While more than 100 types of vaccines against Covid-19 are being studied around the world, the search for drugs that activate our immune defences against dangerous viral diseases, such as Ebola in particular – the viral haemorrhagic fever that causes the death of more than 50% of those infected – is proceeding at an intense pace. A vaccine against Ebola, developed by Merck, was approved in November 2019 by the European Medicines Agency (EMA), and has already been used “on the field” to protect more than 250,000 people in the Democratic Republic of the Congo. However, research is continuing with the aim of achieving even more effective results against the different types of Ebola virus (the vaccine developed by Merck protects people from the Zaire species currently found in the Congo, but not against the strain of the virus known as Sudan, the source of seven outbreaks in other areas). At the same time researchers are also studying methods of making it easier to administer the drug: the vaccine approved by EMA, for example, must be kept refrigerated, which is not always possible in African countries where the haemorrhagic fever is widespread.
Among the new possible vaccines, a new “prototype” developed by the U.S. Army Medical Research Institute of Infectious Diseases is delivering promising results. As reported in the scientific journal Vaccine, this new type of vaccine consists of an Ebola virus protein duplicated in the lab (and, therefore, not the whole virus, as is the case with the Merck vaccine), which is then strengthened with an adjuvant Advax, developed in Australia by Vaxine, a company created by the National Health Sciences Center in Canberra. The new vaccine, write the researchers, has a highly protective effect on laboratory animals, even after only one injection, and remains stable also in the heat. Furthermore, this protection seems to be long-lasting, and if the antibodies produced by an animal are transferred to another non-vaccinated and infected animal, they appear to produce a therapeutic effect (as is the case in Covid-19 sufferers treated with the plasma of recovered patients). Hence, there are grounds for continuing this research. Other pharmaceutical companies, like GlaxoSmithKline and Johnson & Johnson, are also working in this area.
The Ebola virus, as we know, continues to cause regular hotbeds of infection in different areas of Africa. One of the most serious, emerging between 2014 and 2016, caused thousands of deaths in Guinea, Sierra Leone and Liberia. In 2018 a new epidemic broke out in the Democratic Republic of the Congo, causing great concern, even if it was possible in this case to administer the first experimental vaccines. The disease, however, has not yet been beat in the Congo.
The combination of a synthetic viral protein and an adjuvant capable of strengthening the response of the immune system, tested against Ebola, is also being studied to stem Covid-19. Vaxine is exploring this avenue, as well as other large companies in the sector: tests on animals are at a very advanced stage and there are also plans to start testing on humans.