The scourge of risk associated with the increase in cases, hospitals saturated by covid-19 and deaths seems like a return to the starting box. The nightmare of the increase in incidence in Europe and of new variants such as omicron is back. However, as much as the mutant drift of the virus calls into question the effectiveness of vaccines, there is an individual and population immune background that has irremediably changed the level of damage that SARS-CoV-2 can cause us, to each of us and society as a whole.
The main current vaccines against SARS-CoV-2 are designed to generate adaptive immunity against the surface protein of the virus. This immunity takes the form of a wide variety of clones of B lymphocytes and their corresponding antibodies, as well as T lymphocytes. However, it goes beyond the neutralizing antibodies that prevent the virus from entering our cells. That this system fails to prevent infection is not the end of the world.
Lacking effective neutralizing antibodies does not imply that other antibodies may have other functions. One function, for example, is to cooperate in the identification of infected cells and to aid in their destruction. These serve as flags that our immune system puts on infected cells to be detected and attacked by other cells such as cells. natural killer (NK), neutrophils, monocytes, and macrophages.
Furthermore, T lymphocytes are capable of recognizing protein fragments presented in infected cells through type I major histocompatibility complexes (MHC-I). Therefore, having a good repertoire of T lymphocytes will allow the selective destruction of infected cells.
The effectiveness of vaccines
The efficacy of vaccines can be classified in three ways: based on their efficacy in preventing infection, efficacy in preventing disease, and efficacy in preventing death.
Current vaccination strategies are effective in preventing infection during the first months, but the drop in antibodies reduces the possible blockage of entry of the virus. Despite this, for now vaccines remain effective in preventing serious illness and death. An exception to this protection from disease would be those who are immunocompromised.
In this scenario, and given the evolutionary capacity of the virus, it is likely that we do not have effective tools to completely contain the infection, but we do have its most dramatic consequences.
This implies that, sooner or later, we can all become infected.
However, the way of coping with this infection changes in those people who have been infected or vaccinated compared to those who are not infected or vaccinated. The coronavirus finds subjects where it can replicate in people with previous immunity, but it does so with more difficulties compared to those who have not been vaccinated or previously infected.
As the population faces the virus in a natural way, the stimulation of the production of antibodies and T cells against all the virus proteins, not only against the S protein, will allow us to increase our immune capacity against the virus. and future versions of it.
In this way, the stimulation of the defenses against conserved regions of the 29 proteins described of the virus will allow us to face SARS-CoV-2 with an efficiency similar to that we have against other respiratory viruses that visit us on a recurring basis.
The most common viral respiratory infections are caused by viruses such as adenoviruses, coronaviruses HKU1, NL63, 229E and OC43, human metapneumovirus, rhinovirus, influenza viruses type A and type B, parainfluenza viruses types 1, 2, 3 and 4 and by respiratory syncytial virus (RSV).
Despite their impact on the health system, they are socially accepted as a lesser evil that does not cause a significant enough impact to implement health restrictions.
SARS-CoV-2 has not yet met the conditions that could make it a seasonal coronavirus. As the entire world population has developed some type of specific immunity, it is possible that it becomes part of this group of common respiratory viruses, adapting and adapting in a process of limited damage.
It is too early to say how long it would take to reach this world immunization scenario. It would help if we facilitate the immunization of those countries with the most difficulties in accessing vaccines. Successive vaccine boosters in the form of booster doses, although they may reduce the incidence of susceptible variants to current vaccines, may lose efficacy to contain new variants.
Next-generation antivirals and vaccines
Looking to the future, if we wanted to aspire to end the virus, a new generation of vaccines would be necessary to improve long-term immunization, in addition to being more effective in preventing infection, contagion and improving protection against to new variants. This could be achieved by including more conserved proteins from the virus.
Meanwhile, other tools will allow us to better deal with the virus. Among them, the update of current vaccine formulations, the development and combination of recently appeared antivirals, as well as the improvement of treatments to prevent the death of people with severe and persistent covid-19.
Despite the risk that will continue to exist around covid-19, it is possible that sooner or later we all pass the infection and that the virus causes less damage to our daily lives.
Estanislao Nistal Villán, Virologist and Professor of Microbiology at the Faculty of Pharmacy, CEU San Pablo University
This article was originally published on The Conversation. Read the original.