Explained: Why do COVID19 vaccines cause side effects in some people

Many who have been vaccinated against COVID19 have reported a range of symptoms from fever and nausea to weakness and an upset stomach. Is it okay to have such side effects? What precautions must one follow while getting the jab? Read on to know more.

Gaon Connection
| Updated: June 14th, 2021

It is vital for a person to have a balanced and nutritious diet so as to lessen the usual side-effects of the COVID19 vaccine.

Symptoms such as  fever, headache, an upset stomach, weakness and nausea have been widely reported from some people who have been vaccinated against the COVID19 virus.

However,  many recipients of the COVID19 vaccine, be it Covishield or Covaxin, have not experienced  any side effects after getting the jab. Does it suggest the vaccine is not effective?

To understand this, we need to broadly understand the functioning of the immune system of our bodies.

How does the immune system work?

Our immune system is like a standing army that defends us against any pathogen that finds its way inside our bodies. The defence mechanism comprises  two processes — defence by White Blood Cells (WBCs) and production of antibodies.

Explained: What is the ‘delta’ variant of COVID19? Why is it dangerous? Can Covishield, Covaxin offer protection?

Mild-to-moderate side effects, like a low-grade fever or muscle aches, are normal and not a cause for concern.

The invasive attack could be by viruses, bacteria, fungi, a protozoa or any other microbe. The first responders to such an attack are the foot soldiers of the immune system — WBCs . They rush to the site of infection and try to fight the hordes of micro-organisms  that have entered the body. During their struggle to combat the pathogens, the body temperature increases and there is a general inflammation. 

Explained: What is the third wave of COVID19? Will it hit India? Are kids at greater risk?

This could be localised (redness,  soreness, and increased temperature in a certain part of the body) or manifest in the form of fever, with fatigue and chills. 

However, these WBCs cannot always contain the infection, and that is when a more specialised unit of our immune system —  ‘the antibodies’ —  arrive as reinforcements.  The purpose of the COVID19  vaccine is to ensure the production of these antibodies because they will be ready to withstand the attack in the event of an attack by the Sars-Cov-2 virus. 

Why is it okay to have mild side effects from COVID19 vaccines?

In its explanatory article on COVID19 vaccines, the World Health Organization (WHO) states that vaccines are designed to give you immunity without the dangers of getting the disease.

Explained: Why Covaxin is not approved by WHO? Why USFDA rejected its emergency use? Will it affect international travel?

“It’s common to experience some mild-to-moderate side effects when receiving vaccinations. This is because your immune system is instructing your body to react in certain ways: it increases blood flow so more immune cells can circulate, and it raises your body temperature in order to kill the virus,” the WHO has stated.

It noted that mild-to-moderate side effects, like a low-grade fever or muscle aches, are normal and not a cause for concern.

Our immune system is like a standing army that defends us against any pathogen that finds its way inside our bodies.

The organisation highlights that these are actually signs that the body’s immune system is responding to the vaccine, specifically the antigen (a substance that triggers an immune response), and is preparing itself to fight the virus. These side effects settle down after a few days.

“Experiencing no side effects doesn’t mean the vaccine is ineffective. It means everybody responds differently,” the WHO has said.

The action of WBCs gets lowered with age, which is why mostly it is young people who manifest these side-effects.

Also Read: FAQs about COVID19 vaccination

Precautions to follow while getting vaccinated against COVID19

It is vital for a person to have a balanced and nutritious diet so as to lessen the usual side-effects of the COVID19 vaccine. Experts have stated that a sufficient amount of protein in diets can lessen the usual side-effects of vaccines, known as ‘vaccine stress’.

Apart from this, the WHO advised that upon receiving the vaccine, a  person should be requested to stay for 15–30 minutes at the vaccination centre. “…So health workers are available in case of any immediate reactions. Individuals should alert their local health providers following vaccination if they experience any unexpected side effects or other health events – such as side effects lasting more than three days,” the WHO has stated.

“Less common side effects reported for some COVID19 vaccines have included severe allergic reactions such as anaphylaxis; however, this reaction is extremely rare,” it added.

Explained: Why fungal infections are on the rise amidst COVID19