Fever, fatigue, furious headache: Here's why Pfizer's second jab is more painful

Since December 2020, the vaccination campaign has opened in England with COVID-19 vaccines. Among them: Pfizer/BioNTech, AstraZeneca, Moderna or Johnson & Johnson. Although the AstraZeneca vaccine has been strongly questioned due to some cases of thrombosis, the vaccination campaign is forging ahead swimmingly.

At this stage, 41,551,201 have already received their first dose and 71,343,859 are fully vaccinated. From a simple redness in the arm to full-blown fever, symptoms after vaccination are diverse and vary from person to person.

For some, the second dose of Pfizer's first licensed vaccine proved to be a real ordeal, but fortunately, not everyone is affected.

Pfizer's second reportedly more painful?

After the first dose of the vaccine, many people experienced some pain in the injected arm, some redness or headaches in the two days following the injection. But nothing too serious. As for the second dose, it is possible that it may cause worst reactions than the first.

On social networks, people who have been vaccinated have shared their experiences and there are many testimonies, as below:

'Stronger reactions' from the second dose

Since the beginning of the vaccination campaign, the Yellow Card Scheme has noted 267,671 cases of adverse reactions in the UK, all vaccines combined. As for the Pfizer vaccine, as of 2 June, 67,998 adverse reactions have been recorded, according to the government website. Of course, not all people who have had side effects have recorded their experiences.

In December, it had already stated that:

Systemic reactions, particularly fever, fatigue and headaches, are more important when the second dose is administered compared to the first dose.

The same is true for the Moderna vaccine.

What is the cause for these side effects?

According to a study conducted between December 2020 and February 2021 by the US Centers for Disease Control and Prevention (CDC), patients would experience more effects with the second dose.

For example, 47.8% of those vaccinated experienced fatigueafter the second dose of Pfizer vaccine, compared to 29.1% after the first dose. And 40% felt a headache after the second dose compared to 24% after the first.

The fever, headaches and fatigue are systemic reactions, particularly during the second dose. This is linked to the activation of the immune system. One can have diarrhoea, great fatigue, but these effects are of short duration and moderate intensity.