, the risk of febrile symptoms was 58% lower (relative risk, 0.42; 95% CI, 0.18 to 0.98) and the duration of illness was shorter, with 2.3 fewer days spent sick in bed (95% CI, 0.8 to 3.7). CONCLUSIONS: Authorized mRNA vaccines were highly effective among working-age adults in preventing SARS-CoV-2 infection when administered in real-world conditions, and the vaccines attenuated the viral RNA load, risk of febrile symptoms, and duration of illness among those who had breakthrough infection despite vaccination. (Funded by the National Center for Immunization and Respiratory Diseases and the Centers for Disease Control and Prevention.).

Interim Estimates of Vaccine Effectiveness of BNT162b2 and mRNA-1273 COVID-19 Vaccines in Preventing SARS-CoV-2 Infection Among Health Care Personnel, First Responders, and Other Essential and Frontline Workers - Eight U.S. Locations, December 2020-March 2021.

Messenger RNA (mRNA) BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) COVID-19 vaccines have been shown to be effective in preventing symptomatic COVID-19 in randomized placebo-controlled Phase III trials (1,2); however, the benefits of these vaccines for preventing asymptomatic and symptomatic SARS-CoV-2 (the virus that causes COVID-19) infection, particularly when administered in real-world conditions, is less well understood. Using prospective cohorts of health care personnel, first responders, and other essential and frontline workers* in eight U.S. locations during December 14, 2020-March 13, 2021, CDC routinely tested for SARS-CoV-2 infections every week regardless of symptom status and at the onset of symptoms consistent with COVID-19-associated illness. Among 3,950 participants with no previous laboratory documentation of SARS-CoV-2 infection, 2,479 (62.8%) received both recommended mRNA doses and 477 (12.1%) received only one dose of mRNA vaccine.† Among unvaccinated participants, 1.38 SARS-CoV-2 infections were confirmed by reverse transcription-polymerase chain reaction (RT-PCR) per 1,000 person-days.§ In contrast, among fully immunized (≥14 days after second dose) persons, 0.04 infections per 1,000 person-days were reported, and among partially immunized (≥14 days after first dose and before second dose) persons, 0.19 infections per 1,000 person-days were reported. Estimated mRNA vaccine effectiveness for prevention of infection, adjusted for study site, was 90% for full immunization and 80% for partial immunization. These findings indicate that authorized mRNA COVID-19 vaccines are effective for preventing SARS-CoV-2 infection, regardless of symptom status, among working-age adults in real-world conditions. COVID-19 vaccination is recommended for all eligible persons.

Epidemiology of SARS-CoV-2 antibodies among firefighters/paramedics of a US fire department: a cross-sectional study.

OBJECTIVES: We estimate the point seroprevalence of SARS-CoV-2 antibodies in the frontline firefighter/paramedic workforce of a South Florida fire department located in the epicentre of a State outbreak. METHODS: A cross-sectional study design was used to estimate the point seroprevalence of SARS-CoV-2 antibodies using a rapid immunoglobulin (Ig)M-IgG combined point-of-care lateral flow immunoassay among frontline firefighters/paramedics collected over a 2-day period, 16-17 April 2020. Fire department personnel were emailed a survey link assessing COVID-19 symptoms and work exposures the day prior to the scheduled drive-through antibody testing at a designated fire station. Off-duty and on-duty firefighter/paramedic personnel drove through the fire station/training facility in their personal vehicles or on-duty engine/rescue trucks for SARS-CoV-2 antibody testing. RESULTS: Among the 203 firefighters/paramedics that make up the fire department workforce, 18 firefighters/paramedics (8.9%) tested positive for SARS-CoV-2 antibodies, of which 8 firefighters/paramedics (3.9%) were IgG positive only, 8 (3.9%) were IgM positive only and 2 (0.1%) were IgG/IgM positive. The positive predictive value (PPV) of the serological test is estimated to be 33.2% and the negative predictive value is 99.3%. The average number of COVID-19 case contacts (ie, within 6 feet of an infected person (laboratory-confirmed or probable COVID-19 patient) for ≥15 min) experienced by firefighters/paramedics was higher for those with positive serology compared with those with negative (13.3 cases vs 7.31 cases; p=0.022). None of the antibody positive firefighters/paramedics reported receipt of the annual influenza vaccine compared with firefighters/paramedics who tested negative for SARS-CoV-2 antibodies (0.0% vs 21.0%; p=0.027). CONCLUSION: Rapid SARS-CoV-2 IgM-IgG antibody testing documented early-stage and late-stage infection in a firefighter workforce providing insight to a broader medical surveillance project on return to work for firefighters/paramedics. Given the relatively low PPV of the serological test used in this study back in April 2020, caution should be used in interpreting test results.