April 14 | Daily COVID-19 LST Report

Transmission & Prevention

· Binding and neutralization antibody titers after a single vaccine dose in previously infected with SARS-CoV-2 were found to be higher. Researchers of the Institute of Human Virology at the University of Maryland School of Medicine, Baltimore present a serosurvey of 59 healthcare workers who, prior to receiving the first dose of an mRNA SARS-CoV-2 vaccine, were categorized as SARS-CoV-2 IgG negative, IgG positive asymptomatic, and IgG positive symptomatic. At days 0, 7, and 14, plasma was obtained and analyzed to quantify median reciprocal half-maximal binding antibody titers to the spike trimer. At 0, 7, and 14 days they found higher overall titers in both the asymptomatic IgG+ (208, 29 364, and 34 033) and the symptomatic IgG+ (302, 32 301, and 35 460) groups compared to the IgG negative group (<50, <50, and 924). The authors discuss that this data can help to inform vaccination strategies employing single-dose prioritization.

· Antibodies appear to persist through 6 months after the second dose of mRNA-1273 vaccine for COVID-19. Doctorate researchers from the National Institute of Allergy and Infectious Diseases (NIAID) and Emory University School of Medicine investigated 33 healthy adults 6 months after the second dose of Moderna mRNA-1273 COVID-19 vaccine for durability and neutralizing effect of elicited antibodies. An enzyme-linked immunosorbent assay (ELISA) was utilized to measure antibodies by geometric mean endpoint titers (GMTs) and reported that antibodies remained high in all age groups, but 50% inhibitory dilution (ID50) GMTs were lower in 56 to 70 years of age (p = 0.02) and >71 years of age (p = 0.004) than in those 18 to 55 years of age. This study suggests the continued use of the vaccination for SARS-CoV-2 given the presence of antibodies 180 days after vaccination.

· Emergence of a novel SARS-CoV-2 variant was found in Southern California. Pathology and lab medicine experts from Cedars-Sinai Medical Center in Los Angeles sequenced nasopharyngeal samples collected from 192 patients positive for SARS-CoV-2 between November to December 2020 and conducted phylogenetic analysis using representative genomes from the open source genomic database Nextstrain. They discovered a novel strain with five mutations (CAL.20G) in 22% of all samples (40/185) with a descendent cluster (CAL.20C) accounting for 36.4% (67/185) of cases in Los Angeles. While the CAL.20C strain's significance is unknown, it has now been identified in 25 other states leading the authors to encourage ongoing surveillance for SARS-CoV-2 variants.

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