Coronavirus vaccine: Why do some people get side-effects and some don't?

Coronavirus vaccines have been proven to be well-effective against coronavirus and can even potentially curb severity rates. Of course, side-effects are something that accompanies vaccines- some usual, some unusual and some downright severe enough to prompt action. However, with more and more people getting vaccinated, it has become evident that the side-effects aren't uniform for everyone. Some get the typical ones, some suffer from the greater intensity of it, while some escape unscathed- and have no side-effects. But why does this disparity happen? We explain...

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Side-effects refer to the reactions that take place when the body is exposed to an external antigen. The way our system reacts to the same shows up in the form of side-effects.

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Upon exposure, our immune system kicks into action. While the first part sends white blood cells and defensive antibodies to fight the pathogen, it also prompts inflammatory responses against the infection- making a person experience symptoms like fever, fatigue, muscle soreness, pain, chills etc. These are also what many refer to as the common side-effects and reactions expected with vaccines.

Some unusual side-effects or inflammatory reactions may also occur, depending on how a person reacts to the vaccine.

While side-effects can be experienced generally, it is common knowledge that no two bodies react the same way to the same vaccine. It can also happen that different vaccines showcase different responses. For example, it has now been shown that Covaxin tends to dole out 'fewer' inflammatory reactions in comparison to Covishield.

Therefore, whether or not a person reacts to a vaccine, or has the same reactions as someone else depends on the way the individual system reacts to the antigen in the vaccine. Clinical trials from Pfizer's mRNA vaccine study also observed that over 50% of people reported suffering from no side-effects after getting the jab, and were still protected.

Apart from this, factors like age, gender, pre-existing immunity, health conditions, use of anti-inflammatory medicines may also impact the side-effects you get. This is one of the reasons why younger people report more side-effects than older people. Newer research also indicates that the time of the day a person gets jabbed may also affect inflammatory reactions.

Increasing data has shown that the side-effects and vaccines tend to work differently across genders. Women, more than men, tend to experience harsher, and more intense side-effects from the vaccine doses, in comparison to their counterparts. This could also lead to a difference in reporting of symptoms, between men and women.

One of the reasons why women tend to experience more side-effects could be because of the way hormones interact with the immune-system make-up. Heightened estrogen levels may lead to more inflammatory reactions, and increase the duration of the side-effects as well. Hormonal interference may also make women experience some different side-effects, such as swollen lymph nodes under the arms as well. In comparison to this, men have not been shown to report any distinct side-effects with vaccines.

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Lastly, there looms a question- what happens if you don't get any side-effects? Does it mean that your vaccine is still working?

The answer, according to many experts, is that no-show side-effects shouldn't be a reason right now to get concerned. Every vaccine works in the same way and not getting any side-effects, or the ones which may be barely noticeable may only mean that your body is reacting to it differently.

In no way does it imply that the immune system has not accepted the vaccine, or the vaccine may not be working. It can also happen that a person who doesn't develop side-effects after the first shot, gets side-effects with the second dose. Or, it can happen that reactions do not show up altogether.

As long as sufficient antibodies are produced, and you follow utmost COVID appropriate behaviour, there's nothing to be worried about.