Vaccines against Covid-19 are safe and effective and the administration of a third dose can confer greater protective efficacy. This is what emerges from the study conducted on 3,720 health workers of the Irccs Policlinico San Matteo di Pavia Foundation to prospectively investigate the risk of coronavirus infection in vaccinated subjects. The work, one of the largest conducted to date, was published in the journal ‘Nature Communications’.
The results demonstrated the efficacy of vaccines in protecting against Sars-CoV-2 infection which stands at 83% in the overall population of health workers and 93% in health workers who had previously contracted the infection. Of the 3,720 vaccinated health workers, only 33 contracted Sars-CoV-2 infection, ie less than 1%; 17 were symptomatic and had mild symptoms such as rhinitis, cough and arthralgia. No one had pneumonia or needed hospitalization.
Another interesting fact concerns the transmissibility of the virus: of the 33 operators of San Matteo who became infected, only 2 of them transmitted the infection to their families. The data were compared with a group of 346 healthcare workers who had not yet received the vaccination in the period between January and April 2021. On this sample the results change considerably and testify to the effectiveness of the anti Covid-19 vaccination.
The researchers and clinicians of San Matteo have, in fact, recorded a higher rate of infection (5.78%) and also a greater number of symptomatic subjects. 85% had symptoms such as fever, anosmia (loss of smell), ageusia (loss of taste) and 10% required hospitalization due to worsening clinical conditions.
“The numbers do not need further comments – underline the researchers of the San Matteo di Pavia -. The results are more than comforting: the impact of vaccination has essentially erased the possibility of becoming infected in large numbers. There have been some cases of reinfection, but it is below 1% of the operators analyzed. Percentage that is halved for those who had had a previous infection and have completed the vaccination cycle. This tells us that more stimulations confer greater immunity, “the researchers conclude.
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