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Item BNT162b2 mRNA Vaccination Against Coronavirus Disease 2019 is Associated With a Decreased Likelihood of Multisystem Inflammatory Syndrome in Children Aged 5-18 Years-United States, July 2021 - April 2022(Oxford University Press, 2023) Zambrano, Laura D.; Newhams, Margaret M.; Olson, Samantha M.; Halasa, Natasha B.; Price, Ashley M.; Orzel, Amber O.; Young, Cameron C.; Boom, Julie A.; Sahni, Leila C.; Maddux, Aline B.; Bline, Katherine E.; Kamidani, Satoshi; Tarquinio, Keiko M.; Chiotos, Kathleen; Schuster, Jennifer E.; Cullimore, Melissa L.; Heidemann, Sabrina M.; Hobbs, Charlotte V.; Nofziger, Ryan A.; Pannaraj, Pia S.; Cameron, Melissa A.; Walker, Tracie C.; Schwartz, Stephanie P.; Michelson, Kelly N.; Coates, Bria M.; Flori, Heidi R.; Mack, Elizabeth H.; Smallcomb, Laura; Gertz, Shira J.; Bhumbra, Samina S.; Bradford, Tamara T.; Levy, Emily R.; Kong, Michele; Irby, Katherine; Cvijanovich, Natalie Z.; Zinter, Matt S.; Bowens, Cindy; Crandall, Hillary; Hume, Janet R.; Patel, Manish M.; Campbell, Angela P.; Randolph, Adrienne G.; Overcoming COVID-19 Investigators; Pediatrics, School of MedicineBackground: Multisystem inflammatory syndrome in children (MIS-C), linked to antecedent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is associated with considerable morbidity. Prevention of SARS-CoV-2 infection or coronavirus disease 2019 (COVID-19) by vaccination might also decrease MIS-C likelihood. Methods: In a multicenter, case-control, public health investigation of children ages 5-18 years hospitalized from 1 July 2021 to 7 April 2022, we compared the odds of being fully vaccinated (2 doses of BNT162b2 vaccine ≥28 days before hospital admission) between MIS-C case-patients and hospital-based controls who tested negative for SARS-CoV-2. These associations were examined by age group, timing of vaccination, and periods of Delta and Omicron variant predominance using multivariable logistic regression. Results: We compared 304 MIS-C case-patients (280 [92%] unvaccinated) with 502 controls (346 [69%] unvaccinated). MIS-C was associated with decreased likelihood of vaccination (adjusted OR [aOR]: .16; 95% CI: .10-.26), including among children ages 5-11 years (aOR: .22; 95% CI: .10-.52), ages 12-18 years (aOR: .10; 95% CI: .05-.19), and during the Delta (aOR: .06; 95% CI: .02-.15) and Omicron (aOR: .22; 95% CI: .11-.42) variant-predominant periods. This association persisted beyond 120 days after the second dose (aOR: .08; 95% CI: .03-.22) in 12-18-year-olds. Among all MIS-C case-patients, 187 (62%) required intensive care unit admission and 280 (92%) vaccine-eligible case-patients were unvaccinated. Conclusions: Vaccination with 2 doses of BNT162b2 is associated with reduced likelihood of MIS-C in children ages 5-18 years. Most vaccine-eligible hospitalized patients with MIS-C were unvaccinated.Item BNT162b2 Protection against the Omicron Variant in Children and Adolescents(Massachusetts Medical Society, 2022) Price, Ashley M.; Olson, Samantha M.; Newhams, Margaret M.; Halasa, Natasha B.; Boom, Julie A.; Sahni, Leila C.; Pannaraj, Pia S.; Irby, Katherine; Bline, Katherine E.; Maddux, Aline B.; Nofziger, Ryan A.; Cameron, Melissa A.; Walker, Tracie C.; Schwartz, Stephanie P.; Mack, Elizabeth H.; Smallcomb, Laura; Schuster, Jennifer E.; Hobbs, Charlotte V.; Kamidani, Satoshi; Tarquinio, Keiko M.; Bradford, Tamara T.; Levy, Emily R.; Chiotos, Kathleen; Bhumbra, Samina S.; Cvijanovich, Natalie Z.; Heidemann, Sabrina M.; Cullimore, Melissa L.; Gertz, Shira J.; Coates, Bria M.; Staat, Mary A.; Zinter, Matt S.; Kong, Michele; Chatani, Brandon M.; Hume, Janet R.; Typpo, Katri V.; Maamari, Mia; Flori, Heidi R.; Tenforde, Mark W.; Zambrano, Laura D.; Campbell, Angela P.; Patel, Manish M.; Randolph, Adrienne G.; Overcoming Covid-19 Investigators; Pediatrics, School of MedicineBackground: Spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 (omicron) variant, which led to increased U.S. hospitalizations for coronavirus disease 2019 (Covid-19), generated concern about immune evasion and the duration of protection from vaccines in children and adolescents. Methods: Using a case-control, test-negative design, we assessed vaccine effectiveness against laboratory-confirmed Covid-19 leading to hospitalization and against critical Covid-19 (i.e., leading to receipt of life support or to death). From July 1, 2021, to February 17, 2022, we enrolled case patients with Covid-19 and controls without Covid-19 at 31 hospitals in 23 states. We estimated vaccine effectiveness by comparing the odds of antecedent full vaccination (two doses of BNT162b2 messenger RNA vaccine) at least 14 days before illness among case patients and controls, according to time since vaccination for patients 12 to 18 years of age and in periods coinciding with circulation of B.1.617.2 (delta) (July 1, 2021, to December 18, 2021) and omicron (December 19, 2021, to February 17, 2022) among patients 5 to 11 and 12 to 18 years of age. Results: We enrolled 1185 case patients (1043 [88%] of whom were unvaccinated, 291 [25%] of whom received life support, and 14 of whom died) and 1627 controls. During the delta-predominant period, vaccine effectiveness against hospitalization for Covid-19 among adolescents 12 to 18 years of age was 93% (95% confidence interval [CI], 89 to 95) 2 to 22 weeks after vaccination and was 92% (95% CI, 80 to 97) at 23 to 44 weeks. Among adolescents 12 to 18 years of age (median interval since vaccination, 162 days) during the omicron-predominant period, vaccine effectiveness was 40% (95% CI, 9 to 60) against hospitalization for Covid-19, 79% (95% CI, 51 to 91) against critical Covid-19, and 20% (95% CI, -25 to 49) against noncritical Covid-19. During the omicron period, vaccine effectiveness against hospitalization among children 5 to 11 years of age was 68% (95% CI, 42 to 82; median interval since vaccination, 34 days). Conclusions: BNT162b2 vaccination reduced the risk of omicron-associated hospitalization by two thirds among children 5 to 11 years of age. Although two doses provided lower protection against omicron-associated hospitalization than against delta-associated hospitalization among adolescents 12 to 18 years of age, vaccination prevented critical illness caused by either variant.Item Effectiveness of BNT162b2 (Pfizer-BioNTech) mRNA Vaccination Against Multisystem Inflammatory Syndrome in Children Among Persons Aged 12–18 Years — United States, July–December 2021(U.S. Department of Health & Human Services, 2022-01-14) Zambrano, Laura D.; Newhams, Margaret M.; Olson, Samantha M.; Halasa, Natasha B.; Price, Ashley M.; Boom, Julie A.; Sahni, Leila C.; Kamidani, Satoshi; Tarquinio, Keiko M.; Maddux, Aline B.; Heidemann, Sabrina M.; Bhumbra, Samina S.; Bline, Katherine E.; Nofziger, Ryan A.; Hobbs, Charlotte V.; Bradford, Tamara T.; Cvijanovich , Natalie Z.; Irby, Katherine; Mack, Elizabeth H.; Cullimore, Melissa L.; Pannaraj, Pia S.; Kong, Michele; Walker, Tracie C.; Gertz, Shira J.; Michelson, Kelly N.; Cameron, Melissa A.; Chiotos, Kathleen; Maamari, Mia; Schuster, Jennifer E.; Orzel, Amber O.; Patel, Manish M.; Campbell, Angela P.; Randolph, Adrienne G.; Overcoming COVID-19 Investigators; Pediatrics, School of MedicineItem Effectiveness of BNT162b2 Vaccine against Critical Covid-19 in Adolescents(Massachusetts Medical Society, 2022) Olson, Samantha M.; Newhams, Margaret M.; Halasa, Natasha B.; Price, Ashley M.; Boom, Julie A.; Sahni, Leila C.; Pannaraj, Pia S.; Irby, Katherine; Walker, Tracie C.; Schwartz, Stephanie P.; Maddux, Aline B.; Mack, Elizabeth H.; Bradford, Tamara T.; Schuster, Jennifer E.; Nofziger, Ryan A.; Cameron, Melissa A.; Chiotos, Kathleen; Cullimore, Melissa L.; Gertz, Shira J.; Levy, Emily R.; Kong, Michele; Cvijanovich, Natalie Z.; Staat, Mary A.; Kamidani, Satoshi; Chatani, Brandon M.; Bhumbra, Samina S.; Bline, Katherine E.; Gaspers, Mary G.; Hobbs, Charlotte V.; Heidemann, Sabrina M.; Maamari, Mia; Flori, Heidi R.; Hume, Janet R.; Zinter, Matt S.; Michelson, Kelly N.; Zambrano, Laura D.; Campbell, Angela P.; Patel, Manish M.; Randolph, Adrienne G.; Pediatrics, School of MedicineBackground: The increasing incidence of pediatric hospitalizations associated with coronavirus disease 2019 (Covid-19) caused by the B.1.617.2 (delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United States has offered an opportunity to assess the real-world effectiveness of the BNT162b2 messenger RNA vaccine in adolescents between 12 and 18 years of age. Methods: We used a case-control, test-negative design to assess vaccine effectiveness against Covid-19 resulting in hospitalization, admission to an intensive care unit (ICU), the use of life-supporting interventions (mechanical ventilation, vasopressors, and extracorporeal membrane oxygenation), or death. Between July 1 and October 25, 2021, we screened admission logs for eligible case patients with laboratory-confirmed Covid-19 at 31 hospitals in 23 states. We estimated vaccine effectiveness by comparing the odds of antecedent full vaccination (two doses of BNT162b2) in case patients as compared with two hospital-based control groups: patients who had Covid-19-like symptoms but negative results on testing for SARS-CoV-2 (test-negative) and patients who did not have Covid-19-like symptoms (syndrome-negative). Results: A total of 445 case patients and 777 controls were enrolled. Overall, 17 case patients (4%) and 282 controls (36%) had been fully vaccinated. Of the case patients, 180 (40%) were admitted to the ICU, and 127 (29%) required life support; only 2 patients in the ICU had been fully vaccinated. The overall effectiveness of the BNT162b2 vaccine against hospitalization for Covid-19 was 94% (95% confidence interval [CI], 90 to 96); the effectiveness was 95% (95% CI, 91 to 97) among test-negative controls and 94% (95% CI, 89 to 96) among syndrome-negative controls. The effectiveness was 98% against ICU admission and 98% against Covid-19 resulting in the receipt of life support. All 7 deaths occurred in patients who were unvaccinated. Conclusions: Among hospitalized adolescent patients, two doses of the BNT162b2 vaccine were highly effective against Covid-19-related hospitalization and ICU admission or the receipt of life support. (Funded by the Centers for Disease Control and Prevention.).Item Effectiveness of Maternal Vaccination with mRNA COVID-19 Vaccine During Pregnancy Against COVID-19–Associated Hospitalization in Infants Aged <6 Months — 17 States, July 2021–January 2022(Center for Disease Control, 2022-02-18) Halasa, Natasha B.; Olson, Samantha M.; Staat, Mary A.; Newhams, Margaret M.; Price, Ashley M.; Boom, Julie A.; Sahni, Leila C.; Cameron, Melissa A.; Pannaraj, Pia S.; Bline, Katherine E.; Bhumbra, Samina S.; Bradford, Tamara T.; Chiotos, Kathleen; Coates, Bria M.; Cullimore, Melissa L.; Cvijanovich, Natalie Z.; Flori, Heidi R.; Gertz, Shira J.; Heidemann, Sabrina M.; Hobbs, Charlotte V.; Hume, Janet R.; Irby, Katherine; Kamidani, Satoshi; Kong, Michele; Levy, Emily R.; Mack, Elizabeth H.; Maddux, Aline B.; Michelson, Kelly N.; Nofziger, Ryan A.; Schuster, Jennifer E.; Schwartz, Stephanie P.; Smallcomb, Laura; Tarquinio, Keiko M.; Walker, Tracie C.; Zinter, Matt S.; Gilboa, Suzanne M.; Polen, Kara N.; Campbell, Angela P.; Randolph, Adrienne G.; Patel, Manish M.; Overcoming COVID-19 Investigators; Overcoming COVID-19 Network; Pediatrics, School of MedicineCOVID-19 vaccination is recommended for persons who are pregnant, breastfeeding, trying to get pregnant now, or who might become pregnant in the future, to protect them from COVID-19.§ Infants are at risk for life-threatening complications from COVID-19, including acute respiratory failure (1). Evidence from other vaccine-preventable diseases suggests that maternal immunization can provide protection to infants, especially during the high-risk first 6 months of life, through passive transplacental antibody transfer (2). Recent studies of COVID-19 vaccination during pregnancy suggest the possibility of transplacental transfer of SARS-CoV-2-specific antibodies that might provide protection to infants (3-5); however, no epidemiologic evidence currently exists for the protective benefits of maternal immunization during pregnancy against COVID-19 in infants. The Overcoming COVID-19 network conducted a test-negative, case-control study at 20 pediatric hospitals in 17 states during July 1, 2021-January 17, 2022, to assess effectiveness of maternal completion of a 2-dose primary mRNA COVID-19 vaccination series during pregnancy against COVID-19 hospitalization in infants. Among 379 hospitalized infants aged <6 months (176 with COVID-19 [case-infants] and 203 without COVID-19 [control-infants]), the median age was 2 months, 21% had at least one underlying medical condition, and 22% of case- and control-infants were born premature (<37 weeks gestation). Effectiveness of maternal vaccination during pregnancy against COVID-19 hospitalization in infants aged <6 months was 61% (95% CI = 31%-78%). Completion of a 2-dose mRNA COVID-19 vaccination series during pregnancy might help prevent COVID-19 hospitalization among infants aged <6 months.Item Factors Associated With COVID-19 Non-vaccination in Adolescents Hospitalized Without COVID-19(Oxford University Press, 2023) Sahni, Leila C.; Price, Ashley M.; Olson, Samantha M.; Newhams, Margaret M.; Pannaraj, Pia S.; Maddux, Aline B.; Halasa, Natasha B.; Bline, Katherine E.; Cameron, Melissa A.; Schwartz, Stephanie P.; Walker, Tracie C.; Irby, Katherine; Chiotos, Kathleen; Nofziger, Ryan A.; Mack, Elizabeth H.; Smallcomb, Laura; Bradford, Tamara T.; Kamidani, Satoshi; Tarquinio, Keiko M.; Cvijanovich, Natalie Z.; Schuster, Jennifer E.; Bhumbra, Samina S.; Levy, Emily R.; Hobbs, Charlotte V.; Cullimore, Melissa L.; Coates, Bria M.; Heidemann, Sabrina M.; Gertz, Shira J.; Kong, Michele; Flori, Heidi R.; Staat, Mary A.; Zinter, Matt S.; Hume, Janet R.; Chatani, Brandon M.; Gaspers, Mary G.; Maamari, Mia; Randolph, Adrienne G.; Patel, Manish M.; Boom, Julie A.; Pediatrics, School of MedicineBackground: Pfizer-BioNTech COVID-19 vaccine received emergency use authorization for persons ≥ 16 years in December 2020 and for adolescents 12-15 years in May 2021. Despite the clear benefits and favorable safety profile, vaccine uptake in adolescents has been suboptimal. We sought to assess factors associated with COVID-19 non-vaccination in adolescents 12-18 years of age. Methods: Between June 1, 2021 and April 29, 2022, we assessed factors associated with COVID-19 non-vaccination in hospitalized adolescents ages 12-18 years enrolled in the Overcoming COVID-19 vaccine effectiveness network. Demographic characteristics and clinical information were captured through parent interviews and/or electronic medical record abstraction; COVID-19 vaccination was assessed through documented sources. We assessed associations between receipt of the COVID-19 vaccine and demographic and clinical factors using univariate and multivariable logistic regression and estimated adjusted odds ratios (aOR) for each factor associated with non-vaccination. Results: Among 1665 hospitalized adolescents without COVID-19, 56% were unvaccinated. Unvaccinated adolescents were younger (median age 15.1 years vs. 15.4 years, p < .01) and resided in areas with higher social vulnerability index (SVI) scores (median 0.6 vs 0.5, p < .001) than vaccinated adolescents. Residence in the Midwest [aOR 2.60 (95% CI: 1.80, 3.79)] or South [aOR 2.49 (95% CI: 1.77, 3.54)] US census regions, rarely or never receiving influenza vaccine [aOR 5.31 (95% CI: 3.81, 7.47)], and rarely or never taking precautions against COVID-19 [aOR 3.17 (95% CI: 1.94, 5.31)] were associated with non-vaccination against COVID-19. Conclusions: Efforts to increase COVID-19 vaccination of adolescents should focus on persons with geographic, socioeconomic, and medical risk factors associated with non-vaccination.Item Investigating Health Disparities Associated With Multisystem Inflammatory Syndrome in Children After SARS-CoV-2 Infection(Wolters Kluwer, 2022) Zambrano, Laura D.; Ly, Kathleen N.; Link-Gelles, Ruth; Newhams, Margaret M.; Akande, Manzilat; Wu, Michael J.; Feldstein, Leora R.; Tarquinio, Keiko M.; Sahni, Leila C.; Riggs, Becky J.; Singh, Aalok R.; Fitzgerald, Julie C.; Schuster, Jennifer E.; Giuliano, John S., Jr.; Englund, Janet A.; Hume, Janet R.; Hall, Mark W.; Osborne, Christina M.; Doymaz, Sule; Rowan, Courtney M.; Babbitt, Christopher J.; Clouser, Katharine N.; Horwitz, Steven M.; Chou, Janet; Patel, Manish M.; Hobbs, Charlotte; Randolph, Adrienne G.; Campbell, Angela P.; Overcoming COVID-19 Investigators; Pediatrics, School of MedicineBackground: Multisystem inflammatory syndrome in children (MIS-C) is a postinfectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related complication that has disproportionately affected racial/ethnic minority children. We conducted a pilot study to investigate risk factors for MIS-C aiming to understand MIS-C disparities. Methods: This case-control study included MIS-C cases and SARS-CoV-2-positive outpatient controls less than 18 years old frequency-matched 4:1 to cases by age group and site. Patients hospitalized with MIS-C were admitted between March 16 and October 2, 2020, across 17 pediatric hospitals. We evaluated race, ethnicity, social vulnerability index (SVI), insurance status, weight-for-age and underlying medical conditions as risk factors using mixed effects multivariable logistic regression. Results: We compared 241 MIS-C cases with 817 outpatient SARS-CoV-2-positive at-risk controls. Cases and controls had similar sex, age and U.S. census region distribution. MIS-C patients were more frequently previously healthy, non-Hispanic Black, residing in higher SVI areas, and in the 95th percentile or higher for weight-for-age. In the multivariable analysis, the likelihood of MIS-C was higher among non-Hispanic Black children [adjusted odds ratio (aOR): 2.07; 95% CI: 1.23-3.48]. Additionally, SVI in the 2nd and 3rd tertiles (aOR: 1.88; 95% CI: 1.18-2.97 and aOR: 2.03; 95% CI: 1.19-3.47, respectively) were independent factors along with being previously healthy (aOR: 1.64; 95% CI: 1.18-2.28). Conclusions: In this study, non-Hispanic Black children were more likely to develop MIS-C after adjustment for sociodemographic factors, underlying medical conditions, and weight-for-age. Investigation of the potential contribution of immunologic, environmental, and other factors is warranted.Item Maternal Vaccination and Risk of Hospitalization for Covid-19 among Infants(Massachusetts Medical Society, 2022) Halasa, Natasha B.; Olson, Samantha M.; Staat, Mary A.; Newhams, Margaret M.; Price, Ashley M.; Pannaraj, Pia S.; Boom, Julie A.; Sahni, Leila C.; Chiotos, Kathleen; Cameron, Melissa A.; Bline, Katherine E.; Hobbs, Charlotte V.; Maddux, Aline B.; Coates, Bria M.; Michelson, Kelly N.; Heidemann, Sabrina M.; Irby, Katherine; Nofziger, Ryan A.; Mack, Elizabeth H.; Smallcomb, Laura; Schwartz, Stephanie P.; Walker, Tracie C.; Gertz, Shira J.; Schuster, Jennifer E.; Kamidani, Satoshi; Tarquinio, Keiko M.; Bhumbra, Samina S.; Maamari, Mia; Hume, Janet R.; Crandall, Hillary; Levy, Emily R.; Zinter, Matt S.; Bradford, Tamara T.; Flori, Heidi R.; Cullimore, Melissa L.; Kong, Michele; Cvijanovich, Natalie Z.; Gilboa, Suzanne M.; Polen, Kara N.; Campbell, Angela P.; Randolph, Adrienne G.; Patel, Manish M.; Overcoming Covid-19 Investigators; Pediatrics, School of MedicineBackground: Infants younger than 6 months of age are at high risk for complications of coronavirus disease 2019 (Covid-19) and are not eligible for vaccination. Transplacental transfer of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after maternal Covid-19 vaccination may confer protection against Covid-19 in infants. Methods: We used a case-control test-negative design to assess the effectiveness of maternal vaccination during pregnancy against hospitalization for Covid-19 among infants younger than 6 months of age. Between July 1, 2021, and March 8, 2022, we enrolled infants hospitalized for Covid-19 (case infants) and infants hospitalized without Covid-19 (control infants) at 30 hospitals in 22 states. We estimated vaccine effectiveness by comparing the odds of full maternal vaccination (two doses of mRNA vaccine) among case infants and control infants during circulation of the B.1.617.2 (delta) variant (July 1, 2021, to December 18, 2021) and the B.1.1.259 (omicron) variant (December 19, 2021, to March 8, 2022). Results: A total of 537 case infants (181 of whom had been admitted to a hospital during the delta period and 356 during the omicron period; median age, 2 months) and 512 control infants were enrolled and included in the analyses; 16% of the case infants and 29% of the control infants had been born to mothers who had been fully vaccinated against Covid-19 during pregnancy. Among the case infants, 113 (21%) received intensive care (64 [12%] received mechanical ventilation or vasoactive infusions). Two case infants died from Covid-19; neither infant's mother had been vaccinated during pregnancy. The effectiveness of maternal vaccination against hospitalization for Covid-19 among infants was 52% (95% confidence interval [CI], 33 to 65) overall, 80% (95% CI, 60 to 90) during the delta period, and 38% (95% CI, 8 to 58) during the omicron period. Effectiveness was 69% (95% CI, 50 to 80) when maternal vaccination occurred after 20 weeks of pregnancy and 38% (95% CI, 3 to 60) during the first 20 weeks of pregnancy. Conclusions: Maternal vaccination with two doses of mRNA vaccine was associated with a reduced risk of hospitalization for Covid-19, including for critical illness, among infants younger than 6 months of age.Item Risk Factors for Multisystem Inflammatory Syndrome in Children: A Case-Control Investigation(Wolters Kluwer, 2023) Zambrano, Laura D.; Wu, Michael J.; Martin, Lora; Malloch, Lacy; Chen, Sabrina; Newhams, Margaret M.; Kucukak, Suden; Son, Mary Beth; Sanders, Cameron; Patterson, Kayla; Halasa, Natasha; Fitzgerald, Julie C.; Leroue, Matthew K.; Hall, Mark; Irby, Katherine; Rowan, Courtney M.; Wellnitz, Kari; Sahni, Leila C.; Loftis, Laura; Bradford, Tamara T.; Staat, Mary; Babbitt, Christopher; Carroll, Christopher L.; Pannaraj, Pia S.; Kong, Michele; Schuster, Jennifer E.; Chou, Janet; Patel, Manish M.; Randolph, Adrienne G.; Campbell, Angela P.; Hobbs, Charlotte V.; Overcoming COVID-19 investigators; Pediatrics, School of MedicineBackground: In a 2020 pilot case-control study using medical records, we reported that non-Hispanic Black children were more likely to develop multisystem inflammatory syndrome in children (MIS-C) after adjustment for sociodemographic factors and underlying medical conditions. Using structured interviews, we investigated patient, household, and community factors underlying MIS-C likelihood. Methods: MIS-C case patients hospitalized in 2021 across 14 US pediatric hospitals were matched by age and site to outpatient controls testing positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within 3 months of the admission date. Caregiver interviews queried race/ethnicity, medical history, and household and potential community exposures 1 month before MIS-C hospitalization (case-patients) or after SARS-CoV-2 infection (controls). We calculated adjusted odds ratios (aOR) using mixed-effects multivariable logistic regression. Results: Among 275 case patients and 496 controls, race/ethnicity, social vulnerability and patient or family history of autoimmune/rheumatologic disease were not associated with MIS-C. In previously healthy children, MIS-C was associated with a history of hospitalization for an infection [aOR: 4.8; 95% confidence interval (CI): 2.1-11.0]. Household crowding (aOR: 1.7; 95% CI: 1.2-2.6), large event attendance (aOR: 1.7; 95% CI: 1.3-2.1), school attendance with limited masking (aOR: 2.6; 95% CI: 1.1-6.6), public transit use (aOR: 1.8; 95% CI: 1.4-2.4) and co-resident testing positive for SARS-CoV-2 (aOR: 2.2; 95% CI: 1.3-3.7) were associated with increased MIS-C likelihood, with risk increasing with the number of these factors. Conclusions: From caregiver interviews, we clarify household and community exposures associated with MIS-C; however, we did not confirm prior associations between sociodemographic factors and MIS-C.