[ad_1]
By 2021, hundreds of millions of people will be vaccinated against SARS-CoV-2. The success of this COVID-19 vaccination campaign will depend heavily on public confidence that the vaccines are not only effective, but also safe. To build that trust, the medical and scientific communities have a responsibility to engage in difficult discussions with the public about the significant fraction of people who will experience temporary side effects from these vaccines.
I’m an immunologist who studies the fundamentals of immune responses to vaccination, so part of that responsibility falls on me.
Simply put, getting these vaccines will likely make a lot of people feel crap for a few days. That’s probably a good thing, and it’s a much better prospect than long-term illness or death.
The ‘dirty little secret’ of immunology
In 1989, immunologist Charles Janeway published an article summarizing the state of the field of immunology. Until then, immunologists had admitted that immune responses were triggered upon encountering something foreign – bacteria, viruses, and parasites – that was “non-self.”
Janeway suspected there was more to the story and exposed what he called “the dirty little secret of the immunologist”: Your immune system doesn’t just react to foreign things. He responds to foreign things that he perceives as dangerous.
Now, 30 years later, immunologists know that your immune system uses a complex set of sensors to understand not only whether something is foreign or not, but also what kind of threat, if any, a microbe might pose. It can tell the difference between viruses – like SARS-CoV-2 – and parasites, like tapeworms, and activate the specialized arms of your immune system to deal with those specific threats accordingly. It can even monitor the level of tissue damage caused by an invader and boost your immune response accordingly.
Detecting the type of threat posed by a microbe and the level of intensity of that threat allows your immune system to pick the right set of responses, use them accurately, and avoid the very real danger of immune overreaction.
Vaccine adjuvants bring the danger we need
Vaccines work by introducing a safe version of a pathogen into a patient’s immune system. Your immune system remembers its past encounters and reacts more effectively if it sees the same pathogen again. However, it only generates memory if the vaccine contains enough danger signals to trigger a strong immune response.
As a result, your immune system’s need to detect danger before reacting is both extremely important (imagine if it has started attacking the thousands of species of friendly bacteria in your gut!) And very problematic. The danger requirement means that your immune system is programmed not to respond unless a clear threat is identified. It also means that if I develop a vaccine, I have to convince your immune system that the vaccine itself is a threat worth taking seriously.
This can be accomplished in several ways. One is to inject a weakened – what immunologists call attenuated – or even killed version of a pathogen. This approach has the advantage of appearing almost identical to the “real” pathogen, triggering many of the same danger signals and often resulting in strong long-term immunity, as seen in polio vaccination. It can also be risky – if you haven’t weakened the pathogen enough and deployed the vaccine too quickly, there is a possibility of unintentionally infecting large numbers of vaccinees. In addition to this unacceptable human cost, the resulting loss of confidence in the vaccines could lead to further suffering as fewer people take other, safer vaccines.
A safer approach is to use individual components of the pathogen that are harmless in themselves but able to train your immune system to recognize reality. However, these pieces of the pathogen often do not contain the danger signals necessary to stimulate a strong memory response. As a result, they must be supplemented by synthetic danger signals, which immunologists call “adjuvants”.
Adjuvants are safe, but designed to ignite
To make vaccines more effective, entire laboratories have been devoted to testing and developing new adjuvants. All are designed with the same basic goal: to activate the immune system in a way that maximizes the effectiveness and longevity of the response. In doing so, we maximize the number of people who will benefit from the vaccine and the duration of protection for those people.
To do this, we take advantage of the same sensors your immune system uses to detect damage during an active infection. This means that although they stimulate an effective immune response, they will do so by producing temporary inflammatory effects. At the cellular level, the vaccine triggers inflammation at the injection site. The blood vessels in the area become a little more “leaky” to help recruit immune cells into the muscle tissue, causing the area to turn red and swell. All of this triggers a full-blown immune response in a lymph node somewhere nearby that will unfold over the weeks.
In terms of symptoms, this can lead to redness and swelling at the injection site, stiffness and pain in the muscle, tenderness and swelling of the local lymph nodes and, if the vaccine is strong enough, even fever. (and that’s usually associated with feeling like shit.).
It’s the balance between vaccine design – maximizing protection and benefits while minimizing their uncomfortable but necessary side effects. That’s not to say serious side effects don’t happen – they do – but they are extremely rare. Two of the most discussed serious side effects, anaphalaxia (a severe allergic reaction) and Guillain-Barré syndrome (nerve damage due to inflammation), occur at a frequency of less than 1 in 500,000 doses.
Vaccination against SARS-CoV-2
Early data suggests that the developing SARS-CoV-2 mRNA vaccines are highly effective – over 90%. This means that they are able to stimulate robust immune responses, with sufficient danger signaling, in more than nine out of 10 patients. This is a high number under all circumstances, and suggests that these vaccines are potent.
So let’s be clear here. You should expect to experience pain at the injection site the day after your vaccination. You should expect some redness and swelling, and you might even expect to feel generally exhausted for a day or two after vaccination. All of these things are normal, anticipated and even intentional.
Although the data is not final, more than 2% of Moderna vaccinees experienced what they described as serious temporary side effects such as fatigue and headaches. The percentage of people who experience side effects will be higher. These are signs the vaccine is doing what it was designed to do: train your immune system to react against something it might otherwise ignore so that you are protected later. This does not mean that the vaccine gave you COVID-19.
It all boils down to this: In the coming months, you will have a simple choice to protect yourself, your loved ones and your community from a highly communicable and fatal disease that has long-term health consequences for a significant number. otherwise healthy people. It can cost you a few days of unease. Please choose wisely.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
[ad_2]
Source link