Last updated on 20.09.2021

Side effects, myths & questions

Side effects

Vaccines are authorised by Swissmedic only if they are safe and effective. They are thoroughly tested to this end.

The risk of serious complications of an infection with coronavirus is many times higher than the likelihood of suffering severe side effects of the COVID-19 vaccination. In other words: it is the coronavirus that poses a threat, not the vaccination.

Pfizer/BioNTech have tested the vaccine in a trial with 43,000 participants. Half of the tested individuals received the COVID-19 vaccine, while the other half received an inactive placebo. Trial participants experienced classic side effects that also occur after other vaccinations. Aside from mild local reactions around the injection site, the following side effects were observed in those inoculated with the COVID-19 vaccine:

  • Fatigue
  • Headache
  • Muscle pain
  • Joint pain
  • Shivering
  • High temperature

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These symptoms were short-lived. They often occur after vaccinations and show that the body is building protection against the disease. So when they are mild they are a good sign.

Rare side effects, or those that occur after several months, have not yet been observed in the study. But the study results to date clearly demonstrate that the risks of coronavirus disease are much higher than the risks associated with the vaccine.

It is a similar story for the side-effects of the Moderna vaccine: half of the 30,000 or so people taking part in the trial were given the COVID-19 vaccine, while the other half received a placebo. Here too the symptoms were classic. In addition to minor reactions around the injection site, the following side-effects were observed:

  • Fatigue
  • Headache
  • Muscle pain
  • Joint pain
  • Shivering
  • High temperature
  • Nausea/vomiting
  • Swollen lymph nodes

Any vaccination can have side effects, but severe side effects are clearly the exception.

Since they were authorised in late 2020/early 2021, more than a billion people worldwide have been inoculated with these vaccines. Serious side effects have been very rare. For example, some people experienced a severe allergic reaction straight after receiving an mRNA vaccine. In very rare cases, inflammation of the heart muscle or tissues surrounding the heart has been observed within 14 days of the vaccination. These cases were mostly mild and easily treatable. The link to vaccination is currently considered possible. However, such infections are much more common in people infected with coronavirus than after the vaccination.

Based on data from international notification systems, no indications of other severe side effects habe been observed to date. These sorts of side effects would be expected within several months of the vaccination. Experts continue to closely monitor potential indications.

In Switzerland, the independent therapeutic products agency Swissmedic is responsible for authorising and monitoring COVID-19 vaccines. It regularly publishes reports on suspected adverse reactions from health professionals and the public in connection with the COVID-19 vaccination in Switzerland. Health professionals are only legally required to report unexpected and serious side effects. This explains why the majority of the reported side effects are serious. You can find detailed information at: www.swissmedic.ch/covid-19-vaccines-safety-update-en.

Since December 2020, over 150,000 pregnant women in the United States have been vaccinated with mRNA vaccines against COVID-19, with a similar side effect profile as the rest of the population. In a specific monitoring study for pregnant women which has been running since early 2021, vaccination was not found to have any adverse effects on the pregnancy or the development of the child.

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How is the safety of vaccines monitored?

Check out the video to see what’s involved in monitoring vaccines.

Allergic reactions after the COVID-19 vaccination are very rare

Over half of the Swiss population has been vaccinated. There have been very few severe side effects such as serious allergic reactions. Any such reaction will usually occur immediately after vaccination and can be effectively treated. To illustrate the likelihood of such a side effect occurring with the COVID-19 vaccine, here it is compared with other causes of allergic reactions.

Fact check

A number of false reports, rumours and myths are circulating in connection with the COVID-19 vaccination. Here you’ll find important facts about the vaccination, including scientific explanations.

#1 DNA

Fact:

Your genes remain unchanged by the mRNA vaccine.

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Claim:

The mRNA vaccine can change my human genome.

Explanation:

The fact is that the mRNA in the vaccine does not enter the protected cell nucleus where your genetic material (DNA) is located. The vaccines that are currently approved in Switzerland use the mRNA in order to produce virus proteins in your body, which teach it to recognise the coronavirus. Your immune system will quickly render the coronavirus harmless if you come into contact with it in future. In this video, you can find out more about how an mRNA vaccine works.

#2 Fertility

Fact:

The vaccination has no impact on fertility.

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Claim:

The vaccination can affect fertility.

Explanation:

The COVID-19 vaccination has no impact on fertility. Vaccination is safe. It is also safe if you want to get pregnant soon or at some time in the future. It likewise has no effect on the future development of the placenta or the course of a future pregnancy. You can receive the vaccination at any time during your menstrual cycle. You can also get vaccinated if you are breastfeeding.

Following vaccination, your body recognises the coronavirus by its typical spike proteins and is able to fight the virus in a very targeted manner.

All of the vaccines that have been authorised in Switzerland are tested carefully as regards their safety. Fertility problems have never been reported as a side effect of a vaccination. The COVID-19 vaccines are no exception and their safety continues to be monitored closely. Further information on the topic of fertility can be found on the FOPH website. Professor Claire-Anne Siegrist, infectious disease expert, also explains the topic in this video.

Find out more about the infertility vaccination claim in the following two videos:

The video from the Watson news portal contains a clear explanation of why there’s absolutely no basis to the claim and why there’s no reason for men or women to worry about their fertility.

Here various midwives explain why they advocate the vaccination.

#3 Virus variants

Fact:

The vaccine is also effective against virus variants.

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Claim:

There is no point in getting vaccinated, as the vaccine will not work against new virus variants.

Explanation:

All viruses change naturally as long as they are circulating within the population.. The latest findings show that the approved mRNA vaccines also offer protection against all virus variants identified so far. While initial data shows that the protection offered against being infected with the Delta virus variants is slightly reduced, the protection provided against falling ill with a serious case of COVID-19 is not compromised. The good news is that researchers are working on booster vaccines that will specifically target both current and future variants. When and whether such booster vaccines will be required is currently unknown. However, the situation will be monitored closely. As long as there are people who are not fully vaccinated, there is a greater chance that a newly emerging variant can spread. The more people who are vaccinated, the more the impact of such variants can be reduced. Vaccination is a good measure for decreasing the likelihood of such variants occurring. Giorgio Merlani, Chief Medical Officer for the Canton of Ticino, also explains the topic in this video.

#4 Speed of development

Fact:

The safety of the vaccines is guaranteed despite the rapid development and testing phases.

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Claim:

A vaccine that is developed and tested so quickly cannot be safe.

Explanation:

The global impact of the pandemic created an extraordinary environment for bringing vaccines to market so quickly. Various stakeholders came together to provide the required financial and logistical resources. The various phases of the clinical studies were completed in parallel and not one after the other as is usually the case. This saved a lot of time. As the population recognised the risk presented by the virus, there were many volunteers prepared to come forward and participate in the clinical trials. Many wanted to help ensure a safe and effective vaccine became available. The trials were very large, included many participants and thus also generated vast amounts of data for the monitoring of any potential side effects. More information on the COVID-19 vaccine development can be found in this graphic.

Research in the area of mRNA technology was already in full swing prior to the pandemic, having begun more than a decade ago. The scientists worked together closely in order to make this technology usable using the existing infrastructure. Swissmedic, the Swiss Agency for Therapeutic Products, is the approval and control authority for medicines and medical devices. Swissmedic has the role of authorising and monitoring vaccines in Switzerland. When the first results from the clinical trials were available, Swissmedic already began a rolling review of the data (under normal circumstances, all trials are completed first before the review process commences). This procedure allowed Swissmedic to already review the available results while the final trials were still being conducted without altering its high safety standards. The requirements with respect to efficacy and safety are the same as they are for any other vaccine authorised in Switzerland. All COVID-19 vaccines that are authorised and recommended in Switzerland have a strong safety profile and high efficacy and are continuing to be monitored during their use. Dr Anita Niederer-Loher also explains the topic in this video.

#5 Long-term safety of the vaccines

Fact:

No long-term side effects are expected from mRNA vaccines.

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Claim:

mRNA vaccines are new and cause long-term side effects.

Explanation:

Based on established scientific knowledge about the immune system and the body’s response to a vaccination with an mRNA vaccine, the scientific community is convinced of the long-term safety of the mRNA vaccines that are currently authorised and recommended in Switzerland. As COVID-19 (SARS-CoV-2) has only been around for a short time, it was not possible to conduct long-term trials specifically for COVID-19 vaccines prior to the launch of the vaccination campaigns. We know from other vaccines that most adverse vaccination reactions (AVRs) occur shortly after the vaccination. Experience has shown, however, that severe AVRs are very rare and would primarily show up within a matter of months after vaccination. This period has already been covered by the vaccine approval trials, which run for more than six months with tens of thousands of people. Monitoring will also continue in future.

In addition to the solid data on the mRNA vaccines gathered during the clinical trials, we now also have experience from the vaccination campaigns. Many hundreds of millions of people around the world have now received the vaccine and the vast majority have had no problems subsequently. In those countries that are already vaccinating their populations, adverse vaccination reactions and potential late effects are continuously monitored. With the large number of people receiving the vaccine and the intensive monitoring of the regulatory authorities around the globe, any problem would be quickly detected.

Switzerland has a strict approval process for vaccines and a robust system in place for monitoring safety. This guarantees that the Swiss population has access to safe vaccines. The standards set by Swissmedic have proven to be sound time and again since their inception. These standards ensure the long-term safety of the vaccines authorised in Switzerland.

#6 Risks vs benefits

Fact:

The benefits of the vaccine outweigh the risks.

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Claim:

The side effects of the mRNA vaccination are worse than a natural infection.

Explanation:

mRNA vaccines have already been administered to millions of people. If significant severe side effects were to occur, the large number of vaccinated people means that this would be known by now. This is because adverse vaccination reactions (AVRs) that are observed after vaccination must be reported. The safety of the vaccines is being continuously and intensively monitored by Swissmedic. All reported adverse vaccination reactions can be viewed on the Swissmedic website. The risks arising from an infection with the coronavirus are significantly greater than the risks of a recommended COVID-19 vaccination. Falling ill with COVID-19 can be dangerous and associated with long-term adverse health effects (e.g. long COVID). mRNA vaccines are developed in a process that continually looks at safety. The mRNA vaccines offer robust protection against suffering a serious case of COVID-19 and against long-term consequences – this is true for all age groups.

#7 Super strains

Fact:

The vaccine reduces the likelihood of mutations.

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Claim:

The vaccine increases the risk of dangerous virus variants emerging.

Explanation:

The vaccines authorised in Switzerland have a strong safety profile and high efficacy. They do not contain coronaviruses. Therefore, vaccination can neither make you sick nor is it possible for you to pass viruses on to other people. Instead, the vaccine provides the body with instructions for how it can recognise the coronavirus and build an effective immune response against it. Vaccination prevents the spread of the virus. The more people who are fully vaccinated, the fewer new virus variants can emerge.

#8 Previous infection

Fact:

People who have already been infected with the coronavirus also benefit from being vaccinated.

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Claim:

There is no point in getting vaccinated if you have already been infected with the coronavirus.

Explanation:

It is currently unclear how long the protection lasts after infection. We know that it is possible to get infected with the coronavirus again. In principle, you are protected against a new infection for a while after being infected, but we don’t know for how long. However, there are indications that vaccinated people are better protected against infection than those who have recovered from COVID-19. To guarantee optimal protection, vaccination is recommended within three months of infection. From four weeks after a confirmed coronavirus infection, one vaccine dose is sufficient. A second dose of the vaccine is not required. As a COVID-19 infection can be associated with serious health risks, it is advisable to ensure you have the best possible protection through vaccination.

#9 Testing positive

Fact:

Vaccination cannot trigger a positive test result.

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Claim:

The COVID-19 vaccination can cause a positive test result.

Scientific explanation:

You cannot get COVID-19 due to the vaccination. The vaccines do not contain any coronaviruses. Vaccination does not cause a positive PCR or rapid antigen test either. The vaccines contain pieces of the virus – or in the case of the mRNA vaccine – induce the production of very small pieces of the virus. However, these are not detected by the tests. Furthermore, the test and the vaccination are performed in completely different areas of the body: the swab for the test is taken in the nose or the throat, while the vaccination is given in the upper arm muscle. The response of the body’s own immune system to the vaccination subsequently takes place locally and is limited to the upper arm. It is not possible for components of the vaccine or products produced by the vaccination to make their way from the arm to the nose/throat area.

This means that no component of the vaccines can infect you with the coronavirus or give rise to a positive test result.

#10 Protection given by vaccination

Fact:

Like all other vaccines, the COVID-19 vaccine does not offer perfect protection against infection.

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Claim:

Once you’re vaccinated, you can no longer be infected with coronavirus.

Explanation:

The COVID-19 vaccines authorised in Switzerland are highly effective. Unvaccinated people are much more likely to be infected than vaccinated people. However, no vaccine is 100% effective, and infection can still occur despite vaccination. The latest data show that most of these infections are mild and do not last long. Only in very rare cases do infections in vaccinated people result in serious illness and hospitalisation. At the moment, the majority of people being admitted to hospital due to COVID-19 are not vaccinated. As over time more and more people will be vaccinated, the proportion of infections in vaccinated people will increase, which is to be expected. You can draw a parallel with the introduction of car seat belts. If 100% of the population wears a seat belt, the number of fatal car accidents decreases. But if an accident does occur, 100% of accident victims will be wearing a seat belt. This doesn’t mean that seat belts don’t work. When more and more people are vaccinated, the number of infections will fall. A larger proportion of the remaining infections will occur in vaccinated people. But that doesn’t mean that vaccines don’t work. On the contrary: they are the most effective tool we have at our disposal to end this pandemic.

Expert videos on common vaccination myths.

Anyone who’s keeping themselves informed about COVID-19 will also be encountering false reports around the vaccines. Our experts and vaccination specialists Dr Anita Niederer-Loher, Professor Christoph Berger, Chief Medical Officer for the Canton of Ticino, Giorgio Merlani and Professor Claire-Anne Siegrist assess the myths that are currently doing the rounds from a scientific point of view.

On migesplus.ch, the media platform for the migrant population, you’ll also find videos in many other languages.

Frequently asked questions