Pfizer and Moderna vaccines reduce Sars-CoV-2 infections by 90 percent

A study by the US Centers for Disease Prevention and Control shows that vaccines made with messenger RNA technology they also work in blocking Sars-CoV-2 infection and not only towards the symptoms of Covid-19, the syndrome triggered by the coronavirus.

The survey, carried out between December and March on almost 4 thousand people vaccinated in the first phase of the campaign (doctors, healthcare personnel and essential and front-line operators), gives an account of how 14 days after the first dose of the Pfizer or Moderna product the possibility of becoming infected was reduced by 80%, percentage that sale al 90% two weeks after the second dose, therefore after immunization is complete.

In fact, the contagiousness of the virus would be almost eliminated even in contexts characterized by a high risk of exposure to the virus, such as that of monitored volunteers: an essential piece of news in terms of controlling the pandemic, as well as its clinical consequences. A moment comparable to what we experienced last fall when the first results of the phase 3 clinical trials arrived.

Not only that: during the study, the various variants that for some months have given a boost to contagiousness were already widely circulating, such as B.1.1.7 identified in England or those isolated in Brazil or South Africa. Vaccines provided powerful protection even in those cases. The investigation, concluded on March 13, consisted in carrying out do-it-yourself weekly swabs for the identification of Sars-CoV-2 regardless of the state of health, i.e. the presence or absence of symptoms associated with Covid-19 . The conclusions, which compared a part of fully vaccinated volunteers, a part who had received only one dose and people not yet vaccinated, explain that licensed mRna vaccines are effective in preventing infection among adults of working age and in real-life conditions.

The network involved in monitoring includes eight sites in the United States, from Arizona to Oregon, from Utah to Minnesota), from which the volunteers independently collected nasal swabs in case of no symptoms and also saliva samples and an additional nasal swab in case of onset of symptoms comparable to those of Covid -19. The biological materials thus collected, shipped in refrigerated containers to the reference clinic, the Marshfield Clinic Laboratory in Wisconsin, were examined according to molecular analysis. They were really exciting results, like those of another survey just published in Nature Medicine according to which vaccinated people who become infected have a very low viral load.