Ebola vaccine trial finds good antibody persistence for VSV-EBOV
In a new study on the Ebola vaccine that has already shown effectiveness in an earlier phase 3 trial during West Africa's outbreak, researchers found that antibodies persist at least for a year and that the vaccine was well tolerated. A team from NewLink Genetics and Merck—the two groups that have licensed the vaccine developed by the Public Health Agency of Canada—published their phase 1b findings Jun 9 in The Lancet Infectious Diseases.
The trial took place at eight US study sites starting at the end of 2014 and involved 512 healthy adults in two cohorts who received one of seven different VSV-EBOV doses; 418 received the vaccine and 94 got placebo. Early studies had hinted at a possible drop-off in protection, and in one earlier phase 1 study, some study participants reported arthralgia after receiving the vaccine.
According to the new findings that cover 360 days of data, the 2× 107 plaque-forming-unit dose used in the outbreak clinical setting appeared to be well tolerated; most adverse events were mild-to-moderate, occurred soon after vaccination, were of short duration, and were more common at the higher vaccine doses. Nineteen (4.5%) reported temporary joint pain that didn't seem related to the dose, but did seem to be related to increased age. The group saw robust antibody responses that have been reported by other groups, and at all doses tested, neutralizing antibodies persisted for at least 1 year after immunization.
In a related commentary, two infectious disease experts from the University of New Mexico said the study's strength is that it shows good persistence of antibody responses after vaccination, which could increase vaccine usefulness for healthcare workers and people in endemic areas who are likely to be exposed to Ebola over long periods. The authors are Elizabeth Clarke, PhD, and Steven Bradfute, PhD, both with infectious diseases division of the university's Center for Global Health. They also said the study sheds more light on safety concerns, revealing that transient arthritis was observed at a much lower rate than in earlier Ebola vaccine studies.
The antibody and dose responses shown in the study are important steps forward in creating a safe and effective vaccine against Ebola, the two wrote, adding that more efforts are needed to standardize T-cell and antibody tests used in vaccine trials to help make comparisons between vaccines.
Jun 9 Lancet Infect Dis abstract
Jun 9 Lancet Infect Dis commentary
In other Ebola vaccine developments, the World Health Organization (WHO) recently issued draft guidance for using Ebola vaccine in outbreak response settings. The report has a May date on it and was written by multiple partners who were part of the Global Ebola Vaccine Implementation Team. Before finalizing the document, which covers use of a licensed Ebola vaccine, authors are asking for comments by Jun 30.
WHO draft guidance call for comments
Two more Brazilian states report yellow fever
According from the latest update from the European Centre for Disease Prevention and Control (ECDC), two new states in Brazil, Mato Grosso and Distrito Federal, have reported their first cases of yellow fever in 2017.
There are now nine states with confirmed yellow fever cases in Brazil. The latest outbreak began in January of this year in Minas Gerais and Espirito Santo. From Jan 6 to May 31, the ECDC said there have been 1,311 cases of yellow fever (519 suspected and 792 confirmed), including 311 deaths (37 suspected and 274 confirmed). The case-fatality rate is 34.6% among confirmed cases.
The ECDC said five other countries in South America have reported human cases of yellow fever this year: Peru (17), Colombia (6), Bolivia (1), Ecuador (1), and Suriname (1).
Jun 12 ECDC report
Afghanistan reports another wild poliovirus case
Afghanistan recently reported its fourth wild poliovirus case of the year, the Afghanistan Times reported today, citing the country's health ministry.
The patient is a 5-month-old boy from Helmand province who is experiencing paralysis. The illness is the second this year from Helmand province. According to the report, the area has been covered by recent vaccination campaigns, but the boy's parents had refused to immunize him.
The country is one of three where wild poliovirus is endemic. According to a Jun 7 update from the Global Polio Eradication Initiative (GPEI), the last case from Afghanistan involved a patient from Kunduz province with a Feb 21 paralysis onset. GPEI noted that most areas of the country are polio-free and recent efforts are targeting ongoing transmission in the Quetta-Kandahar corridor. In 2016, Afghanistan reported 16 cases.
Jun 12 Afghanistan Times story
Jun 7 GPEI update