The Post-Acute COVID-19-Vaccination Syndrome in the Light of Pharmacovigilance

<b>Background/Objectives:</b> Clinical studies show that SARS-CoV-2 vaccination sometimes entails a severe and disabling chronic syndrome termed post-acute-COVID-19-vaccination syndrome (PACVS). PACVS shares similarities with long COVID. Today, PACVS is still not officially recognised as a disease. In contrast, long COVID was registered by health authorities in December 2021. Here, we address possible reasons for that discrepancy. <b>Methods:</b> We analyse whether common symptoms of PACVS have been registered by European pharmacovigilance as adverse vaccination reactions and which consequences have been drawn thereof. <b>Results:</b> (i) PACVS is distinguished from normal vaccination reactions solely by prolonged duration. (ii) Symptom duration is poorly monitored by post-authorisation pharmacovigilance. (iii) PACVS-specific signals were faithfully recorded by pharmacovigilance systems but have not prompted appropriate reactions of health authorities. (iv) The most widely applied SARS-CoV-2 mRNA-vaccine has been modified after roll-out without renewed phase III evaluation; the modification has increased DNA contaminations suspected to extend the spectrum of adverse events. (v) Crossing of pharmacovigilance data with corresponding estimates of applied vaccine doses suggest a PACVS prevalence of 0.003% in the general population. In contrast, occupational surveillance studies suggest a PACVS prevalence of 0.9% in young and middle-aged persons. <b>Conclusions:</b> (a) Denial of official recognition of PACVS is unjustified. (b) PACVS seems to target preferentially young and middle-aged persons. (c) Without official disease recognition, access to public healthcare and welfare services is made difficult for PACVS-affected persons, which creates considerable socio-economic problems. (d) Without official disease recognition, development and evaluation of PACVS therapies is impaired.