The coronavirus disease 2019 (COVID-19) is caused by a novel coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is associated with several fatal cases worldwide. The rapid spread of this pathogen and the increasing number of cases highlight the urgent development of vaccines. Among the technologies available for vaccine development, DNA vaccination is a promising alternative to conventional vaccines. Since its discovery in the 1990s, it has been of great interest because of its ability to elicit both humoral and cellular immune responses while showing relevant advantages regarding producibility, stability, and storage. This review aimed to summarize the current knowledge and advancements on DNA vaccines against COVID-19, particularly those in clinical trials.

Neglected tropical diseases, including zoonoses such as leptospirosis, have a major impact on rural and poor urban communities, particularly in developing countries. This has led to major investment in antipoverty vaccines that focus on diseases that influence public health and thereby productivity. While the true, global, impact of leptospirosis is unknown due to the lack of adequate laboratory diagnosis, the WHO estimates that incidence has doubled over the last 15 years to over 1 million cases that require hospitalization every year. Leptospirosis is caused by pathogenic Leptospira spp. and is spread through direct contact with infected animals, their urine or contaminated water and soil. Inactivated leptospirosis vaccines, or bacterins, are approved in only a handful of countries due to the lack of heterologous protection (there are > 250 pathogenic Leptospira serovars) and the serious side-effects associated with vaccination. Currently, research has focused on recombinant vaccines, a possible solution to these problems. However, due to a lack of standardised animal models, rigorous statistical analysis and poor reproducibility, this approach has met with limited success. We evaluated a subunit vaccine preparation, based on a conserved region of the leptospiral immunoglobulin-like B protein (LigB(131–645)) and aluminium hydroxide (AH), in the hamster model of leptospirosis. The vaccine conferred significant protection (80.0–100%, P < 0.05) against mortality in vaccinated animals in seven independent experiments. The efficacy of the LigB(131–645)/AH vaccine ranged from 87.5–100% and we observed sterile immunity (87.5–100%) among the vaccinated survivors. Significant levels of IgM and IgG were induced among vaccinated animals, although they did not correlate with immunity. A mixed IgG1/IgG2 subclass profile was associated with the subunit vaccine, compared to the predominant IgG2 profile seen in bacterin vaccinated hamsters. These findings suggest that LigB(131–645) is a vaccine candidate against leptospirosis with potential ramifications to public and veterinary health.

No abstract

Introduction The World Health Organization (WHO) recommends vaccination against Sars Cov-2 coronavirus to mitigate COVID-19 pandemic. On December 29th, the Argentine Ministry of Health started a vaccination plan with the Sputnik V vaccine emphasizing the registration of the Events Supposedly Attributed to Vaccines and Immunizations (ESAVI) in the National Surveillance System. The aim of this study is to determine the safety of this vaccine. Methods In an ongoing cohort study, health professionals from Hospital Italiano de Buenos Aires vaccinated with the first component of the Sputnik V vaccine (a rAd26 vector-based) were followed up. Safety at 72 hs was analysed from a self-report form. Local and systemic reactions were characterized as mild, moderate and severe. Incident rates were calculated per 1000 person-hours by age groups and gender. Adjusted hazard ratio and 95% Confidence Interval (HR; 95%CI) is obtained by Cox Regression Model. Results 707 health professionals (mean age 35, 67% female) were vaccinated, response rate was 96,6% and 71,3% reported at least one ESAVI. Rate was 6.3 per 1.000 person-hours. Among local reactions, 54% reported pain at the injection site, 11% redness and swelling. Among systemic reactions 40% reported fever, 5% diarrhea and 68% new or worsened muscle pain. Five percent had serious adverse events that required medical evaluation and one inpatient. ESAVI rate was higher among females (65.4% vs 50%; HR 1.38, 95%CI 1.13-5.38) and in younger than 55 years-old (72.8% vs 32%; HR 2.66, 95%CI 1.32-1.68). Conclusion Active surveillance on safety for vaccines with emergency approval is mandatory. This study shows high rates of local and systemic reactions however early serious events were rare. Short term safety is supported by these preliminary findings. Studies on long term safety and efficacy, accoding sex and age, are needed.

No abstract