Vaccine developers are pursuing a number of different approaches: inactivated vaccines, live vaccines and DNA vaccines. What’s the difference between them? And when will one finally be ready?
Since the start of this year, pharmaceutical companies and institutes worldwide have been conducting research to try to find a vaccine against the coronavirus SARS-CoV-2. So far, the German Association of Research-Based Pharmaceutical Companies (VFA) has identified 115 different vaccine projects, while the World Health Organization (WHO) count is 102.
The main focus of research is on three types of vaccines: live, inactivated, and DNA or mRNA vaccines. But what is the difference between them?
The starting point for a live vaccine is a virus that is known, but harmless. It does not cause disease, but is able to multiply within the cells of our bodies. This is the vector which then triggers an immune response.
The way this works is, for example, when vaccine developers use genetic engineering to disguise these viruses as SARS-CoV-2 viruses by giving them a corresponding surface protein. This is a particularly good approach when seeking to combat new types of pathogen.
When a person is given the vaccine, their body builds up immunity. This protection then enables it to ward off actual infection by the disease. A vector vaccine of this kind was used against smallpox, and the first approved Ebola vaccine is also based on a vector virus.
These vaccines contain selected viral proteins or inactivated viruses. These are pathogens that have been killed.
The dead viruses can no longer multiply, but the body still recognizes them as intruders, so the body's defense system ensures that antibodies are produced. The vaccinated individual does not develop the disease.
This method uses tried and tested technology. It is already used in vaccines against diseases such as influenza, polio, whooping cough, hepatitis B, and tetanus.
Compared to inactivated vaccines with viral proteins, the advantage of gene-based vaccines is that the pharmaceutical industry can produce them quickly. It will have to be able to do this, because once a vaccine against COVID-19 is found, billions of doses will need to be made available to people all over the world in the shortest possible time.
The gene-based vaccines contain pure genetic information in the form of coronavirus DNA or mRNA. Individual parts of genetic information from the pathogen are packed into nanoparticles and introduced into cells. Once the vaccine is in the body, it should form harmless viral proteins that build up immune protection.
So far, though, no such vaccine exists on the market. They are still in development, with various companies and institutes conducting research into them. The first vaccine to have received Phase I approval in Germany is an mRNA vaccine.
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The time frame
The question on everyone's lips: When will an effective vaccine become available? This depends not just on the time it takes for a vaccine to be developed, tested and approved. Once it passes the laboratory tests, the next step is to test it on animals. After this, vaccine candidates are tested in several phases, to determine: 1) Are they safe? 2) Do they help to build an immune response? 3) Do they work in practice?
Once all these hurdles have been overcome, there is another: Manufacturers must produce the vaccine, in very large quantities. There is hardly any company that has this kind of capacity.
Some vaccines are already being developed in parallel, so that companies can be prepared in advance for possible production. Capacity is made available even though the vaccine has not yet completed all the phases of testing. Nonetheless, there are hardly any doctors who anticipate the complete development and approval of a vaccine before 2021.
At an online international donor conference in Brussels on May 4, world leaders pledged over €7.4 billion ($8.07 billion) for the development of vaccines, drugs and tests. Participants were invited by Ursula von der Leyen, the president of the European Commission. The idea behind it is that vaccinations can only be successful if everyone in the world has access to them.
One of the key institutions supporting many of the ongoing research projects is CEPI, the Coalition for Epidemic Preparedness Innovation. The CEPI Foundation was established at the 2016 World Economic Forum (WEF) in Davos to help countries around the world develop vaccines. After the experience with Ebola, its founders wanted to ensure that poorer countries in particular were not defenseless against epidemics.
To this end, the governments of Norway and India joined forces with the Bill and Melinda Gates Foundation, the WEF, and the British Wellcome Trust. More and more countries now support the foundation with public funds, including Germany, Australia, Belgium, Canada, Denmark, Ethiopia, Japan, Saudi Arabia, the Netherlands, and Switzerland. CEPI is currently helping to fund the development of at least eight vaccines by various companies.