Swine flu vaccine induced narcolepsy

In Sweden, the 2009 swine flu vaccine left 150–200 children and adolescents with permanent narcolepsy — first established 3 years after vaccine approval and safety studies.

In an attempt to mitigate the swine flu pandemic of 2009, many countries mass-vaccinated their populations. One of those countries was Sweden, which used the vaccine Pandemrix. Today it serves as a cautionary tale. It teaches us that we must be careful not to confuse “no evidence of harm” with “evidence of no harm”.

The swine flu vaccination-campaign in Sweden left about 150-200 children and adolescents with narcolepsy directly attributed to the vaccine. Narcolepsy is, according to the Mayo Clinic , “a chronic sleep disorder characterized by overwhelming daytime drowsiness and sudden attacks of sleep”. Symptoms include:

Narcolepsy has severe life-altering consequences. For example, afflicted individuals may not be legally allowed (se) to drive a car, as they can fall asleep spontaneously while driving. It limits educational and professional choices and can require accommodations. Difficulty concentrating, exhaustion, and memory lapses can lead to depression. While medication can alleviate some symptoms, there is no cure.

On the benefits part of the equation, official reports estimate that the vaccine prevented around 100 deaths. It's reasonable to assume that the potentially prevented deaths were mostly elderly individuals, as mortality from influenza (se) predominantly occurs in that age group. There were several other negative side effects. Likewise, there were other estimated benefits, such as reduced hospitalizations. Even so, we will restrict our analysis to narcolepsy and potentially prevented deaths, as they were the most significant permanent outcomes.

Let us look at a timeline from the creation of the vaccine until the acknowledgement of the narcolepsy side effects. By doing so we will get a better understanding of how long it can take until a link can be established.

Timeline of the Pandemrix-Narcolepsy link

Unless otherwise stated, sourced from the official report Swedish Medical Products Agency: Swine flue, Pandemrix and Narcolepsy (se).

2006, September

Pandemrix is patented by GlaxoSmithKline. It's developed as a pandemic mock-up vaccine using another virus strain, H5N1. — Pandemic influenza vaccine (H5N1)


Pandemrix is approved as a pandemic vaccine in the European Union in accordance with then safety and efficacy demands. The decision is based on clinical trials of 5000 volunteers. The clinical trails used the mock-up strain, H5N1.

2009, April

Sweden reports its first cases of swine flu.

2009, Autumn

Additional vaccine-studies on various vulnerable groups and children are carried out and evaluated using Pandemrix with the swine-flu virus strain, A/H1N1.

2009, September

The European Commission approves Pandemrix for the use against the swine flu.

2009 Oct – 2010 April

5.3 million are vaccinated with the Pandemrix vaccine in Sweden, about 60% of the population at the time.

2010, May

The Swedish Medical Products Agency (Läkemedelsverket) publishes a summary of all suspected side effects. Of the 4380 reported side effects, not a single one is narcolepsy.

2010, Summer

The first suspected side effect of narcolepsy is reported to the health authorities. At the time the link to Pandemrix is circumstantial.

2010, August

The European Medicine Agency (EMA) starts an investigation of the possible link between Pandemrix and Narcolepsy.

2011, March

A study compares 3.3 million vaccinated to 2.5 million unvaccinated individuals between October 2009 – December 2011:

Results from a Swedish registry based cohort study indicate a 4-fold increased risk of narcolepsy in children and adolescents below the age of 20 vaccinated with Pandemrix, compared to children of the same age that were not vaccinated. The results are in line with those of a similar Finish registry study.
Swedish Medical Products Agency

2013, June

The Swedish institute for infection prevention (Smittskyddsinstitutet) estimates that the vaccination campaign has resulted in the nationwide prevention of:

Smittskyddsinstitutet (se)


349 cases of narcolepsy have been reported as a suspected side effect of the Pandemrix vaccine. As narcolepsy can also occur in individuals regardless of vaccination status, it's not possible to attribute individual cases to it. After adjusting for the incidence in the unvaccinated, The Swedish Medical Products Agency estimates that between 150–200 of the 349 reported cases can be directly attributed to Pandemrix.

The risks we do not know

Long term side effects can go unnoticed for several years. While the symptoms themselves may occur months after vaccination, it can take much longer to establish a link.

Since the narcolepsy side effect was relatively rare, it went unnoticed in clinical trials. Since narcolepsy can also occur without vaccination, it had to be evaluated over a long period of time before it could be compared to the baseline incidence with statistical confidence.

Every new intervention has risks that are inherently unknowable. To justify it, there has to be a clear upside over a potential infection. The swine flu, like most flu viruses, is responsible for virtually no deaths in children and adolescents. In the 0–39 years age group, less than 10 people typically die because of the influenza per year in Sweden. Swedish Influenza report (se).

The benefits did not justify the risks of the vaccine for children and adolescents. This observation is not only predicated upon our current knowledge of the situation, but was valid before the start of the mass-vaccination campaign. As we knew that influenza poses no serious risk to children, there were next to zero benefits for the individual child. On the other hand, every new medical intervention has unknowable potential risks. Therefore, there were no good reasons of vaccination whatsoever for any child or adolescent.

There are other benefits than individual to consider. For example, it can be argued that by vaccinating children the infection rate is slowed down which may lead to older and weaker individuals not contracting the decease, thus saving their lives. The benefit is not for the individual receiving the vaccine, but indirectly for others. This is a moral question and cannot be answered with data alone. As a personal opinion of the website, we think that it's immoral to transfer risk from the old to the young.


The Pandemrix mass-vaccination campaign was a major scandal in Sweden. The government encouraged a treatment without properly evaluating the risk-benefit equation. To potentially prevent the deaths of 100 mostly elderly, 150–200 children and adolescents suffered permanent narcolepsy.

When faced with a threat and a new potential treatment, we must remember that there are risks of the treatment that we do not and cannot know. It's inherently unknowable how a new treatment will affect us in the long term until a long time has passed. Until then, we must remain cautious and ask ourselves what the benefits truly are.


November 23, 2021

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