Surveillance for Multisystem Inflammatory Syndrome in US Children Aged 5-11 Years Who Received Pfizer-BioNTech COVID-19 Vaccine, November 2021 through March 2022.

Multisystem inflammatory syndrome in children (MIS-C) is a complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; in the United States, reporting of MIS-C after coronavirus disease 2019 (COVID-19) vaccination is required for vaccine safety monitoring. Pfizer-BioNTech COVID-19 vaccine was authorized for children aged 5-11 years on 29 October 2021. Covering a period when approximately 7 million children received vaccine, surveillance for MIS-C ≤ 90 days postvaccination using passive systems identified 58 children with MIS-C and laboratory evidence of past/recent SARS-CoV-2 infection, and 4 without evidence. During a period with extensive SARS-CoV-2 circulation, MIS-C illness in children after COVID-19 vaccination who lacked evidence of SARS-CoV-2 infection was rare (<1 per million vaccinated children).

SARS-CoV-2 Serology and Self-Reported Infection Among Adults - National Health and Nutrition Examination Survey, United States, August 2021-May 2022.

CDC COVID-19 surveillance systems monitor SARS-CoV-2 antibody prevalence to collect information about asymptomatic, undiagnosed, and unreported disease using national convenience samples of blood donor data from commercial laboratories (1,2). However, nonrandom sampling of data from these systems could affect prevalence estimates (1-3). The National Health and Nutrition Examination Survey (NHANES) collects SARS-CoV-2 serology data among a sample of the general U.S. civilian population (4). In addition, NHANES collects self-reported COVID-19 vaccination and disease history, and its statistical sampling design is not based on health care access or blood donation. Therefore, NHANES data can be used to better quantify asymptomatic SARS-CoV-2 infection prevalence and seropositivity attained through infection without vaccination. Preliminary NHANES 2021-2022 results indicated that 41.6% of adults aged ≥18 years had serology indicative of past infection and that 43.7% of these adults, including 57.1% of non-Hispanic Black or African American (Black) adults, reported never having had COVID-19, possibly representing asymptomatic infection. In addition, 25.5% of adults whose serology indicated past infection reported never having received COVID-19 vaccination. Prevalences of seropositivity in the absence of vaccination were higher among younger adults and Black adults, reflecting the lower observed vaccination rates among these groups (5). These findings raise health equity concerns given the disparities observed in SARS-CoV-2 infection and COVID-19 vaccination. Results from NHANES 2021-2022 can guide ongoing efforts to achieve vaccine equity in COVID-19 primary vaccination series and booster dose coverage.

Reinfection With Severe Acute Respiratory Syndrome Coronavirus 2 Among Previously Infected Healthcare Personnel and First Responders.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus testing among first responders and healthcare personnel who participated in a May 2020-August 2020 serosurvey that assessed spike protein antibodies provided an opportunity to assess reinfection. METHODS: Serology survey data were merged with virus testing results from Rhode Island (1 March 2020-17 February 2021) and New York City (10 March 2020-14 December 2020). Participants with a positive virus test ≥14 days before their serology test were included. Reinfection was defined as a second positive SARS-CoV-2 test ≥90 days after the first positive test. The association between serostatus and reinfection was assessed with a proportional hazards model. RESULTS: Among 1572 previously infected persons, 40 (2.5%) were reinfected. Reinfection differed by serostatus: 8.4% among seronegative vs 1.9% among seropositive participants (P < .0001). Most reinfections occurred among Rhode Island nursing home and corrections personnel (n = 30) who were most frequently tested (mean 30.3 tests vs 4.6 for other Rhode Island and 2.3 for New York City participants). The adjusted hazard ratio (aHR) for reinfection in seropositive vs seronegative persons was 0.41 (95% confidence interval [CI], .20-.81). Exposure to a household member with coronavirus disease 2019 (COVID-19) before the serosurvey was also protective (aHR, 0.34; 95% CI, .13-.89). CONCLUSIONS: Reinfections were uncommon among previously infected persons over a 9-month period that preceded widespread variant circulation. Seropositivity decreased reinfection risk. Lower reinfection risk associated with exposure to a household member with COVID-19 may reflect subsequently reduced household transmission.

Duration of Viral Nucleic Acid Shedding and Early Reinfection With Severe Respiratory Syndrome Coronavirus 2 in Healthcare Workers and First Responders.

We estimated the distributions of duration of SARS-CoV-2 nucleic acid shedding and time to reinfection among 137 persons with at least 2 positive nucleic acid amplification test (NAAT) results from March to September 2020. We analyzed gaps of varying length between subsequent positive and negative NAAT results and estimated a mean duration of nucleic acid shedding of 30.1 days (95% confidence interval [CI], 26.3-34.5). Mean time to reinfection was 89.1 days (95% CI, 75.3-103.5). Together, these indicate that a 90-day period between positive NAAT results can reliably define reinfection in immunocompetent persons although reinfection can occur at shorter intervals.

Lack of Antibodies to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in a Large Cohort of Previously Infected Persons.

BACKGROUND: Reports suggest that some persons previously infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lack detectable immunoglobulin G (IgG) antibodies. We aimed to determine the proportion IgG seronegative and predictors for seronegativity among persons previously infected with SARS-CoV-2. METHODS: We analyzed serologic data collected from healthcare workers and first responders in New York City and the Detroit metropolitan area with a history of a positive SARS-CoV-2 reverse-transcription polymerase chain reaction (RT-PCR) test result and who were tested for IgG antibodies to SARS-CoV-2 spike protein at least 2 weeks after symptom onset. RESULTS: Of 2547 persons with previously confirmed SARS-CoV-2 infection, 160 (6.3%) were seronegative. Of 2112 previously symptomatic persons, the proportion seronegative slightly increased from 14 to 90 days post symptom onset (P = .06). The proportion seronegative ranged from 0% among 79 persons previously hospitalized to 11.0% among 308 persons with asymptomatic infections. In a multivariable model, persons who took immunosuppressive medications were more likely to be seronegative (31.9%; 95% confidence interval [CI], 10.7%-64.7%), while participants of non-Hispanic Black race/ethnicity (vs non-Hispanic White; 2.7%; 95% CI, 1.5%-4.8%), with severe obesity (vs under/normal weight; 3.9%; 95% CI, 1.7%-8.6%), or with more symptoms were less likely to be seronegative. CONCLUSIONS: In our population with previous RT-PCR-confirmed infection, approximately 1 in 16 persons lacked IgG antibodies. Absence of antibodies varied independently by illness severity, race/ethnicity, obesity, and immunosuppressive drug therapy. The proportion seronegative remained relatively stable among persons tested up to 90 days post symptom onset.

Coronavirus Disease 2019 Symptoms and Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Positivity in a Large Survey of First Responders and Healthcare Personnel, May-July 2020.

A severe acute respiratory syndrome coronavirus 2 serosurvey among first responder/healthcare personnel showed that loss of taste/smell was most predictive of seropositivity; percent seropositivity increased with number of coronavirus disease 2019 symptoms. However, 22.9% with 9 symptoms were seronegative, and 8.3% with no symptoms were seropositive. These findings demonstrate limitations of symptom-based surveillance and importance of testing.

Severe Acute Respiratory Syndrome Coronavirus 2 Seropositivity among Healthcare Personnel in Hospitals and Nursing Homes, Rhode Island, USA, July-August 2020.

Healthcare personnel are recognized to be at higher risk for infection with severe acute respiratory syndrome coronavirus 2. We conducted a serologic survey in 15 hospitals and 56 nursing homes across Rhode Island, USA, during July 17-August 28, 2020. Overall seropositivity among 9,863 healthcare personnel was 4.6% (95% CI 4.2%-5.0%) but varied 4-fold between hospital personnel (3.1%, 95% CI 2.7%-3.5%) and nursing home personnel (13.1%, 95% CI 11.5%-14.9%). Within nursing homes, prevalence was highest among personnel working in coronavirus disease units (24.1%; 95% CI 20.6%-27.8%). Adjusted analysis showed that in hospitals, nurses and receptionists/medical assistants had a higher likelihood of seropositivity than physicians. In nursing homes, nursing assistants and social workers/case managers had higher likelihoods of seropositivity than occupational/physical/speech therapists. Nursing home personnel in all occupations had elevated seropositivity compared with hospital counterparts. Additional mitigation strategies are needed to protect nursing home personnel from infection, regardless of occupation.

Prevalence of SARS-CoV-2 Antibodies in First Responders and Public Safety Personnel, New York City, New York, USA, May-July 2020.

We conducted a serologic survey in public service agencies in New York City, New York, USA, during May-July 2020 to determine prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among first responders. Of 22,647 participants, 22.5% tested positive for SARS-CoV-2-specific antibodies. Seroprevalence for police and firefighters was similar to overall seroprevalence; seroprevalence was highest in correctional staff (39.2%) and emergency medical technicians (38.3%) and lowest in laboratory technicians (10.1%) and medicolegal death investigators (10.8%). Adjusted analyses demonstrated association between seropositivity and exposure to SARS-CoV-2-positive household members (adjusted odds ratio [aOR] 3.52 [95% CI 3.19-3.87]), non-Hispanic Black race or ethnicity (aOR 1.50 [95% CI 1.33-1.68]), and severe obesity (aOR 1.31 [95% CI 1.05-1.65]). Consistent glove use (aOR 1.19 [95% CI 1.06-1.33]) increased likelihood of seropositivity; use of other personal protective equipment had no association. Infection control measures, including vaccination, should be prioritized for frontline workers.

SARS-CoV-2 Seroprevalence among Healthcare, First Response, and Public Safety Personnel, Detroit Metropolitan Area, Michigan, USA, May-June 2020.

To estimate seroprevalence of severe acute respiratory syndrome 2 (SARS-CoV-2) among healthcare, first response, and public safety personnel, antibody testing was conducted in emergency medical service agencies and 27 hospitals in the Detroit, Michigan, USA, metropolitan area during May-June 2020. Of 16,403 participants, 6.9% had SARS-CoV-2 antibodies. In adjusted analyses, seropositivity was associated with exposure to SARS-CoV-2-positive household members (adjusted odds ratio [aOR] 6.18, 95% CI 4.81-7.93) and working within 15 km of Detroit (aOR 5.60, 95% CI 3.98-7.89). Nurse assistants (aOR 1.88, 95% CI 1.24-2.83) and nurses (aOR 1.52, 95% CI 1.18-1.95) had higher likelihood of seropositivity than physicians. Working in a hospital emergency department increased the likelihood of seropositivity (aOR 1.16, 95% CI 1.002-1.35). Consistently using N95 respirators (aOR 0.83, 95% CI 0.72-0.95) and surgical facemasks (aOR 0.86, 95% CI 0.75-0.98) decreased the likelihood of seropositivity.