Use of the 7-valent pneumococcal conjugate vaccine (PCV7) may have had a part in reducing the incidence of severe middle ear inflammation of acute otitis media (AOM) in Japanese children, decreasing the rate of myringotomies for AOM, said Atsushi Sasaki, of the Hiroshima (Japan) University, and associates.

To assess whether use of PCV7 and then PCV13 affected AOM incidence, the investigators looked at the incidence of visits to medical institutions (VtMI) due to all-cause AOM in children younger than 15 years in the Japan Medical Data Center Claims Database between January 2005 and December 2015. Data for children aged 10 years to younger than 15 years served as the control. The rate of myringotomies for AOM (MyfA) from January 2007 to December 2015 also was assessed.

After the introduction of PCVs, no age groups younger than 5 years showed any significant decline in the incidence of VtMI due to AOM, compared with the 6 years prior to PCV introduction. However, after the PCVs were paid for by public funds in 2011, a reduction in the rates of MyfA was seen across all age groups. Within 2 years, there were significant declines in the rates of MyfA for 1- and 5-year-olds.

Numerous other studies have “concluded that the preventive effect of PCV7 against AOM was very modest,” the researchers said. “In contrast, our study proposes the hypothesis that PCV7 use in 1-year-olds may contribute to the decreased incidence of severe middle ear inflammation of AOM. When evaluating the effectiveness of PCV, measures to evaluate severity may be as important as evaluating disease prevention.”

Read more in Auris Nasus Larynx (2017 Nov 1. doi: 10.1016/j.anl.2017.10.006 ).