Why do some react more violently to corona vaccines than others?

You may have noticed: after vaccination with one of the corona vaccines, one is sick in bed with a high fever, while the other has at most a sore arm. How is that possible?

Unfortunately, there is no unequivocal answer to this. Because every person is different, and that also applies to the immune system. According to immunologist Marjolein van Egmond (Amsterdam UMC), it is impossible to predict how someone will react to the processes in their body that have been set in motion by the vaccine. “For example, it is not the case that healthy, fit people experience fewer side effects. Compare it with different family members who contract the same cold virus. One gets a runny nose, the other is flat for three days,” she says. the AD.

Second shot: more severe side effects

The fact that you react more strongly to the vaccines may, for example, have to do with which shot you received. Was it your first or second shot? And what type of vaccine did you get? According to the Lareb side effects center, more people experience side effects after the second injection of the mRNA vaccines from Pfizer/BioNTech, according to the package leaflet. “These side effects may also be more severe than with the first vaccination,” the center reports his website. Complaints such as fever are especially mentioned. The Moderna vaccine – also based on mRNA technology – is also known to cause more side effects with the second vaccination. Fortunately, these usually disappear after a few days.

Vaccinologist Anke Huckriede of the University Medical Center Groningen lays down RTL News shows that the more severe side effects after the second shot with an mRNA vaccine probably have to do with the immunity built up by the first shot. “We call this ‘acquired immunity’. The body responds to the new exposure by activating the previously built up immune cells.” According to Huckriede, this is only a hypothesis, which needs further investigation.

More intense reaction if you’ve already had corona

Another cause for your stronger reaction to the corona vaccine is that you have already been infected with the corona virus (unnoticed). The Health Council advises people who have already had covid-19 to get vaccinated once. That’s not for nothing. After all, if you have received two injections, you can suffer more from side effects and they can also be more severe. That also turned out recent research with participants who had received the Pfizer or Moderna vaccine. Of the two groups, the first group – which included participants who had previously been infected – experienced side effects as much as 89 percent. In the second group, with no previous infection, only 46 percent had side effects.

According to Ben van der Zeijst, professor emeritus of vaccine development, this is due to a ‘very high antibody response’, which is much more powerful than in other people. The antibody response is even ten to thirty times higher in people who have been previously infected. After one shot they are ‘super well protected’, says Van der Zeijst to RTL News. But then you have to know whether you have already had the virus among the members.

Do you also have a good question? Send us an email.