December 30, 2020 6 min read
This story originally appeared on The Conversation
We live in an uncertain time, but “it is not up to us to decide what time to live, we can only choose what to do with the time that has been given to us”, as a wise man from Middle Earth said.
A century after the Spanish flu, we are better prepared in the face of a pandemic, but we have not been able to prevent thousands of deaths. We are facing a constant increase in infections that threatens to collapse our health system and facing an economy in recession.
It would seem sensible to identify those fortunate enough who are no longer at risk of being infected and also to grant them a “covid passport.” We may also grant them certain privileges, facilitate their mobility, or allow them to perform jobs with a higher risk of exposure to the virus.
This is how James Cleverly , the British Foreign Minister, put it: with this type of passport “we want to unlock people’s lives, unlock the economy, make sure we protect lives and protect livelihoods.”
But these words were qualified by the Secretary of Health, Matt Hancock, who has denied that such an “immunity passport” will exist in the United Kingdom.
The immunity passport
In Spain, the president of the Community of Madrid, Isabel Díaz Ayuso, has also defended the “covid passport” as a path to the desired “normality”. This passport, according to his words “informative”, associated with the virtual health card , would allow a person to justify their need to travel by showing a negative PCR on their mobile.
Given that a PCR can give false negatives, how often would we have to repeat it (at a cost of about 80 euros) to be sure that we really cannot infect? Also, when can we say that a person is immune to the coronavirus? And how can we say that it cannot continue to infect?
Until vaccination against covid-19 is implemented, the only way to be immune is to have suffered and overcome the infection. If our immune system has been able to eliminate the virus, we will probably be immune in case it decides to fight back. Or, at least, it has been so far.
Immunity after infection
If we have overcome the infection, our innate and adaptive immunity, the one that evolves depending on the pathogen and that depends on our lymphocytes, has worked, in the case of the coronavirus.
The vaccines “simulate” an infection, instructing the lymphocytes on what to recognize and what to do after they have recognized it. The three main vaccines against covid-19 would prevent us from suffering from the disease associated with the virus. They would instruct B lymphocytes to make antibodies that attack the virus when it is on the outside of our cells. It is the so-called humoral immunity.
However, can we confirm that we are immune to the virus after having overcome an infection or having been vaccinated? It is important to know that a part of the B lymphocytes do not disappear with the virus or the vaccine, but are transformed into “memory” cells.
These “remind” us which virus has infected us and prevent it from doing so again. As time passes, if we do not have a new contact with the virus, we can lose this humoral memory. In this way, our antibodies could be undetectable in the tests.
Are we then unprotected?
It may happen that we have been vaccinated or we have overcome an infection and our antibody test is negative. Viruses multiply inside cells and to detect and eliminate infected cells we have “killer” T lymphocytes or CD8, which can remain as memory cells patrolling and waiting to meet again with cells infected by the virus.
Currently, there is no rapid test that detects this cellular immunity. Therefore, a negative result in an antibody test does not necessarily imply that we are unprotected against COVID-19.
Immunity and contagion
It is common to hear that if a person is immune they cannot infect us. However, having been infected or vaccinated and testing positive for antibodies does not guarantee that we are immune to infection.
In different countries, including Spain, reinfections have been confirmed in patients who had overcome the disease. Fortunately they are exceptions, but nobody wants to be that exception.
On the other hand, not all antibodies are effective. Only if we are lucky will our B lymphocytes have made antibodies capable of neutralizing the “keys” that the virus uses to enter our cells.
Likewise, a vaccinated person may be protected against the pathology of covid-19, but that does not mean that they cannot transmit the virus. We still don’t know who will be faster, the virus multiplying or the immune system eliminating it.
The ethics of the immunity passport
Until the entire population is vaccinated in a generalized way and free antibody or PCR and antigen tests are established, establishing a “covid passport” could be discriminatory.
All this assuming that the coronavirus mutations do not reduce the protection that vaccines or a previous infection confer on us. Therefore, a “covid immunity passport”, even giving positive in an antibody test and even being only informative, can be problematic, giving a false sense of security that could put at risk both its carrier and the people of its environment.
This article is republished from The Conversation under a Creative Commons license. Read the original article .