The WHO published a list of vaccines in the making against the new coronavirus on April 4, 2020. There is a total of 62 vaccine candidates, two of which are already at the stage of clinical testing.
Each potential vaccine is based on different operating principles and is in different stages of development and clinical testing, reported Forbes. András Falus, an immunologist and academic, explained the development process.
Phases of clinical testing
Medicines and vaccines have to go through a number of experimental and trial phases before they can get to the market.
- Preclinical phase: includes all steps in vaccine development that do not involve human subjects, from modelling the expected effect to animal testing.
- Clinical Phase 1: the new vaccine is tested for the first time in healthy volunteers, and possible side effects are being examined.
- Clinical phase 2: a specific, small group of patients is already tested to see if the vaccine is effective, and the optimal dose is attempted to be determined.
- Clinical phase 3: a larger number of patients are tested for the vaccine’s safety, efficiency, side effects, and the vaccine also goes through comparative examinations with other medicines. The new vaccine must be monitored for two years after introduction for safety reasons.
- Putting it on the market: if the vaccine has passed the necessary tests, developers can start getting the necessary permits from the appropriate authorities to start selling it.
- Clinical phase 4: the vaccine is compared to other products after having been put on the market, looking at long-term effectiveness and safety, cost-effectiveness and possible rare side effects.
Restrictions to help slow the pandemic down are indefinitely extended in Hungary.
Keep up with news on the new coronavirus HERE and the newest developments in Hungary HERE.
Vaccines show the immune system something about the pathogen, which helps the immune system to prepare for a possible later infection. This “something” can be various things. Here are the possibilities based on Tamás Ferenczi’s “About Vaccines – Based on Facts.”
- Vaccines containing live weakened virus, such as the measles mumps rubella (MMR) vaccine or the oral polio vaccine (OPV, Sabin drops), usually provide strong immunity and do not require adjuvants, a substance that boosts natural immunity. There is a constant risk, however, that in some vaccines, even weakened ones could cause diseases. For the new coronavirus, Codagenix and the Serum Institute of India have begun experiments to develop a live attenuated vaccine.
- Inactivated vaccines, like classic influenza vaccinations, contain the entire virus in an inactivated form. It generally gives less effective immunity, is combined with adjuvants, but there are no risks of live pathogen vaccines. Only one company, Sinovac, is experimenting with the new coronavirus using such technology, inactivating it with formaldehyde.
- Viral vector-based vaccines are not currently in such routine use. Their working principle is to introduce the gene encoding parts of the virus that are actually dangerous with a harmless virus with limited infectivity, and the body’s infected cells themselves produce the molecules that make up the immune system that characterise the dangerous virus. For the new coronavirus, several studies have been done to produce a non-replicating viral vector. At least 10 companies are trying to come up with a viral vector-based vaccine, mostly with adenovirus vectors.
- With inactivated unit vaccines, such as the already existing hepatitis B vaccine, a characteristic portion of the virus is delivered with the vaccine in an inactivated form. Like hepatitis B, the new coronavirus may need a protein-based solution targeting the N (nucleocapsid), but especially S (spike) protein of the virus. This seems promising because the S protein is responsible for binding to the ACE2 receptor on the surface of host cells, which is the entry point for the coronavirus. At least 15 companies are trying to develop in this direction, usually using patented technologies, but typically targeting protein S.
- Nucleic acid-based vaccines seem to be one of the most innovative solutions, but actually, they have been experimented with for a long time (e.g. HIV) and have not been translated into clinical use so far. In this case, a gene encoding a protein of the pathogen is introduced in the form of DNA or mRNA with a plasmid, i.e. a non-nuclear hereditary material. The advantage of such vaccines is that they generate a stable immune response in principle, do not cause the disease, and are simple and easy to manufacture. At least 11 companies are working to apply the technology to the new coronavirus.
The pandemic is really bringing out the creativity in people. In one of the 60 vaccines in preclinical development, the company is trying to grow the vaccine with a plant.
András Falus mentioned another promising method, the so-called holistic vaccine-development. It is based on IT methods and artificial intelligence. Chinese researchers determined the new coronavirus’s gene-sequence in January. They predicted that 26 proteins are needed for the virus to be efficient. They are trying to find antagonists from human protein databases with A.I. that will efficiently protect against these proteins in the virus and the virus itself.
He also mentioned a procedure in development, which would have the S protein of the new coronavirus introduced to the body along with influenza viruses through the nose so that local immunisation could hopefully start.