Search

Background Evidence is limited for influenza vaccine effectiveness (VE) against laboratory-confirmed influenza among young children. Using test-negative design (a modified case-control study) which minimizes confounding by health care-seeking behavior and misclassification of diseases, we aimed to monitor influenza VE among young children in Japan where all approved influenza vaccines are egg-propagated, inactivated formulations (IIV). Methods For seasons spanning 2013-14 to 2017-18 in Osaka and Fukuoka Prefectures, Japan, we employed prospective, active, and systematic recruitment of children aged Results We analyzed 4,614 subjects including 1,917 cases. VEs of IIV with 2 doses approximated 50%, ranging from 41% (95% confidence interval [CI]: 14 % to 60%) in 2016-17 season to 63% (95% CI: 45% to 76%) in 2017-18 season. Significant VEs were also shown for predominant circulating strains every season, irrespective of their antigenic match to vaccine strains (56% and 65% for A[H1N1]pdm, 37% and 50% for A[H3N2], and 60% for B[Yamagata]). Conclusions IIV provided modest and significant protection against laboratory-confirmed influenza in young Japanese children. Key messages Test-negative design is useful for monitoring influenza VE.

The recent increase in macrolide-resistant Mycoplasma pneumoniae (M. pneumoniae) in Asia has become a continuing problem. A point-of-care testing method that can quickly detect M. pneumoniae and macrolide-resistant mutations (MR mutations) is critical to proper antimicrobial use. Smart Gene TM (MIZUHO MEDY Co., Ltd. Tosu-City, Saga, Japan) is a compact and inexpensive fully automatic gene analyzer that combines amplification with polymerase chain reaction (PCR) and the quenching probe method to specify the gene and MR mutations simultaneously. We performed a clinical evaluation of this device and its reagents on pediatric patients with M. pneumoniae -suspected respiratory infections and evaluated the impact of the assay on antimicrobial selection. Using real-time PCR as a comparison control, the sensitivity of Smart Gene TM was 97.8% (44/45), its specificity was 93.3% (98/105) and its overall concordance rate was 94.7% (142/150). The overall concordance rate of Smart Gene TM diagnosis of MR mutations in comparison with sequence analysis was 100% (48/48). The ratio of MR mutations was significantly higher at high-level medical institutions than at a primary medical clinic (P = 0.023), and changes in antibiotic therapy to drugs other than macrolides was significantly more common in patients with MR mutations (P = 0.00024). Smart Gene TM demonstrated excellent utility in the diagnosis of M. pneumoniae and the selection of appropriate antimicrobials for MR mutations at primary medical institutions, which play a central role in community-acquired pneumonia care. The use of this device may reduce referrals to high-level medical institutions for respiratory infections, thereby reducing the medical and economic burden on patients.

Supplemental Digital Content is available in the text., Background: A granule formulation of baloxavir marboxil, a selective inhibitor of influenza cap-dependent endonuclease, was newly developed for children with difficulty swallowing tablets. Methods: A multicenter open-label study was conducted during the 2017–2018 influenza season to assess the safety, pharmacokinetics and clinical/virologic outcomes of single, oral, weight-based doses of baloxavir granules in Japanese children infected with influenza virus. The primary clinical endpoint was the time to illness alleviation of influenza. Results: All 33 enrolled children completed the study and received baloxavir (1 mg/kg for 12 children weighing 4-log decrease in infectious viral titer occurred on day 2 and a temporary 2-log increase on day 4. Polymerase acidic protein/I38T/M-substituted viruses were detected in 5 children infected with influenza A, but none with influenza B. Conclusions: Baloxavir granules and the weight-based dose regimen were considered to be well tolerated in children, with rapid influenza virus reduction and associated symptom alleviation. Evidence of baloxavir activity against influenza B was observed, but further data are required for confirmation.

We have evaluated a new immunochromatographic kit, "KBM LineCheck Flu AB", which had been developed for enhanced detection of influenza B viruses. Five strains of influenza A and B viruses were tested for reactivity and detection limits of the kit. Compared with the detection limits of commercially available kit of QuickNavi-Flu, "KBM LineCheck Flu AB" showed a nearly equal reactivity to influenza A viruses, but quadruple reactivity to 2 influenza B viruses. Also, "KBM LineCheck Flu AB" exhibited high specificity when tested in 130 influenza-negative culture specimens derived from 24 adult volunteers. Furthermore, "KBM LineCheck Flu AB" was clinically evaluated by using 866 specimens, including 190 nasal swabs, 201 nasal aspirations, 262 self-blown nasal discharges, and 213 pharyngeal swabs. Compared with the results of QuickNavi-Flu for influenza A, the test efficiency for the nasal swabs, the nasal aspirations, self-blown nasal discharges, and pharyngeal swabs were calculated to be 95.8%, 92.0%, 95.0%, and 94.8%, respectively. Whereas, as to influenza B, the test efficiency for the nasal swabs, the nasal aspirations, self-blown nasal discharges, and pharyngeal swabs was calculated to be 96.3%, 98.5%, 96.2%, and 93.4%, respectively. Similarly, compared with the results of influenza A viral culture, the test efficiency for the nasal swabs, the nasal aspirations, self-blown nasal discharges, and pharyngeal swabs was calculated to be 95.3%, 91.0%, 93.9%, and 92.5%, respectively. Regarding influenza B culture, the test efficiency for the nasal swabs, the nasal aspirations, self-blown nasal discharges, and pharyngeal swabs were calculated to be 95.8%, 97.5%, 95.1%, 91.5%, respectively. Overall, we concluded that the "KBM LineCheck Flu AB" is useful and suitable for diagnosis of influenza A and especially influenza B.

In Japan, the routine immunization program with oral polio vaccine (OPV) has been suspended since September 2012, when a program with 4 doses of inactivated monovalent polio vaccine (IPV) or quadrivalent vaccine against diphtheria, pertussis, and tetanus with IPV (DTaP-IPV) was introduced. The aim of this study was to examine the interchangeability among these 3 types of polio vaccines.We conducted a prospective cohort study at 5 pediatric clinics in Japan. A total of 153 infants were assigned to 1 of the 4 groups by considering the vaccination history of OPV and trivalent vaccine against DTaP. Eleven infants with a history of OPV received 3 doses of DTaP-IPV; 49 infants with a history of OPV and DTaP received 3 doses of IPV; 50 polio vaccine-naive infants received 2 doses of IPV followed by 2 doses of DTaP-IPV; and 43 polio vaccine-naive infants received 2 doses of DTaP-IPV followed by IPV. The immunogenicity after polio vaccination was evaluated among these 4 groups.After 2 doses of polio vaccination, more than 80% of the infants exhibited a neutralization antibody titer ≥1:8 for all Sabin strains and wild strains in all groups. After the third dose, the seroprotection proportion (i.e., a neutralization antibody titer ≥1:8) reached about 100%. After the fourth dose, a neutralization antibody titer exceeded the required protective levels (i.e., a neutralization antibody titer ≥1:8) considerably in all groups.Four doses of polio vaccines induced a sufficient level of immunity in Japanese infants, irrespective of vaccine combinations or order.