New Confirmed Side Effects of Pfizer and Moderna Vaccines

Spain has already started the booster shot vaccination campaign, in which doses of Pfizer and Moderna vaccines will be used. Two drugs on which new side effects have been registered, according to the ninth pharmacovigilance report of the Spanish Agency for Medicines and Health Products (AEMPS).

New Confirmed Side Effects of Pfizer Vaccine

1. Erythema multiforme. It is an inflammatory reaction of the skin characterized by targeted skin lesions, with the darker center surrounded by paler rings. The pharmacovigilance system, the PRAC, of ​​the European Medicines Agency (EMA) has concluded that it may be an adverse reaction and should be included in the technical data sheet and the package leaflet. In Spain, until October 3, 2021, there have been two notifications of erythema multiforme after the administration of Pfizer; Up to that date, about 49.6 million doses of this vaccine had been administered.

2. Paresthesia and hypoesthesia. The PRAC has concluded that paresthesias (strange sensation on the skin, such as tingling or chills) and hypoesthesias (decreased skin sensitivity), should be added as possible adverse reactions in the Comirnaty SmPC and package leaflet. In Spain, up to October 3, 2021, 1,010 reports of paresthesia and hypoesthesia have been registered after the administration of Pfizer. H

3. Asthenia, lethargy, decreased appetite and nocturnal hyperhidrosis. In the context of the review of the data that are produced through ongoing clinical trials, the following possible adverse reactions have also been added to the technical data sheet and the package insert: asthenia (lack of energy or strength), lethargy (state of indifference and inactivity), decreased appetite and hyperhidrosis (excessive sweating) at night. These possible adverse reactions are considered rare (they occur in less than one in 100 people).

New Confirmed Side Effects of Moderna’s Vaccine

1. Erythema multiforme. The PRAC has also concluded that there is a possible mechanism by which Moderna’s vaccine can cause erythema multiforme, therefore, it should be included in its technical data sheet and package insert. In Spain, until October 3, 2021, a notification of erythema multiforme has been registered after the administration of Moderna. To date, about 8.8 million doses of this vaccine have been administered.