Association of E484K Spike Protein Mutation With Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection in Vaccinated Persons: Maryland, January-May 2021.

Among 9048 people infected with SARS-CoV-2 between January and May 2021 in Maryland, in regression-adjusted analysis, SARS-CoV-2 viruses carrying the spike protein mutation E484K were disproportionately prevalent among persons infected after full vaccination against COVID-19 compared with infected persons who were not fully vaccinated (aOR, 1.96; 95% CI: 1.36-2.83).

Linked Clusters of SARS-CoV-2 Variant B.1.351 - Maryland, January-February 2021.

In late January 2021, a clinical laboratory notified the Maryland Department of Health (MDH) that the SARS-CoV-2 variant of concern B.1.351 had been identified in a specimen collected from a Maryland resident with COVID-19 (1). The SARS-CoV-2 B.1.351 lineage was first identified in South Africa (2) and might be neutralized less effectively by antibodies produced after vaccination or natural infection with other strains (3-6). To limit SARS-CoV-2 chains of transmission associated with this index patient, MDH used contact tracing to identify the source of infection and any linked infections among other persons. The investigation identified two linked clusters of SARS-CoV-2 infection that included 17 patients. Three additional specimens from these clusters were sequenced; all three had the B.1.351 variant and all sequences were closely related to the sequence from the index patient's specimen. Among the 17 patients identified, none reported recent international travel or contact with international travelers. Two patients, including the index patient, had received the first of a 2-dose COVID-19 vaccination series in the 2 weeks before their likely exposure; one additional patient had a confirmed SARS-CoV-2 infection 5 months before exposure. Two patients were hospitalized with COVID-19, and one died. These first identified linked clusters of B.1.351 infections in the United States with no apparent link to international travel highlight the importance of expanding the scope and volume of genetic surveillance programs to identify variants, completing contact investigations for SARS-CoV-2 infections, and using universal prevention strategies, including vaccination, masking, and physical distancing, to control the spread of variants of concern.

Genetic diversity and virulence profiles of Listeria monocytogenes recovered from bulk tank milk, milk filters, and milking equipment from dairies in the United States (2002 to 2014).

Unpasteurized dairy products are known to occasionally harbor Listeria monocytogenes and have been implicated in recent listeriosis outbreaks and numerous sporadic cases of listeriosis. However, the diversity and virulence profiles of L. monocytogenes isolates recovered from these products have not been fully described. Here we report a genomic analysis of 121 L. monocytogenes isolates recovered from milk, milk filters, and milking equipment collected from bovine dairy farms in 19 states over a 12-year period. In a multi-virulence-locus sequence typing (MVLST) analysis, 59 Virulence Types (VT) were identified, of which 25% were Epidemic Clones I, II, V, VI, VII, VIII, IX, or X, and 31 were novel VT. In a multi-locus sequence typing (MLST) analysis, 60 Sequence Types (ST) of 56 Clonal Complexes (CC) were identified. Within lineage I, CC5 and CC1 were among the most abundant, and within lineage II, CC7 and CC37 were the most abundant. Multiple CCs previously associated with central nervous system and maternal-neonatal infections were identified. A genomic analysis identified variable distribution of virulence markers, Listeria pathogenicity islands (LIPI) -1, -3, and -4, and stress survival island-1 (SSI-1). Of these, 14 virulence markers, including LIPI-3 and -4 were more frequently detected in one lineage (I or II) than the other. LIPI-3 and LIPI-4 were identified in 68% and 28% of lineage I CCs, respectively. Results of this analysis indicate that there is a high level of genetic diversity among the L. monocytogenes present in bulk tank milk in the United States with some strains being more frequently detected than others, and some being similar to those that have been isolated from previous non-dairy related outbreaks. Results of this study also demonstrate significant number of strains isolated from dairy farms encode virulence markers associated with severe human disease.