Internationally binding criteria exist for classifying a suspected adverse reaction to a drug or vaccine as "serious". It is always classified as serious if the suspected adverse reaction was life-threatening, resulted in hospitalisation or prolonged an existing hospitalisation, or in cases involving a fatal outcome. Cases are also considered to be serious if they have resulted in disability or permanent damage that caused substantial disruption to a person's ability to conduct normal life functions. If the administration of a drug to a pregnant woman has led to an adverse reaction or damage in the newborn child, this situation should always be classified as serious. Another criterion for classifying a case as serious is whether it is described as "medically important" or resulting in "temporary severe impairment". This criterion often leads to misunderstandings. It refers to cases in which the affected individuals were specifically at risk and required a medical intervention in order to prevent serious damage in terms of the above-mentioned criteria.
Criteria for a serious adverse reaction to a drug or vaccine:
- Hospitalisation or prolongation
- Persistent damage or disability
- Congenital anomaly
- Medically important / temporary severe impairment (medical intervention required)
Occasionally, the criterion of "medically important/temporary severe impairment" is checked inappropriately in reports of suspected reactions. Thus, for example, a person can experience a fever after a vaccination and feel ill for several days, or have severe headaches and joint pains, and yet the case is not "serious" according to the categories described above. Although such symptoms are obviously "severe" or "pronounced" for the individual concerned, and thus very unpleasant and stressful, the crucial aspect of a specific medical threat is lacking.
As regards reports of suspected adverse reactions submitted to Swissmedic, the reporting individuals themselves decide whether to classify the effect as serious and according to what criterion. Even if the information on seriousness proves to be incorrect on inspection, the classification is not usually changed by Swissmedic according to the standard international procedure in drug safety: this means that a case reported as "serious" is not downgraded to "non-serious". A correction is made only in exceptional cases, and then only for the purpose of "upgrading". This may be the case, for example, if an adverse reaction was incorrectly classified as "non-serious" on the basis of further information in the report, and is clearly classified as "serious" by Swissmedic.
However, the incorrect application of the seriousness criteria in reports of suspected reactions to the COVID-19 vaccines can lead to an overestimation of the number of "serious" side effects. In this context, around 2,160 suspected reports from more than 9.5 million administered vaccine doses were reported to Swissmedic as "serious".
In less than half of these cases the clear criteria (hospitalisation/prolongation 31.7%, life-threatening 5.3%, death 6.3%, permanent damage or disability 3%) were stated as the reason for classifying them as "serious". In 53.6% of cases, "medically important/temporary severe impairment" was checked by the reporting individuals.