MILAN (Reuters) - Seven months after the second dose, there is no reduction in the efficacy of COVID-19 mRNA vaccines in the general population in Italy, while a slight decline is seen for some specific groups, the National Health Institute (ISS) said on Wednesday.
The report led by ISS and the health ministry examined data up to Aug. 29 from more than 29 million people who had received two doses of an mRNA vaccine such as those produced by Pfizer and Moderna.
It said that in the general population, effectiveness against infection after seven months remained at 89%, while against hospitalisation and death, this time six months after the second dose, it remained at 96% and 99% respectively.
The findings on protection from infection differ from a study carried out by Pfizer and published on Oct. 4 in the Lancet medical journal.
That showed the effectiveness of the Pfizer/BioNTech vaccine in preventing infection dropped to 47% from 88% six months after the second dose.
The ISS study did not make reference to the study in the Lancet, which focused on electronic health records of 3.4 million members of a U.S. healthcare provider, but did not include data on adherence to mask guidelines and occupation, which could have affected testing frequency and exposure.
In Italy, people are obliged to wear masks indoors and they had been required outdoors before the summer, and stringent behavioural rules have been in place, which may have influenced the results.
The ISS report said that immunocompromised people saw their protection against infection drop from 28 days after the second dose, with the reduction varying widely according to which diseases cause the weakened immune system.
In people with co-morbidities but who are not necessarily immunodepressed, the study reported a reduction in protection from infection which declined from 75% 28 days after the second dose to 52% after about seven months.
Efficacy among people over the age of 80 and nursing home residents also decreased slightly but remained above 80%, the ISS said.
Comparing the period in which the Alpha variant was prevalent with that in which the Delta variant was, efficacy against infection fell from 84.8% to 67.1%, while protection against hospitalisation declined much less, from 91.7% to 88.7%.
The Institute's reports are among the material the Italian government takes into account for its health decisions. Rome must consider in the coming weeks whether to extend a third vaccine dose to the whole population.
To date, the third dose, which started on Sept. 20, has only been given to immunocompromised patients, over-80s, nursing home residents and operators, and health workers over 60 or with comorbidities or other factors leading to increased exposure to possible infection.
The European Union's drugs regulator EMA said on Oct. 4 that people with weakened immune systems should get a third dose of a COVID-19 vaccine from Pfizer-BioNTech or Moderna, but left it to member states to decide if the wider population should have a booster.
(Reporting by Emilio Parodi, Editing by Gavin Jones and Alison Williams)