Side effects of COVID-19 vaccines in Switzerland – update

1,953 reports of suspected adverse reactions to COVID-19 vaccines in Switzerland evaluated


As at 4 May 2021, Swissmedic has evaluated 1,953 reports of suspected adverse drug reactions (ADR) to COVID-19 vaccinations in Switzerland. The reports corroborate the side effects profile identified during the authorisation studies and described in the medicinal product information, and do not alter the positive ratio of benefits to risks of the two mRNA vaccines used.

The reports of suspected adverse drug reactions (ADR) to COVID-19 vaccinations are evaluated in collaboration with the regional pharmacovigilance centres and in particular with the Ticino reference centre (EOC cantonal hospital authority). 870 reports involve Pfizer/BioNTech’s Comirnaty®, while 1,061 are associated with Moderna's COVID-19 vaccine. In 22 cases, the vaccine was not specified. Most of the reports were submitted by medical professionals while 130 (11.8%) came directly from those affected, i.e. the patients.

According to information from the FOPH, around 2.8 million vaccine doses have been administered in Switzerland up to and including 2 May 2021, and approximately 954,000 people have been fully vaccinated. Since there is often a delay in sending reports on adverse drug reactions to Swissmedic and it also takes time to carefully evaluate them, it is not possible to directly compare the reports shown here with the vaccinations given. Retrospectively, however, there is an approximate reporting rate of one per 1,000 doses administered.

The majority of the reports concerned women (69.2%). Men were affected in 27.8% of cases, and there were a few cases (3.1%) where no gender was specified.

The average age of those affected was 64.8 years (range 16–101), with 38.1% aged 75 or over. In the cases classified as serious, the average age was 67.7, and for reports temporally linked to a death it was 82.7 years.

1,252 (64.1%) most of the reports were classified as not serious, while 701 reports (35.9%) were classified as serious. In these latter cases, the people affected were either treated in hospital (n=199) or their reactions were classified as medically significant for other reasons. In most cases, the criteria “temporary severe impairment / medically important” was the reason why the case was classified as serious (n=366).

The majority of the reports involved more than one reaction (a total of 5,118 reactions in the 1,953 reports, equating to an average of 2.6 reactions per report).

The reactions most commonly reported in the cases classified as serious were fever (90), headaches/migraine (51), shortness of breath (48), reactivation of shingles (48), exhaustion (38), muscle pain (37), malaise (34), hypersensitivity (33)/anaphylactic reactions (17), nausea (32), shivering (31), vomiting (31) and elevated blood pressure (31). As a single report generally involves more than one reaction, reactions such as fever or headache are reported in cases that are classified as serious overall as well as in non-serious cases.

Since the evaluation on 20 April 2021, 31 additional cases of herpes zoster have been reported, bringing the total to 92. The possibility of a causal connection between the vaccinations and the onset of herpes zoster is currently under investigation.

In 76 serious cases, the people concerned died at differing intervals after receiving the vaccine. Their average age was 82, and the majority of them had serious pre-existing conditions. These reports were analysed with particular care and, in a very few cases, the final results from autopsies are still pending. As far as is known at present, death was caused by conditions such as infections, cardiovascular events or diseases of the lungs and airways that occurred independently of the vaccinations, even though there was a chronological correlation. At present there are no indications globally that the two mRNA vaccines are associated with an increased fatality rate.

The reports of adverse reactions received and analysed to date do not alter the positive benefit-risk profile of the COVID-19 vaccines used in Switzerland. Any pointers to as yet unknown safety problems based on reports from within Switzerland or from abroad will be thoroughly investigated. Thus, for example, some very rare reports from around the world of immune thrombocytopenia (ITP) or inflammation of the heart muscle (myocarditis) are being discussed and analysed further. In evaluating the safety aspects of the COVID-19 vaccines, Swissmedic is also in close and regular contact with other international drug regulatory agencies. As soon as valid findings are available on possible risks, we will provide information about these and about any measures that can be taken to alleviate them.

The reports now provide us with a clearer picture of the vaccines’ safety in daily use. This largely confirms their known side effects profile. Known side effects of COVID-19 vaccines are listed in the continually updated medicinal product information texts published on

Reporting undesirable effects

Hinweise zur Meldung von UAW der Covid-19 Impfstoffe

Information on reporting ADR associated with COVID-19 vaccines

Please note: Known, non-serious reactions are not subject to the reporting obligation prescribed by Art. 59 of the Therapeutic Products Act. The known, non-serious and very common reactions to COVID-19 vaccines include transitory pain and swelling at the injection site, fatigue, shivering, fever, headache and muscle and joint pain. These passing local and general reactions are normally a sign of the body dealing with the vaccine.

However, serious or as yet unknown adverse reactions must be reported. At this relatively early stage of the vaccination campaign, doctors should generally report all ADR that they feel are medically relevant. For this purpose they should use the ElViS electronic reporting tool, which they also can log into using their HIN ID.


Comments on the interpretation of the data

Given the methodology of the spontaneous reporting system, the following factors need to be taken into account when interpreting the data presented here: The figures in this report are based on suspected reports received by Swissmedic from healthcare professionals, affected individuals or pharmaceutical companies and entered in the database following a review and evaluation.

All the reported reactions are suspected cases. This means that, in individual cases, it has not been ascertained whether the reported reaction was merely observed around the time of the vaccination or was actually caused by it. The possible causality is also investigated as part of a careful analysis of the cases.

Since not all reactions are reported, the figures presented here do not allow any reliable conclusions to be drawn about the number of reactions that have actually occurred. The number of suspected cases for each vaccine can depend greatly on how many people received this vaccine in the period in question. The figures for suspected cases of vaccination reactions are just one of many factors considered in the ongoing assessment of the risk-benefit profile of vaccines. Swissmedic incorporates the findings from the spontaneous reports in the scientific analysis of all the available data in order to be able to draw correct conclusions about the safety profile of a vaccine.