Covid: the 4 phases your body experiences when you get the vaccine (and how quickly side effects could occur)

“We don’t know the long-term side effects of covid vaccines.” It is a message that is still common to see shared on the internet.

But in reality, one year is considered a “long run” when it comes to vaccine safety.

It’s been more than 14 months since the first doses began to be administered and more than 12 since vaccines began to be distributed under the Covax scheme, with which the World Health Organization (WHO) seeks an equitable distribution of them among the least developed countries.

Scientists say that this is more than enough time for side effects to appear.

And it is that, although vaccines against covid are relatively new, the processes that are triggered in your body are not so new.

Understand how they stimulate immune system it can help us know how quickly we can expect to have negative reactions.

Next, we will tell you what are the phases that your body experiences after receiving the covid vaccine and the time periods that you must take into account.

1. After 15 minutes

A small group of people will have a allergic reaction to the inactive ingredients of the vaccine, and this will occur within 15 minutes of receipt.

For everyone else, the side effects are the result of the body reacting to the vaccine itself, or to the antibodies it makes your body produce.

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2. Innate phase: after a few hours

The innate phasein which the body reacts to the vaccine itself, begins almost immediately.

Your body recognizes an invader and attacks it with immune cells, the weapons it would use against any virus or bacteria.

We know that any reaction associated with this phase will occur in a matter of hours or in a couple of daysincluding the most common side effects: arm pain, fever, and other mild symptoms similar to those of the flu.

A much more unusual side effect that has been linked to Pfizer and Moderna’s mRNA vaccines, myocarditis, or inflammation of the heart, would also occur in this phase.

Although the exact cause of myocarditis is not fully understood, we know that the inflammation it is one of the body’s responses to infection or injury.

Vaccine-induced myocarditis is usually mild and improves on its own or with basic anti-inflammatory medications such as ibuprofen.

3. Adaptive phase: after 10 days

The innate phase initiates the second part of your immune response: the adaptive phasein which your body begins to produce cells that are specifically designed to fight the target virus.

This phase begins after about 10 days, so it takes the same time for the vaccine to start having any effect to protect you against covid.

Your body pumps new immune cellsin a response that peaks after about two weeks and fades after about 28 days.

A very bad side effect unusual but serious AstraZeneca vaccine-related infection, a specific type of blood clot, occurs during this phase and is related to antibodies produced by the immune system in response to the vaccine.

That’s why most of these rare blood clots have occurred within four weeks of vaccination.

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4. At 28 days

Once the adaptation phase wears off, after about a month, there are memory cells left in your body that give you protection for months or years after the initial exposure, but no new response occurs, explains Dr. Victoria Male, a reproductive immunologist in London.

So, says Male, if you haven’t had a reaction after the first few months, it’s very improbable that anything that happens after that is caused by the vaccine.

There’s never a 100% guarantee with anything in medicine, so we can’t say it’s completely impossible for it to happen, but scientists can’t remember a single vaccine in history where new side effects emerged more than six months later.

“The history of vaccines assures us that most side effects occur within hours of receiving the vaccine, and rare side effects occur within days or weeks,” explains Jeffrey Mphahlele, a leading South African infectious disease researcher.

Will we identify any new effects?

From our understanding of how the immune system works garnered over centuries of knowledge, we know that it is very unlikely that a person who did not have a reaction to the vaccine in the first few months will have new side effects later.

But is it possible that side effects that have already occurred will go unnoticed and may come to light in years to come?

Countries around the world have implemented systems to monitor for side effects and share that information with each other.

These systems were able to detect both the blood clots and myocarditis we already mentioned, despite being extremely rare, with only a handful of cases per million doses.

While milder symptoms such as arm pain or increased temperature are likely to be significantly underreported, the most serious side effects are carefully recordedsays Dr. Male.

In addition, there are other important vaccine safety studies that do not rely on people reporting their own experiences, such as the Vaccine Safety Datalink (the Vaccine Safety Data Link project), in the United States.

Since we expect side effects to come on relatively quickly, perhaps a more relevant thing to consider, rather than how long it’s been, is how many doses have been givensuggests Dr. Chandrakant Lahariya, an epidemiologist in Delhi, India.

“Billions of doses have been given, so any side effects that haven’t been seen yet would be more unusual than one in a billion,” he said.

However, medical systems around the world are still looking for side effects, Lahariya adds.

In fact, while all vaccines have completed the expected three phases of trials that are usually conducted before being offered to the general public, they are still being carefully monitored. until at least 2023to make sure even the rarest events are caught.

Finally, it should be remembered that safety in medicine consists of balance risks and benefits.

All the evidence suggests that the overall risks of contracting covid are many times higher than any risk from the vaccine.