The SARS-CoV-2 vaccine has side effects-that’s a good thing

Matthew Woodruff
Emory University

Temporary side effects of the vaccine are a normal sign of the progression of the immune response.

Vaccines work by training the immune system to recognize and remember pathogens in a safe way.

Possible side effects of the COVID-19 vaccine include redness and swelling at the injection site, muscle stiffness and pain.

Powerful vaccines can even cause fever. It does not mean that the vaccine has given you COVID-19.

By 2021, hundreds of millions of people will be vaccinated against SARS-CoV-2. The success of the COVID-19 vaccination campaign relies heavily on public confidence that the vaccine is not only effective but also safe. To build that trust, the medical and scientific communities are responsible for having difficult discussions with the general public about a significant portion of those who experience the temporary side effects of these vaccines.

I am an immunologist studying the basics of the immune response to vaccination, so part of that responsibility lies with me.

Simply put, vaccination with these vaccines will make many feel cheesy for a few days. That’s probably a good thing, and it’s a much better prospect than long-term illness or death.

Immunology’Dirty

A little secret “

In 1989, immunologist Charles Janeway published an article summarizing the current state of the field of immunology. By that time, immunologists had accepted that the immune response would begin when they encountered a foreign body (bacteria, virus, parasite) that was “non-self.”

Janeway suspected that there was much more to the story, and famously explained what he called “the dirty little secret of immunologists.” Your immune system does more than just react to foreign substances. It reacts to foreign objects that you feel are dangerous.

Thirty years later, immunologists now understand that the immune system uses a complex set of sensors to understand not only whether something is foreign, but also the types of threats that microorganisms can pose. I know It can identify the difference between viruses like SARS-CoV-2 and parasites like tapeworms and accordingly activate special arms of the immune system to address those particular threats. I can do it. You can also monitor the level of tissue damage caused by an intruder and increase your immune response accordingly.

By sensing the type of threat posed by microorganisms and the level of intensity of that threat, the immune system selects the appropriate set of responses and uses them accurately to create a very realistic risk of immune overreaction. Can be avoided.

Vaccine adjuvant

Necessary danger

Vaccines work by introducing a safe version of the pathogen into the patient’s immune system. Your immune system remembers past encounters and reacts more efficiently if you look at the same pathogen again. However, it produces memory only if the vaccine is packed with enough warning signals to initiate a reliable immune response.

As a result, the need to detect danger before the immune system reacts is immediately very important (imagine when it begins to attack thousands of friendly bacteria in the gut!). , Very problematic. The risk requirement means that the immune system is programmed to not respond unless a clear threat is identified. It also means that if I’m developing a vaccine, I have to convince your immune system that the vaccine itself is a threat worth taking seriously.

This can be achieved in several ways. One is to inject a weakened version (what immunologists call attenuated) or a killed version of the pathogen. This approach has the advantage of appearing to look much like a “real” pathogen, causing many of the same warning signals, often resulting in strong, long-term immunity, as seen in polio vaccination. There are also risks. If the pathogen is not sufficiently weakened and the vaccine is deployed too quickly, it can unintentionally infect a large number of vaccinated people. In addition to this unacceptable human cost, the loss of confidence in the vaccine can lead to further distress as fewer people take other safer vaccines.

A safer approach is to use the individual components of the pathogen. It is harmless in itself, but it can train the immune system to recognize the real thing. However, these pathogens often do not contain the warning signals needed to stimulate a strong memory response. As a result, it needs to be supplemented with a synthetic danger signal that immunologists call “adjuvants.”

Adjuvants are safe but designed to cause inflammation

To make the vaccine more effective, the entire lab has been dedicated to testing and developing new adjuvants. Everything is designed for the same basic purpose-working the immune system in a way that maximizes response effectiveness and longevity. Doing so maximizes the number of people who will benefit from the vaccine and the length of time they are protected.

To do this, it utilizes the same sensors that the immune system uses to detect damage to active infections. That is, it stimulates an effective immune response while producing a temporary inflammatory effect. At the cellular level, the vaccine causes inflammation at the injection site. Blood vessels in that area become a little more “leaky,” helping to mobilize immune cells into muscle tissue and causing the area to swell red. All of this initiates a full-blown immune response in nearby lymph nodes and progresses over several weeks.

In terms of symptoms, this is associated with redness and swelling at the injection site, muscle stiffness and pain, tenderness and swelling of local lymph nodes, and fever (and generally crappy feeling) if the vaccine is strong enough. May bring).

This is the balance of vaccine design-maximizing protection and benefits while minimizing unpleasant but necessary side effects. I’m not saying that serious side effects don’t occur-it does-but they are very rare. Two of the most discussed serious side effects, anaphylaxis (severe allergic reaction) and Guillain-Barré syndrome (nerve damage due to inflammation), occur less than once in 500,000 times.

Vaccination against

SARS-CoV-2

Early data suggest that the mRNA vaccine under development for SARS-CoV-2 is very effective-over 90%. This means that more than 9 out of 10 patients can stimulate a strong immune response with sufficient warning signals. This is a high number in all situations, suggesting that these vaccines are powerful.

Let’s clarify here. You should expect to feel pain at the injection site the day after you are vaccinated. Some redness and swelling are expected. You may also feel generally debilitated 1-2 days after vaccination. These are all normal, expected and intended.

Although data are uncertain, more than 2% of Moderna vaccinated people experienced what they classified as severe temporary side effects such as fatigue and headaches. The percentage of people who experience side effects is high. These show that the vaccine is working as designed. Train your immune system to react to things that might otherwise be ignored and to be protected later. It does not mean that the vaccine has given you COVID-19.

It all comes down to this: At some point in the coming months, you will be given an easy choice to protect yourself, your loved ones, and your community from highly contagious and deadly illnesses. I will. Of otherwise healthy people. It may take several days before you feel sick.

Choose wisely.

Conversations are an independent, non-profit source of news, analysis and commentary from academic professionals.