Background SARS-CoV-2, the virus that causes COVID-19 disease, was first identified in Wuhan, China in December 2019, with subsequent worldwide spread. The first U.S. cases were identified in January 2020. Methods To determine if SARS-CoV-2 reactive antibodies were present in sera prior to the first identified case in the U.S. on January 19, 2020, residual archived samples from 7,389 routine blood donations collected by the American Red Cross from December 13, 2019 to January 17, 2020, from donors resident in nine states (California, Connecticut, Iowa, Massachusetts, Michigan, Oregon, Rhode Island, Washington, and Wisconsin) were tested at CDC for anti-SARS-CoV-2 antibodies. Specimens reactive by pan-immunoglobulin (pan Ig) enzyme linked immunosorbent assay (ELISA) against the full spike protein were tested by IgG and IgM ELISAs, microneutralization test, Ortho total Ig S1 ELISA, and receptor binding domain / Ace2 blocking activity assay. Results Of the 7,389 samples, 106 were reactive by pan Ig. Of these 106 specimens, 90 were available for further testing. Eighty four of 90 had neutralizing activity, 1 had S1 binding activity, and 1 had receptor binding domain / Ace2 blocking activity >50%, suggesting the presence of anti-SARS-CoV-2-reactive antibodies. Donations with reactivity occurred in all nine states. Conclusions These findings suggest that SARS-CoV-2 may have been introduced into the United States prior to January 19, 2020.

IMPORTANCEAs self-collected home antigen tests become widely available, a better understanding of their performance during the course of SARS-CoV-2 infection is needed. OBJECTIVE To evaluate the diagnostic performance of home antigen tests compared with reverse transcription-polymerase chain reaction (RT-PCR) and viral culture by days from illness onset, as well as user acceptability. DESIGN, SETTING, AND PARTICIPANTS This prospective cohort study was conducted from January to May 2021 in San Diego County, California, and metropolitan Denver, Colorado. The convenience sample included adults and children with RT-PCR-confirmed infection who used self-collected home antigen tests for 15 days and underwent at least 1 nasopharyngeal swab for RT-PCR, viral culture, and sequencing. EXPOSURES SARS-CoV-2 infection. MAIN OUTCOMES AND MEASURES The primary outcome was the daily sensitivity of home antigen tests to detect RT-PCR-confirmed cases. Secondary outcomes included the daily percentage of antigen test, RT-PCR, and viral culture results that were positive, and antigen test sensitivity compared with same-day RT-PCR and cultures. Antigen test use errors and acceptability were assessed for a subset of participants. RESULTS This study enrolled 225 persons with RT-PCR-confirmed infection (median [range] age, 29 [1-83] years; 117 female participants [52%]; 10 [4%] Asian, 6 [3%] Black or African American, 50 [22%] Hispanic or Latino, 3 [1%] Native Hawaiian or Other Pacific Islander, 145[64%] White, and 11 [5%] multiracial individuals) who completed 3044 antigen tests and 642 nasopharyngeal swabs. Antigen test sensitivity was 50% (95% CI, 45%-55%) during the infectious period, 64% (95% CI, 56%-70%) compared with same-day RT-PCR, and 84% (95% CI, 75%-90%) compared with same-day cultures. Antigen test sensitivity peaked 4 days after illness onset at 77% (95% CI, 69%-83%). Antigen test sensitivity improved with a second antigen test 1 to 2 days later, particularly early in the infection. Six days after illness onset, antigen test result positivity was 61% (95% CI, 53%-68%). Almost all (216 [96%]) surveyed individuals reported that they would be more likely to get tested for SARS-CoV-2 infection if home antigen tests were available over the counter. CONCLUSIONS AND RELEVANCEThe results of this cohort study of home antigen tests suggest that sensitivity for SARS-CoV-2 was moderate compared with RT-PCR and high compared with viral culture. The results also suggest that symptomatic individuals with an initial negative home antigen test result for SARS-CoV-2 infection should test again 1 to 2 days later because test sensitivity peaked several days after illness onset and improved with repeated testing.

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According to the National Statistical Service of Greece, single-parent families, which emerged after divorce, in 2011 occupied an important place among other family types, endangering a large number of children to display behavioral problems and poor school performance. The purpose of the present study was to investigate the effects of divorce on preschool children. Specifically, we studied the behavior problems and academic performance of children from single-parent families compared with children from nuclear families according to teachers' views. The research sample consisted of 314 students from various urban and suburban parts of Greece, for which their 118 preschool teachers completed the "Pupil Behavior Rating Scale" (PBRS) and a questionnaire with demographic characteristics and data of themselves, their students and their students' parents. The results of the research showed statistically significant correlations between 1) the type of family and occurrence of behavioral problems and 2) the type of family and school performance of the two student groups (single parenthood-nuclear). According to the findings of the present study, it appears that the family pattern affects the emotional development and school progress of children. For this reason, bearing always in mind that each family is unique, they are of particular importance: the assurance of a structured family environment (quality relationships of the members), the regular communication with parents built upon relationships of respect and trust, and finally, the social support and assistance of competent institutions to single-parent families.

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