Here we are, it seems the time has come to adopt (for those who want) the famous tracking app that has attracted the attention of the media in recent months. Will it help? Let's do some reflection. With the Italian curve now finally flattening, the acceleration of studies anti-viral and on vaccines against SARS-CoV-2 and the launch of antibody tests for screening those who may have already had the infection, it seems that science is rapidly positioning itself to checkmate Covid-19. How will we remember the pandemic in a few years?
It is a matter for soothsayers, and all predictions may be more or less far from the truth. But virologists and public health experts generally agree on one thing: immunity is the key. Whether it is obtained through safe and effective vaccinations, or through the achievement of the much cherished "herd immunity". Well, maybe not that expensive. On the contrary. Especially to Boris Johnson. And here we come to the matter to be overlooked: the Immuni app, which is about to make its entry into the lives of many Italians.
We cannot speak of Immune without first speaking of immunity
Like most processes in biology, immunity to SARS-CoV-2 is complex and mysterious, with outcomes that could rapidly diverge across many possible futures. It's also why estimates of how long it will take for Covid-19 to go away (if at all) vary wildly. Some say he has already disappeared (Alberto Zangrillo, director of the intensive care unit at San Raffaele in Milan, with all its load of controversy). Others speculate months. Other years. For some it will never go away, but it will become endemic.
Immunity, when you think about it, isn't just the key factor in determining when it's all really over. There are also other important questions: can one get infected again with the same virus yes or no? Will vaccines really work, yes or no, and will they be valid forever? If not, for how long? Can positive antibody tests, which show that you have been previously infected, have the value of an “immune passport” yes or no?
Here's how immunity works and a look at possible futures in our war against Covid-19.
Our immune system
Let's start with this: antibodies have gotten all the limelight, but they are only part of our immune response.
The immune system, on a metaphorical level, is an entire “army” of special forces units: cell scouts, killer cell killers, antibody troops and intelligence agents who record every encounter with a new enemy. When our body is attacked by a new enemy (virus, bacteria or even cancer) surveillance goes into action.
Normally, a type of white blood cell called a peach in appearance T cell it wanders into our bloodstream. When it detects fragments of "alien" proteins (perhaps due to a virus that replicates itself) it alerts other components of the immune system to organize resistance. The Resistance troops are armed to the teeth, and they also have aces up their sleeves: for example macrophages, the "tanks" of the immune system, can literally swallow some viruses and digest their material. In some cases, killer cells are “enlisted” (yes, they are called just like that) that launch streams of “protein missiles” called cytokines. Cytokines know what they're doing, and destroy the invader.
My favorite weapon, however, is the B cell, a bulbous and friendly-looking white blood cell. There cell B it's a bit like James Bond's Q sector: it creates new weapons, "personalized" antibodies, each Y-shaped with two powerful arms, organizing them to specifically attack a new viral enemy. The antibodies enter into a "deadly" embrace with the virus and neutralize it. And because they are very specific for a virus, testing for specific antibodies to SARS-CoV-2 is generally a sign that you have been infected with the virus.
Like any self-respecting war, this one is not painless for anyone, not even for the human host, and can also have unwanted side effects or unexpected outcomes. These immune responses are not completely benign, they will generally trigger a fever. In a small part of cases, unfortunately in that of Covid-19, they seem to go crazy and transform into a process called "cytokine storm" which ends up damaging the host tissue. These excessive immune reactions are perhaps the reason why some young Covid-19 patients without previous pathologies have also died.
For the luckiest patients, fortunately the vast majority, the immune system remains clear. Antibodies generally stick around for a while to “patrol” for any new attacks, although how long they stay depends on the particular virus. And in the case of Covid-19 we don't know: it could even be short. In the meantime, however, the immune system records the war that has just ended using memory cells (these too they really are called that!), the T lymphocytes. These cells remain in our body for longer than I fear: perhaps they forgive, but they certainly do not forget: and if the enemy returns they will prepare themselves much more quickly to counterattack.
Three potential outcomes
See how wonderful, our immune response? Now, putting together the functioning of our immune system with what we know about the virus at the moment and with what we know about other viruses in the past, at least to me, a layman and humble communicator, 3 possible scenarios come to mind regarding the "death of Covid- 19".
1 – The best case scenario
Notice everyone right away: if this scenario occurs, I offer a coffee to all readers of this post who will leave a comment with the code CAFFETTINO. There may be an immune response similar to the one our body has against varicella-zoster, the chickenpox virus. Infection with this virus, or vaccination against it and many other childhood infectious diseases, can be inconvenient, but they are one. Direct infection or vaccination can cause the immune system to remember the virus FOR LIFE. You can never take it back (except, but this is pure bad luck, in the form of a rather painful condition called “shingles”, but this shows how complicated the war on viruses is). In short, if it ends up like chickenpox, those who have had the virus and recovered will have immunity for life. We will get rid of Covid-19 forever.
Too good to be true? Already. And so I dared to offer coffee to everyone, according to you. Unfortunately, previous research on coronaviruses suggests that yes, we will likely have some immunity, but it may not last. WHAT DOES THE RESEARCH SAY? – As always, it is early: some studies show that not all people infected with the Covid-19 virus are capable of generate antibodies . A pre-press study who examined rhesus monkeys infected with SARS-CoV-2 found that two who had been reinfected 28 days after recovery were able to effectively fight the virus. Based on this very preliminary data, it appears that we will have at least temporary immunity, that is, once we recover from Covid-19, we will not recover immediately. Without further data, of course, it's still a theory. Which brings us to the second scenario.
2 – The intermediate scenario
We get immunity, but it doesn't last forever. We may become infected, either after the initial infection or after a vaccine. The reason is that for some viruses the antibodies can wear thin after a while, as if they were “atrophying” due to lack of activity. A study on the OG SARS virus that terrorized much of East Asia in 2003, for example, found that antibody levels dropped dramatically three years after the initial infection. However, it must be said, or rather repeat something said before: our immune system would still retain a memory of SARS-CoV-2, so if the memory T cells or the remaining antibodies encountered the virus again, they would quickly trigger a response immune. I mean, we'd get sick again, but it probably wouldn't be as bad as the first time.
3 – The worst case scenario
The seasonal battle of cat and mouse. If the virus mutates quickly and dramatically enough to overcome our immune systems, our bodies will no longer be able to quickly detect it. Our immune intelligence systems and the work of our “army” will once again have to fight a new enemy, albeit similar to the previous one. It's a frustrating scenario, but that's exactly what happens with the flu every year. The influenza virus mutates at an incredibly rapid rate, which means we are always one step behind and the virus becomes a seasonal nuisance. The good news is that not all viruses have the superspeed of the flu. Preliminary studies have found that SARS-CoV-2 appears changing at a much slower pace of influenza, and this may be, if confirmed by further studies, great news for the attachment power of vaccines.
In short, how does the Covid-19 pandemic end?
The inconvenient truth is that no one knows. However, unless SARS-CoV-2 is a total freak of nature, it will fall into one of the three categories I have laid out for you. And that's something, isn't it? After all, it is uncertainty that is the scariest thing of all.
And Immune?
Oh yeah. Immune. I almost forgot. Ok. the next question, thanks :)
