Here we are, it seems time 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 reflections. With the Italian curve now finally flattening out, the acceleration of studies anti-viral and on vaccines against SARS-CoV-2 and the launch of antibody tests for screening of 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 fortune-tellers, and all predictions may be more or less far from the truth. But virologists and public health experts generally agree on one fact: immunity is the key. Whether it is obtained through safe and effective vaccinations, or through the achievement of the much-loved “herd immunity”. Well, maybe not that expensive. Rather. Especially to Boris Johnson. And here we come to the topic to overlook: the Immuni app, which is about to enter 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 results that could quickly diverge into many possible futures. It is also why estimates of how long it will take Covid-19 to disappear (if it does) vary enormously. Someone says he has already disappeared (Alberto Zangrillo, director of the intensive care of the 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, come to think of it, isn't just the key factor in determining when everything is really over. There are also other important questions: can you get infected again with the same virus yes or no? Will vaccines really work yes or no, and will they be worth it forever? If not, for how long? Can positive antibody tests, showing 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 the 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, metaphorically, is a whole "army" of special forces units: cell scouts, killer cell killers, antibody troops, and intelligence agents who log each encounter with a new enemy. When our body is attacked by a new enemy (virus, bacteria or even a cancer) surveillance kicks in.
Normally, a type of peach-like-looking white blood cell called T cell wanders in our bloodstream. When it detects fragments of "alien" proteins (perhaps due to the effect of a virus that replicates itself) it alerts other components of the immune system to organize the Resistance. The Resistance troops are armed to the teeth, and also have tricks 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. The cytokines know their stuff, and destroy the invader.
But my favorite weapon is the B cell, a bulbous, sympathetic-looking white blood cell. There cell B it's a bit like James Bond's Q sector: it creates new weapons, "custom" antibodies, each Y-shaped with two powerful arms, arranging them to specifically attack a new viral enemy. The antibodies go to the "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 too 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, generally they will trigger a fever. In a small part of the cases, unfortunately in that of Covid-19, they seem to go crazy and turn into a process called "cytokine storm" that ends up damaging the host tissue. These excessive immune reactions are perhaps the reason why some young people suffering from Covid-19 have also died without previous pathologies.
For the luckiest patients, fortunately the vast majority, the immune system remains lucid. The antibodies generally hang around for a while to "patrol" any new attacks, although their residence time depends on the particular virus. And in the case of Covid-19 we do not know it: it could even be short. In the meantime, however, the immune system records the war just ended using memory cells (also these 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
Seeing how wonderful is 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 of the past, at least to me, a profane and humble popularizer, 3 possible scenarios come to mind on the "death of Covid- 19 ".
1 - The best 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. An immune response similar to what our body has against varicella-zoster, the chickenpox virus, may occur. Infection with this virus, or vaccination against it and many other infectious childhood diseases, can be uncomfortable, but they are one. Direct infection or vaccination can cause the immune system to remember the virus FOR LIFE. You can't take it back anymore (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 as with chickenpox, those who have had the virus and have 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, in your opinion. 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's early: some studies show that not all people infected with the Covid-19 virus are able to 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 recovered from Covid-19, we will not recover them 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 could get infected, either after the initial infection or after a vaccine. The reason is that for some viruses the antibodies may thin after a while, as if they "atrophy" from lack of activity. A study on the OG SARS virus who terrorized much of East Asia in 2003, for example, found that the antibody levels dropped dramatically three years after the initial infection. However, it must be said, indeed repeating 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 encounter the virus again, they would quickly trigger a response. immune. I mean, we would 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 rapidly and dramatically enough to overcome our immune systems, our bodies will no longer be able to detect it quickly. 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 flu virus transforms 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 super-speed of the flu. Preliminary studies have found that SARS-CoV-2 appears changing at a much slower pace 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 nobody knows. However, unless SARS-CoV-2 is a total freak of nature, it will fall into one of the three categories I have exposed to you. And that's something, isn't it? After all, uncertainty is the scariest thing of all.
Oh yeah. Immune. I almost forgot. Ok. the next question, thanks :)