One of the most recurring questions these days, regarding the coronavirus, is whether it will be possible to have a vaccine in a short time.
EL TIEMPO consulted Alberto Buitrago, an internist and infectologist at the San José Hospital; Javier Cote, Master in Molecular Biology and Biotechnology and PhD in Immunology, and Arley Gómez, PhD in Biomedical Sciences and Director of Research at the University Foundation for Health Sciences.
How do vaccines work?
The goal of a vaccine is to prevent the immune system from developing an effective and long-lasting response against the offending agent, in this case Covid-19. Vaccines can contain virus proteins or peptides that stimulate the generation of protective antibodies by the individual against the virus.
Some vaccines use the complete infectious agent, but in a state of inactivation -also called attenuation-, which allows it to be introduced into the human body to generate an immune response without translating this exposure into disease.
Vaccines induce protective immunity in humans when antibodies are developed that block adhesion and entry of the virus to human cells using a receptor. The receptor for human cells is expressed in epithelial cells of the lung, intestine, kidney, and blood vessels.
Are there vaccines against coronavirus?
Not yet. Currently, there is no coronavirus vaccine, nor is there any therapeutic molecule or antiviral medication that prevents or has a neutralizing or destructive action against the COVID-19 virus. In the case of human pathogenic coronaviruses, the vaccine must be directed against the viral molecule that Covid-19 uses as a ligation, which is called Protein S.
What is the difficulty in developing a vaccine in a short time?
Every vaccine must go through a process of development in the laboratory and then go on to demonstrate its safety and efficacy in human clinical trials before being approved by government authorities, such as the FDA in the United States or, Invima, in Colombia, to be later commercialized. So far, animal models with inactivated or attenuated virus approaches have been developed for both SARS-Cov and MERS-Cov, in addition to other methodologies proposed by scientists such as DNA plasmids, viral vectors and even nanoparticles, but without the availability of vaccines for clinical use.
How is the virus different from others that have caused similar infections in the past?
Covid-19 is the third coronavirus to emerge as a pathogen in the past two decades. SARS CoV-1 (SARS), MERS-CoV and SARS CoV-2 (Covid-19). Although viruses belong to the same family, there are differences between them. SARS infection is more deadly; however, it managed to be contained in just 6 months, while the Covid-19 is rapidly spreading worldwide.
There are more asymptomatic patients with Covid-19 and the rate of transmission through asymptomatic patients is higher than SARS; however, to date, the mortality rate with Covid-19 (4%) is lower than that of SARS Cov-1 (9.5%) and MERS-Cov.
It is important to mention that Covid-19 mortality can vary from country to country. On the other hand, Covid-19 has at least one mortality rate 10 times higher than the Influenza virus.
One of the problems observed with the predecessor coronaviruses (HCoV-229E, HCoV-OC43, HCoV-NL63, and HCoV-HKU1), which cause the common cold and other upper respiratory diseases, is that the immunity obtained by humans when infections occur is very short, which means that they can be reinfected very quickly.
Can you talk about a period in which you can have a vaccine?
There are currently approximately 35 prophylactic vaccines in development against Covid-19. The type of vaccine to be tested must show consistency in stimulating the immune response so that it can be considered effective in large populations. From this process, which involves highly specialized laboratories, key elements must be evaluated that will determine the possibility of using them massively in humans; for example, safety in terms of side effects, large-scale development costs, ease of administration, number of applications required, and the numerical probability of achieving good protection, as well as the duration of this immunity. In the case of the coronavirus vaccine it could take a year and a half before being widely used in the population, which would be a record time.
NICOLÁS BUSTAMANTE HERNÁNDEZ
SCIENCE EDITOR
@ NicolásB23
nicbus @ eltiempo.com
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