Japanese scientists to start clinical trial of Ebola vaccine

An Ebola virus virion is seen from a colorized transmission electron micrograph image. According to a report on Thursday, May, 17, 2018, Congo's Ebola outbreak has spread to a city, a worrying shift as the risk of infection is more easily passed on in densely populated urban areas.


By THE JAPAN NEWS-YOMIURI Published: December 5, 2019

A Japanese research team will start a clinical trial this month of the nation's first domestically developed vaccine for Ebola, a step toward developing a new weapon in the fight against the deadly disease.

After the vaccine's safety has been confirmed through the trial in Japan, its impact will be examined from next year in places such as central Africa, where Ebola is still found.

Since an outbreak of Ebola in western Africa in 2014, cases of the virus have also emerged in the United States and other countries. While no cases have been confirmed in Japan so far, domestic steps to prepare for such a situation are urgently being taken, for such reasons as the increasing number of foreign visitors to the nation.

The vaccine is initially expected to be administered to medical care workers who would be involved in treating and looking after an Ebola patient detected in the nation. The vaccine's main purposes are to ensure medical treatment systems are maintained and to help prevent the disease from spreading within Japan.

The research team, whose members include Yoshihiro Kawaoka, a virology expert at the University of Tokyo, developed the vaccine based on an Ebola virus that had been genetically altered so it could not multiply or reproduce. The vaccine's safety was boosted when combined with the use of special drugs, which stripped the virus of its infectious capacity.

Monkeys that were given the vaccine were then infected with a potentially fatal dose of the Ebola virus, but none displayed symptoms of the disease and all survived. The vaccine's safety and effectiveness was confirmed through such tests on animals.

The clinical test will be conducted on a total of 30 healthy men at the university's Institute of Medical Science. After being given two vaccinations four weeks apart, the men will be regularly examined for side effects and whether they have developed immunity to the Ebola virus. If the vaccine is proven to be safe, the research team plans to work with pharmaceutical companies and conduct clinical trials to confirm the vaccine is effective in the Democratic Republic of the Congo and other nations where Ebola is found.

Ebola virus vaccines have been partly put to practical use overseas. However, serious side effects such as severe joint pain after being vaccinated have been reported. Accordingly, the development of a safer, easier-to-make vaccine has been called for.

"This vaccine is much safer because it eliminates the virus' infectious capacity and prevents it from multiplying inside the body," Kawaoka said. "Having an effective vaccine in Japan is important for ensuring the safety of the public."

Nagasaki University Prof. Jiro Yasuda, a virology expert, said it was conceivable the vaccine was very safe because it was made based on a virus that had lost its ability to cause infections. "The start of a clinical trial in Japan is a big step in the fight against Ebola," Yasuda added.

Ebola hemorrhagic fever is a viral infection found in 1976 in central Africa with an average fatality rate of 50%, according to the World Health Organization. About 10 days after being infected, the patient usually develops symptoms such as increasingly severe vomiting and diarrhea, and eventually could suffer from multiple organ failure and bleeding. About 11,000 people died during an outbreak in western Africa from 2014 to 2016. Ebola is still found in the Democratic Republic of Congo, where at least 3,000 people have been infected and about 2,000 have died. 

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