What's worse? The vaccine side effects or the illness brought on by the SARS-CoV-2 virus? Science.lu checks the facts.

Reactions and side effects have played a huge role in discussions since the first SARS-CoV-2 vaccines were developed. But how are we meant to classify the overload of information and headlines? What about the proportionality of the risks of getting seriously ill with Covid-19 on the one hand and suffering side effects stemming from the vaccinations on the other?

A complete picture is only made possible through comparing the vaccine reactions and side effects side-by-side with the symptoms of Covid-19 disease. The choice between getting vaccinated or not is about a risk / harm-benefit calculation. What are the risks and harms of Covid-19 compared to the benefits and risks / harms of the vaccination?

The path to herd immunity takes time and patience. In order to reach the stage when un-vaccinated people are sufficiently protected by immunised people, many, many more need to achieve immunity, whether through vaccination or recovery from the virus. Even then, outbreaks are still likely to occur among the non-vaccinated or insufficiently immunised population. Professor Dr Claude Muller, virologist at the Luxembourg Institute of Health (LIH), describes it thus:

"A choice between the virus and vaccination"

"From my point of view, there is a choice between the virus and the vaccination. Of course, you could isolate yourself completely for a long time, stop travelling, and reduce personal contacts to an absolute minimum. But this does not seem practical to me, especially for the population of Luxembourg, who travel frequently."

We therefore asked the question: what happens statistically when a person is infected? And what happens when that person is vaccinated? Rather than focusing merely on percentages and probabilities, we compared 100,000 people sick with Covid-19, with the same number of people vaccinated against Covid-19.

Note: We consider anyone who has received a dose of one of the various approved vaccines to be vaccinated. If a second dose is necessary for the respective vaccine, there remains a risk of the adverse reactions described here.

We reached out to Professor Dr Claude Muller for his expert opinion on dissecting the data available. The virologist at the Luxembourg Institute of Health has researched immunisation against various infectious diseases around the world for many years.

Data valid as of 19 April 2021.

Comparison: 100,000 Covid-19 patients and 100,000 vaccinated people 

Minor side effects Covid-19 illness Reaction to jab
Cough 40,000 no data available
Fever 27,000 36,600
Fatigue 31,000 62,900

Severe effects and long-term consequences Covid-19 illness Reaction to jab
Hospitalisation 10,000 8.4
Intensive care 1,400 1.94
Deaths 860 0.65*
Sinus vein thrombosis 4 0.65
Long Covid (long-term effects) 2,300 0 - none reported to date

The data situation is still complicated. A large number of sources were identified for this article and compared with one another. Although the data is expected to become more advanced as the vaccine rollout continues, the situation presented here is fairly clear already. Both the virus and vaccines present a certain number of risks, but it is apparent that the virus is more likely to risk serious illness than the vaccine. That said, more studies and data will be required to achieve even more precise figures. 

Overview of Covid-19 symptoms

The chart shows the proportion of 100,000 Covid patients who suffer from selected symptoms, as well as those who developed a serious illness, Long Covid, and Covid fatalities. The numbers vary depending on the examinations used.

Covid-19 patients  Number of patients affected
No symptoms 17,000
Cough 40,000
Fatigue 31,000
Fever 27,000
Loss of smell/taste 22,200
Severe cases  
Hospitalisation 10,000
Long Covid 2,300
Intensive care 1,400
Deaths 860
Ventilator/ other invasive procedure required  784
Brain blood clots 4

Overview of vaccination reactions and complications

This chart depicts the number of people who experienced symptoms or complications following a SARS-CoV-2 vaccine (either BioNTech / Pfizer Comirnaty or AstraZeneca). The figures hail from the phase 3 studies used by the EMA for drug approvals. Blood clots in the brain are an exception. While there was nothing in the studies to suggest that any of the approved vaccines could cause such a clot, this link was evident during vaccinations with the AstraZeneca vector virus vaccine. However, just over 220 cases were registered from around 34 million vaccinations.

Data has also been added for the placebo group.

Symptoms BioNTech/Pfizer (average, EMA data) AstraZeneca (average, EMA data) Placebo group, clinical study of BioNTech/Pfizer first dose
Pain at  injection site 84,100 54,200 14,000
Fatigue 62,900 53,100 33,400
Headache 55,100 52,600 33,700
Muscle aches 38,300 44,000 10,800
Fever 14,200 33,600 900
Pathologically swollen lymph nodes 300 No data No data
Allergic reactions 630 No data No data
Anaphylaxis 1 No data No data
Brain blood clots No data 0.5 No data
Deaths linked to vaccine 0 0 /

The figures depicted above are all averages. The risk varies according to age and prior medical conditions.

Authors: Kai Dürfeld (Science RELATIONS ), Jean-Paul Bertemes (FNR)