Buddhist monks are injected with the Sinovac Covid-19 coronavirus vaccine at the Priest Hospital in Bangkok on May 18, 2021. (AFP / Jack Taylor)

Posts mislead on why some people experience Covid-19 vaccine side effects

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Multiple posts shared repeatedly on Facebook claim that people who do not experience side effects after receiving a Covid-19 jab are “unhealthy”. The claim is misleading: a person's reaction to receiving the vaccine does not necessarily reflect how healthy they are, a health expert told AFP. The World Health Organization (WHO) says experiencing no side effects does not mean the vaccine is "ineffective" and everyone "responds differently" to the vaccine. 

The claim was shared here on Facebook on June 10, 2021.

“One common misunderstanding is that having no side effects from the vaccine is a good thing, but this is not true,” the Thai-language text reads.

“If you are vaccinated and you have a fever, it means that you have already built up your immune system against the [virus], that’s why you have some symptoms, showing that you are strong.

"But if you don’t have any side effects, it means that you don’t really have an immune response. That’s why your body doesn’t show anything in response to the unknown matter that has entered your body. This means that you are not healthy.”

As of June 22, Thailand had administered more than 7.9 million doses of AstraZeneca's Covid-19 vaccine and Sinovac’s CoronaVac vaccine.

Similar claims have also been shared on Facebook here, here, and here.

The claim is misleading, according to a health expert.

Dr. Kajornsak Kaewcharat, Thailand’s Department of Disease Control deputy director-general, said the severity of Covid-19 vaccine side effects someone experiences does not necessarily indicate how healthy they are.

“Everyone responds to an unknown matter differently, which results in differences of side effects occurring after they receive Covid-19 vaccination,” he told AFP on June 22.

“Some people are allergic to a certain food, while some people are not. The same goes for vaccines.

"If you compare two healthy people of the same sex and age, their bodies will react to the vaccines through different inflammatory processes.”

'Everybody responds differently'

If someone who receives a Covid-19 vaccine does not experience side effects, it does not indicate the vaccine was "ineffective", according to the World Health Organization (WHO).

"Common and mild or moderate side effects are a good thing: they show us that the vaccine is working. Experiencing no side effects doesn’t mean the vaccine is ineffective. It means everybody responds differently," it states here.

In countries where vaccines have been administered, people are regarded as fully vaccinated two weeks after their second vaccination, regardless of whether they experience side effects.

According to the US Centers for Disease Control and Prevention (CDC), a person is considered fully vaccinated two weeks after getting their second shot of most Covid-19 vaccines.

For Johnson & Johnson's Janssen vaccine, only one shot is required, it says.

Covid-19 vaccine side effects -- including arm pain and fever -- are “normal signs that your body is building protection”, but some people may experience “no side effects”, the CDC's website states.