Data are available from the first 1000 healthcare workers who took part in the monitoring, conducted to analyse the type of response to inoculation with other important variables such as age and gender. One month after the second dose of the Pfizer-Biontech vaccine, it is clear that adverse events after vaccination are of little or no clinical relevance.

"Post-vaccination clinical monitoring is an essential phase of medical research, and the results of the survey we are conducting are extremely encouraging," said Rectress Antonella Polimeni. "Sapienza is once again deploying its resources in the fight against the pandemic, thanks also to the health professionals who have grasped the importance of the study on vaccine responses.

Specifically, 1081 subjects, aged between 24 and 69 years, 64% of whom are women, have been recruited for the study to date. 53.7 % of them did not present any adverse events after vaccination, whereas 46.3 % reported mild adverse events that started after about 12 hours and, in most cases, disappeared after 24 hours. The most common adverse effects were pain at the inoculation site, flu-like symptoms with or without fever and lymphadenopathy. Less frequently, dermatological manifestations (urticaria, erythema, angioedema), ocular manifestations (conjunctival redness, severe itching) and gastrointestinal symptoms (nausea, diarrhoea, abdominal pain) were reported. The most significant finding is that adverse events perceived as severe (syncope, chest pain, difficulty in walking, heart palpitation, confusion) occurred in only 1.2% of those vaccinated and in no case did hospitalisation become necessary.

"This study - says Fabrizio d'Alba, Director General of Policlinico Umberto I - is an important step in the "scientific journey" that our researchers are making on vaccines and adverse events. The numbers of this research, although not exhaustive, confirm even more the need to rely on science and its workers to advance the fight against the pandemic".

The study, promoted and encouraged directly by the Rectress of Sapienza University and the Director General of Policlinico Umberto I General Hospital, will include about 10,000 subjects and will aim to assess the antibody response in vaccinated individuals and to analyse the associations of such response with important variables such as age, sex, underlying medical issues and socio-economic status.