To better understand the advances in the fight against the new coronavirus, we have prepared this summary that contains information about the vaccines against COVID-19 that are being studied. The race to produce an effective SARS-CoV-2 vaccine has been intense. Researchers are using several technologies, some of which have never been used in vaccines before.
The various types of vaccines against COVID-19
All vaccines are designed to expose the individual to an antigen. Although the exposed antigen is not capable of causing disease, it causes an immune response that can block or kill the virus when the individual is exposed to it.
There are at least 8 different types of vaccines being tested. The type of vaccine depends on the type of virus or the viral part being used:
Viral Vector Vaccine
Nucleic Acid Vaccine
Vaccines against COVID-19
This type of vaccine can use the weakened or inactivated virus. In this sense, in a weakened virus vaccine, the virus undergoes processes until it acquires mutations that make it less capable of causing disease.
On the other hand, in inactivated virus vaccines, the virus is modified with chemical particles or heat, in such a way that it becomes unable to cause infection.
At least 7 groups are developing vaccines that use the virus itself. They can use the weakened or inactivated virus. This is a type of vaccine that already exists.
For example, measles and polio vaccines use the virus itself in its composition. However, vaccines that use viruses require extensive safety testing.
In Beijing, Sinovac Biotech is testing a vaccine with inactivated SARS-CoV-2 in humans.
Viral Vector Vaccine
In vaccines that use viral vectors, a virus such as measles or adenovirus is genetically modified to produce coronavirus proteins.
These viruses are weakened and cannot cause disease. There are two types: those that can still replicate within cells and those that cannot because the main genes have been disabled.
In order to develop this type of vaccine, approximately 25 groups are working with viral vector vaccines.
Viral vector vaccine
Nucleic Acid Vaccines
In this type of vaccine, the nucleic acid is ed into human cells, which produce copies of some virus protein. In short, most of these vaccines encode the virus's spike protein.
At least 20 teams are working on the development of vaccines that use genetic information viral DNA or RNA.
They are easy to develop vaccines, as they only involve genetic material, not the virus. However, this is a technology that has never been used in any currently licensed vaccine, so it is not yet proven effective.
In this type of vaccine, coronavirus proteins are injected directly into the body. Likewise, fragments or shells of proteins that mimic the structure of the virus can also be used.
At least 28 teams are working using vaccines that use protein subunits.
Most of them focus on the spike protein, since it plays a key role in the process of virus entry into the cell, through the connection with the ACE2 receptor.
This type of vaccine requires adjuvants to stimulate the immune system, as well as multiple doses.
Protein spike vaccine
Another way is to use virus-like particles, which consist of a "shell" containing the external viral structure, but without the inner content.
These particles are not capable of causing infection because they do not have genetic material the virus. It has the capacity to generate a strong immune response, but they are difficult to produce.
Five teams are working on the development of this type of vaccine.
Virus-like particle vaccine
The Race for Vaccines against COVID-19
We saw above that several groups are engaged in producing different types of vaccines against COVID-19. The joint work of several countries, institutions and companies wishing to arrive at the definitive solution against the pandemic we face.
Most vaccine research efforts are being led (70%) by industrial or private companies. The production of a vaccine can take years.
However, due to the current emergency situation, the researchers are accelerating the steps and intend to have a vaccine ready in 18 months.