Covid vaccine, negative efficacy and vaccinated infections: fake news

The information according to which, according to ISS data for some age groups, the effectiveness of the vaccine is ‘negative’ with a greater risk of infection for the vaccinated is ‘fake news’. The Higher Institute of Health (Iss) reiterates this in the update of the section on its website dedicated to ‘hoaxes’ on anti-Covid vaccines. The analysis on the efficacy of vaccines for the age groups over 11 years is presented weekly by the ISS in its extended report, “and clearly highlights an increase in vaccine efficacy after administration of the booster dose, in all age groups. age, both in the prevention of Sars-CoV-2 infection and severe disease, compared to full vaccination with two doses “. The fact that some “apparently incongruent” data are present (for example, in some cases the efficacy in vaccinated with a full course of 91 – 120 days is lower than the efficacy in vaccinated with a full course of more than 120 days), is to be attributed to some intrinsic limitations of the analysis – the ISS experts explain – The most important is the fact that due to the spread of the highly transmissible variant Omicron, there has been a sharp increase in the proportion of people who have had an infection which however has not been notified “. In the analysis these people are ‘unvaccinated’, but in reality they have a protection given by the previous infection, with a consequent underestimation of the calculated efficacy. “Furthermore, many people who had two doses did not take the third because they contracted the infection, another phenomenon that may explain why for some people the efficacy is greater for people who have been immunized for longer. In light of these considerations and for to reduce the bias in results caused by under-reporting of less severe infections, a review is underway of how the efficacy data is analyzed, “warns the ISS. As regards the efficacy of vaccination in the 5-11 year range, it is emphasized that the data “is not calculated in the extended report, but given the peculiarity of the population is the subject of a specific study that will be published as soon as it is available – concludes the Institute – The incidence values ​​reported in the document are to be considered indicative because they do not take into account possible confounding factors that require more complex models “.