TRENDS IN INVASIVE PNEUMOCOCCAL DISEASE (IPD) IN ADULTS OF 65 YEARS OR OVER, ITALY, 2012-2017
The paediatric heptavalent pneumococcal conjugate vaccine (PCV7) was licensed in 2001 and added to the National Immunisation Programme (NIP) in 2005. The 13-valent conjugate vaccine (PCV13) entered the paediatric NIP in 2012. PCV13 adult vaccination started in 2012 for at-risk population in some regions and introduced in NIP in 2017 sequentially with the 23-valent polysaccharide (PPV23), used before in at-risk and older people.
Cases were reported through the European Centre for Disease Prevention and Control surveillance system. IPD serotype specific counts were aggregated into PCV13-, PCV13 non-PCV7-, 20-valent conjugate vaccine (PCV20) non-PCV13-, PPV23-, and PPV23 non-PCV13-type groups. The percentage change in annual number of cases was estimated using linear regression analysis of the log of annual number of cases.
During 2012-17, there was an average annual increase of 34% for PCV20 non-PCV13- (95%CI 20.4 to 48.8; p=0.002), of 16% for PPV23- (95%CI 7.5 to 25.1; p=0.006), and of 31.5% for PPV23 non-PCV13- (95%CI 18.1 to 46.4; p=0.002)-, without significant changes in PCV13-, PCV13 non-PCV7-type groups
Implementation of the paediatric PCV13 programme, despite high coverage, does not appear to be associated with changes in PCV13-type IPD in adults. Reductions may be achieved with direct immunisation with PCV13 or next-generation vaccine (PCV20)