Background We report on the safety and immunogenicity of V591, a measles vector-based SARS-CoV-2 vaccine candidate. Methods In this multicentre, randomised, placebo-controlled, double-blind, phase 1/2 trial, healthy adults with no history of COVID-19 disease were assigned to intramuscular injection of V591 or placebo (4:1 ratio). In part 1, younger adults (18-55 years) received V591 median tissue culture infectious dose (TCID 50 )-levels of 1×10 5 or 1×10 6 or placebo, 56 days apart. In part 2, younger and older (>55 years) adults received a single dose of one of four (10 4 /10 5 /10 6 /10 7 ) or one of two (10 5 /10 6 ) V591 TCID 50 levels, respectively, or placebo. Primary outcome: safety/tolerability. Secondary outcome: humoral immunogenicity. ClinicalTrials.gov: NCT04498247. Findings From August–December 2020, 444 participants were screened and 263 randomised (210 V591; 53 placebo); 262 received at least one and 10 received two doses of V591 or placebo. Adverse events were experienced by 140/209 (67.0%) V591 dose-group participants and 37/53 (69.8%) placebo-group participants following injection 1; most frequent were fatigue (57 [27.3%] vs 20 [37.7%]), headache (57 [27.3%] vs 19 [35.8%]), myalgia (35 [16.7%] vs 10 [18.9%]), and injection-site pain (35 [16.7%] vs 4 [7.5%]). No deaths nor vaccine-related serious adverse events occurred. At Day 29, no anti-SARS-CoV-2 spike serum neutralising antibody and IgG-responses were identified in placebo or the three lower V591 dose-groups; responses were detected with V591 1×10 7 TCID 50 , although titres were lower than convalescent serum. Interpretation V591 was generally well tolerated, but immunogenicity was insufficient to warrant continued development. Funding Merck Sharp & Dohme, Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.

BACKGROUND The genetic heterogeneity of Leishmania parasites is a major factor responsible for the wide variety of Leishmania-associated manifestations. Consequently, understanding the genetic make-up of Leishmania species using suitable molecular markers is an important component of realising local and regional scale disease risk. The cytochrome b (cytb) is frequently used to type New World Leishmania species. However, its potential to discriminate Leishmania species and variants requires further evaluation.OBJECTIVES To explore the capacity of cytb gene to identify New World Leishmania species and variants and to develop an approach able to type local Leishmania species and variants.METHODS We retrieved 360 partial and complete Leishmania cytb gene sequences publicly available in GenBank database to study all single nucleotide polymorphisms (SNPs) across the cytb gene that differentiate New World Leishmania species. This information was used to develop an approach based upon the polymorphisms found in a DNA segment of 948bp. We also compared the typing results found with this technique with the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) profiling obtained using HSP70 gene as target. One hundred Panamanian isolates were used to both typed Leishmania species and assess local genetic variability.FINDINGS We found complete agreement between our cytb approach and the PCR-RFLP profiling method based on HSP70 for Leishmania species identification. Ninety-two isolates were identified as L. panamensis, although other Viannia species were found circulating at a lower frequency. Three L. panamensis haplotypes were identified in Panamanian provinces. We also provide an initial report of L. guyanensis haplotypes circulating in Panama.MAIN CONCLUSIONS Cytb gene sequence encompasses key main SNPs that aid to identify Leishmania species. The cytb approach developed with this information was able to identify and assess genetic variability of local Leishmania species found in this study. Key words: leishmaniasis -cytochrome b gene -haplotypes -Leishmania panamensis -Leishmania guyanensis -PanamaLeishmaniasis, a neglected tropical disease transmitted by female sandflies and caused by kinetoplastic protozoa parasites of the genus Leishmania, is endemic in 98 countries worldwide. Due to the high number of cases and its geographical expansion, the World Health Organization (WHO) considers leishmaniasis as an emerging/ reemerging vector borne parasitic disease. (1) Regarding its impact on public health, leishmaniasis has an estimated annual incidence of 2.0 million cases and an approximated prevalence of 12,000,000 cases. (2) In addition, this disease is responsible for 20,000 to 40,000 deaths occurring in rural and suburban populations all year round. (1,2) Visceral and tegumentary leishmaniasis are the main clinical forms of the disease which show different clinical expressions depending upon the species of Leishmania responsible for the disease, the genetic background and immunological status of ...

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