Well the administration of the third dose. The arrival of the Delta dropped infection protection in the general population from 84.8% to 67.1%
remained high in Italyefficacy of mRna vaccines in the first months of vaccination in the general population, while, with regard to infection, one was observed reduction of efficacy over time for the immunocompromised and frail, who is now being given the third dose anyway.
Always good, however, the protection against hospitalizations and deaths, even if the arrival of the Delta variant has changed some factors.
Data from 29 million people
the summary of the fourth report (just released) edited by the Working Group of the Istituto Superiore di Sanit (ISS) and the Ministry of Health entitled COVID-19 vaccine surveillance on the joint analysis of the data of the integrated Covid-19 surveillance (the one that issues the weekly report) and the national vaccine register. The research was done by taking into account data from 29 million people who received at least one dose of mRna vaccine (Pfizer or Moderna), followed up until August 29, 2021. Efficacy was assessed by comparing the incidence of (symptomatic) infections. and asymptomatic), hospitalizations and deaths at different time intervals after the second dose, with that observed in the 14 days after the first dose, considered as the control period.
The results in general, for the population and all the months taken into consideration, confirmed a high efficacy of vaccines against the most serious outcomes of Covid-19 and a good resistance also against contagion, except for the numbers of some specific groups and with a separate discussion to make on the arrival of the Delta variant.
The results: 96% severe Covid protection
In particular, seven months after the second dose in the general population there is no significant reduction in efficacy in terms of protection from infection (symptomatic or asymptomatic), which remains of the89%. Even against hospitalization and death protection remains high (96% and 99%), even six months after the second dose.
The situation is different for the immunocompromised people, whereby a reduction of the protective effect against infection is observed starting from 28 days after the second dose. The report does not specify a number because the data are not homogeneous, given the small number of subjects in this group and the diversity of diseases in this category.
Even in people with comorbidit a reduction in protection against infection is observed, from 75% after 28 days from the second dose to 52% after seven months.
Finally, the effectiveness against infection in people decreases, but only slightly over 80 years old and in residents of the RSA, which still remains above 80%.
The data are consistent with those obtained from the comparison with the unvaccinated, published weekly in the extended ISS report.
These results support the decision on the administration of third doses, which began with the frail, the over 80s and residents of the RSA.
Further decline with the Delta variant, but not for hospitalizations
Different speech is made by the report regarding the arrival of the Delta variant. The numbers are in fact only about two months, but they are important because the Delta is now prevalent in Italy. Comparing the data between January and June 2021, the period in which the Alpha variant predominated, with those between July and August, mainly Delta, a reduction in efficacy against infection from 84.8% to 67.1%.
The effectiveness against hospitalizations remains high (from 91.7% to 88.7%).
These numbers seem more related to the decline in vaccine efficacy over time in the face of a highly contagious variant, rather than to the presence of the Delta variant alone or to people’s behaviors. This is because they are numbers in line with those observed in a specific study on Delta and the Pfizer vaccine just released: in the presence of the Delta variant the protection against contagion decreased from 93% to 53% after 4 months, but the protection against hospitalization remained high. , 93%, even 3-4 months after full vaccination (details in the article WHO
).
October 6, 2021 (change October 6, 2021 | 17:41)
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