Among healthy, young adults, risk for subsequent infection among seropositive participants about one-fifth of that for seronegative participants<\/p>\n<\/h3>\n
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MONDAY, April 19, 2021 (HealthDay News) — Among healthy, young adults, those who are seropositive rather than seronegative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have a reduced risk for subsequent SARS-CoV-2 infection — about one-fifth the risk for infection compared with seronegative participants, according to a study published online April 15 in The Lancet Respiratory Medicine<\/em>.<\/p>\n Andrew G. Letizia, M.D., from the Naval Medical Research Center in Silver Spring, Maryland, enrolled predominantly male U.S. Marine recruits, aged 18 to 20 years, following a two-week unsupervised quarantine at home. After the home quarantine period, participants were assessed for baseline SARS-CoV-2 immunoglobulin G (IgG) positivity and underwent a supervised two-week quarantine period. Participants with three negative results during quarantine and a baseline serum serology test were included in the study; both seropositive and seronegative groups underwent three SARS-CoV-2 tests at weeks 2, 4, and 6 in a prospective study.<\/p>\n The researchers enrolled 3,249 participants, of whom 98 percent continued into the two-week quarantine period. Ninety-five percent of participants were followed during the prospective study period. Of 189 seropositive participants, during the six-week follow-up, 10 percent had at least one positive test for SARS-CoV-2 (1.1 cases per person-year). Among 2,247 seronegative participants, 48 percent tested positive (6.2 cases per person-year). The incidence rate ratio was 0.18. Infection was more likely among seropositive recruits with lower versus higher baseline full-length spike protein IgG titers (hazard ratio, 0.45). Compared with infected seronegative participants, infected seropositive participants had viral loads that were about 10 times lower.<\/p>\n “Our results indicate that although antibodies induced by infection are largely protective, they do not guarantee effective immunity against subsequent infection,” the authors write.<\/p>\n One author disclosed financial ties to Co-Diagnostics; two authors have filed a patent regarding serological assays for SARS-CoV-2.<\/p>\n Abstract\/Full Text<\/a><\/p>\n