Side effects of COVID-19 vaccines in Switzerland – update

2,269 reports of suspected adverse reactions to COVID-19 vaccines in Switzerland evaluated


Up to 18 May 2021, Swissmedic evaluated 2,269 reports on 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). 971 (42,8%) reports involve Pfizer/BioNTech’s Comirnaty®, while 1,269 (55,9%) are associated with Moderna's COVID-19 vaccine. In 29 (1,3%) cases, the vaccine was not specified. Most of the reports were submitted by medical professionals, while a relatively large number (302, or 13.3%) came directly from those affected, i.e. the patients.

According to information from the FOPH, around 3.7 million vaccine doses have been administered in Switzerland up to and including 18 May 2021, and approximately 1.24 million 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, the reporting rate has declined somewhat in the last few weeks, dropping from 1 to 0.8 per 1,000 doses administered.

The majority of the reports concerned women (1551, 68.4%). Men were affected in 640 (28.2%) of cases, and there were a few cases (77, 3.4%) where no gender was specified. The average age of those affected was 63.6 years (range 16–101), with 815 (35.9%) aged 75 or over. In the cases classified as serious, the average age was 67.3 years, and for reports temporally linked to a death it was 82.4 years.

At 1,447 (63.8%), most of the reports were classified as not serious, while 822 reports (36.2%) were classified as serious. In these latter cases, the people affected were either treated in hospital (n=237) 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=430).

The majority of the reports involved more than one reaction (a total of 5,931 reactions in the 2,269 reports, equating to an average of 2.6 reactions per report).

The reactions most commonly reported in the cases classified as serious were fever (103), headaches/migraine (61), shortness of breath (54), reactivation of herpes zoster (61), exhaustion (41), muscle pain (41), malaise (37), hypersensitivity (36)/anaphylactic reactions (20), nausea (36), shivering (35), vomiting (34) and elevated blood pressure (34). 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.

Up to the date of this analysis, 121 cases of herpes zoster (shingles) had been reported. The possibility of a causal connection between the vaccinations and the onset of herpes zoster is currently under investigation.

In 84 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 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