However, these studies include individuals in different age populations and worse clinical severity, in some cases requiring hospitalization, than participants with this study. weeks PO, of whom 97.3% (111/114) remained positive, with significantly decreased levels, at 10 weeks PO. Neutralizing activity was recognized in all sera from SARS-CoV-2 IgG positive participants tested (n=38) at 6 and 10 weeks PO, without significant loss between time points. IgG and IgA antibodies against SARS-CoV-2 RBD, S1, S2, and the nucleocapsid (N) protein, as well neutralization activity, were generally similar between those participants that experienced asymptomatic illness or slight disease. A multiplex assay including S proteins from SARS-CoV-2 and related zoonotic and human being endemic betacoronaviruses exposed a positive correlation for polyclonal cross-reactivity to S after SARS-CoV-2 illness. Overall, young adults that experienced asymptomatic or slight Lentinan SARS-CoV-2 illness developed similar humoral reactions, with no decrease in neutralizing activity at least up to 10 weeks after illness. Keywords: SARS-COV-2, antibodies, outbreak, young adults, COVID-19 Intro Humoral immune Lentinan reactions to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are Lentinan induced within a few days after illness in most infected individuals (1C4). Neutralizing antibodies to SARS-CoV-2 are stable for at least 5-8 weeks after illness (5C7). A high proportion of SARS-CoV-2 infections, particularly in young adults, happens in the absence of symptoms (8, 9). Although individuals with asymptomatic infections develop SARS-CoV-2 antibodies, it has been reported the magnitude of their response is less than for symptomatic individuals (10, 11). Given the elevated proportion of asymptomatic and slight infections in young populations, and their high potential for transmission (12), characterizing the period and efficacy of their immune response is critical to establishing efficient public health steps for military teaching as well as local communities. In the context of military settings, infectious diseases such as SARS-CoV-2 can lead to loss of workdays for young adults, degrading teaching and readiness (13C16). Additionally, the?normal countermeasures to control outbreaks, such as quarantine and reinforced hygiene requirements, may be?insufficient for Coronavirus Disease 2019 (COVID-19) prevention (12). Between March 15 and April 15, 2020, multiple recruits at Marine Corp Recruit Depot Parris Island (MCRDPI) presented with acute respiratory symptoms including cough, fever, muscle aches, shortness of breath, and sore throat. A total of 147 participants that were identified as infected with, or exposed to, SARS-CoV-2, and were isolated from the rest of the Marine recruits in teaching, were included in this study. Here, we characterize the serological reactions to SARS-CoV-2 along with other betacoronaviruses during an early outbreak in US Marine recruits over a 28 day time period, approximately 6 and 10 weeks after SARS-CoV-2 exposure, and assess the relationship with disease manifestation among a Marine recruit teaching population. Methods Cohort and Data Collection 147 participants that were isolated during an outbreak of respiratory illness between March 15 and April 15 (outbreak windows), 2020, were enrolled in this study. The criteria for inclusion with this study were: i) becoming 18 years or older at the time of the study enrollment and ii) potential or confirmed exposure during the outbreak windows, defined as ii.a) suspected COVID-19 by having met clinical case definition according to Centers for Disease Control and Prevention (17), or ii.b) having confirmed SARS-CoV-2 illness using BioFire COVID-19 test (BioFire Defense, Salt Lake City, UT, USA) as part of medical care during the outbreak windows, or ii.c) being in contact with suspected or confirmed SARS-CoV-2 positive individuals and were deemed individuals under investigation. As part of the protocol, the?investigators reviewed the electronic medical records Lentinan for the consented participants. Enrollment in the study was approximately 6 weeks (4-8 weeks range) post-outbreak (PO), and Lentinan a subsequent follow-up occurred 4 weeks later on (10 weeks PO, 8-12 weeks range). At both time points, the Rabbit Polyclonal to ATF-2 (phospho-Ser472) participants were asked to accomplish a short questionnaire to self-report symptoms of respiratory illness and contact with anyone with respiratory symptoms. Demographic info, such as age, sex, ethnicity, and smoking history was collected at the initial enrollment. Signs and symptoms included in the questionnaires were: fever (>100.4), subjective fever, chills, muscle mass aches, fatigue, runny nose, sore throat, cough, shortness of breath, nausea or vomiting, headache, taste or smell decreased ability, abdominal pain, diarrheal, or others. Collection of Biological Specimens At each time point (6 and 10 weeks PO), blood was collected using serum separator tubes (SST) and serum separated by centrifugation (1500 x g for 10?min). Aliquots of serum were.