Reports of suspected adverse reactions to the COVID-19 vaccines in Switzerland

Since the concluding standard report on adverse reactions to the COVID-19 vaccines in Switzerland was published at the end of February 2023, an additional 720 suspicion reports have been evaluated. For an estimated 17 million vaccine doses¹ administered to date in Switzerland, Swissmedic received a total of 17,575 reports of suspected reactions in connection with the COVID-19 vaccines up to 30 June 2024.

Of these, 10,626 (60.5 %) reports were registered as “non-serious”, and 6,949 (39.5 %) were declared – mainly by the reporters themselves – as “serious”². The average age of the people affected in these cases was 52.7 years.

Across all the reports, well-known vaccine reactions such as fever, headache and limb pain, fatigue, chills, redness, pain or swelling around the injection site and nausea were most common. This corresponds to the reactions identified in the authorisation studies and the monitoring studies following market launch.

In isolated cases, longer-lasting symptoms are described with a temporal relationship to a vaccination against COVID-19 which caused severe impairment in those affected and can also occur after infection with the coronavirus SARS-CoV-2 as post- or long COVID³. The symptoms indicated are very wide-ranging and sometimes exhibit similarities with long COVID disease and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)⁴. In view of the very high infection rate with SARS-CoV-2, how to classify cases as long COVID has not yet been scientifically clarified. Swissmedic evaluates reports of such cases thoroughly, continually reviews the latest drug safety findings, follows the medical science literature, and is in regular contact with international partner authorities.

The extent to which longer-lasting complaints in vaccinated individuals can actually be attributed to the vaccination needs to be reviewed by means of careful diagnoses and analyses. Swissmedic appeals to healthcare professionals reporting suspected cases to provide details of the patient’s previous medical history and the diagnostic procedures followed so that all available clinical information can be taken into account in the scientific evaluation.

¹ _{This includes both basic immunisation and booster vaccinations. The information is based on the most recent data available on the COVID-⁠19 dashboard Switzerland as at 3 July 2023 (www.covid19.admin.ch)}

² _{When entering the cases, the reporting individuals themselves defined whether they classified the reactions as serious or non-serious. According to international pharmacovigilance practice, this categorisation is only revised during evaluation by Swissmedic in exceptional cases – e.g. for events that were reported as “non-serious” if they are subsequently classified as “serious” on the basis of further information.}

³ _{Long COVID is not one single disorder, but is rather a range of possible long-term effects on health following a previous SARS-CoV-2 infection. The WHO defines long COVID as the continuation or development of new symptoms 3 months after the initial SARS-CoV-2 infection, with these symptoms lasting for at least 2 months with no other explanation. The various symptoms, which last for varying amounts of time, may occur separately or together, persist for a long time or appear repeatedly, thus severely impairing the person’s quality of life. The underlying mechanisms have not yet been sufficiently clarified, although new research findings are constantly being added. Studies have shown that many of those affected have impairments in the T-cellular immune system. However, similar reactions could also be caused by other viral infections.}

⁴ _{In the context of COVID-19 vaccinations, certain highly heterogeneous and generally prolonged symptoms that have occurred in vaccinated individuals with a temporal relationship to vaccination are also referred to as “post-vaccine syndrome”. At present, there is no recognised standard definition of post-vaccine syndrome.}

Gender and age differences

10,786 (61.4 %) of the reports received between 1.1.2021 and 30.6.2024 refer to women, and 6,243 (35.5 %) to men. No gender was specified in some of the reports. There are various reasons (e.g. biological differences, social factors such as health awareness or variable behaviour in terms of health communication and care) that mean that women report adverse drug reactions more often than men.

Reports of suspected adverse drug reactions (ADRs) from COVID-19 vaccines are most frequent in the 18-44 age group, followed by the 45-64 age group. No age was specified in more than 2,000 cases. The average age of those affected was 50 years.

Vaccine reactions

Most of the reports involved more than one reaction. In total, 54,920 reactions were reported, corresponding to an average of 3.1 reactions per case. The following reactions were reported most frequently for all COVID-19 vaccines:

In the 10,626 reports classified as non-serious, the following vaccine reactions were reported most frequently:

In the 6,949 reports classified as serious, the following vaccine reactions were reported most frequently:

In 249 of the serious cases, a fatality was reported at differing intervals after receiving the vaccine. The average age of those who died was 77.4 years. Despite the temporal association, it was not possible to infer causality on the basis of the documents submitted and evaluated for each case. Neither did any international controlled observational studies indicate increased mortality following COVID-19 vaccinations.

Report sources

Under the Therapeutic Products Act (TPA), healthcare professionals are obliged to report serious and previously unknown or insufficiently known adverse drug reactions (ADRs) to Swissmedic.

44.5 % (7,818) of reports were made by healthcare professionals. The general public can also report suspected adverse effects of medicinal products; 55.5 % (9,757) came from those directly affected or from patients’ relatives.