Recombinant or Standard-Dose Influenza Vaccine in Adults under 65 Years of Age.

BACKGROUND: Quadrivalent recombinant influenza vaccines contain three times the amount of hemagglutinin protein as standard-dose egg-based vaccines, and the recombinant formulation is not susceptible to antigenic drift during manufacturing. Data are needed on the relative effectiveness of recombinant vaccines as compared with standard-dose vaccines against influenza-related outcomes in adults under the age of 65 years. METHODS: In this cluster-randomized observational study, Kaiser Permanente Northern California facilities routinely administered either a high-dose recombinant influenza vaccine (Flublok Quadrivalent) or one of two standard-dose influenza vaccines during the 2018-2019 and 2019-2020 influenza seasons to adults 50 to 64 years of age (primary age group) and 18 to 49 years of age. Each facility alternated weekly between the two vaccine formulations. The primary outcome was influenza (A or B) confirmed by polymerase-chain-reaction (PCR) testing. Secondary outcomes included influenza A, influenza B, and influenza-related hospitalization outcomes. We used Cox regression analysis to estimate the hazard ratio of the recombinant vaccine as compared with the standard-dose vaccines against each outcome. We calculated the relative vaccine effectiveness as 1 minus the hazard ratio. RESULTS: The study population included 1,630,328 vaccinees between the ages of 18 and 64 years (632,962 in the recombinant-vaccine group and 997,366 in the standard-dose group). During this study period, 1386 cases of PCR-confirmed influenza were diagnosed in the recombinant-vaccine group and 2435 cases in the standard-dose group. Among the participants who were 50 to 64 years of age, 559 participants (2.00 cases per 1000) tested positive for influenza in the recombinant-vaccine group as compared with 925 participants (2.34 cases per 1000) in the standard-dose group (relative vaccine effectiveness, 15.3%; 95% confidence interval [CI], 5.9 to 23.8; P = 0.002). In the same age group, the relative vaccine effectiveness against influenza A was 15.7% (95% CI, 6.0 to 24.5; P = 0.002). The recombinant vaccine was not significantly more protective against influenza-related hospitalization than were the standard-dose vaccines. CONCLUSIONS: The high-dose recombinant vaccine conferred more protection against PCR-confirmed influenza than an egg-based standard-dose vaccine among adults between the ages of 50 and 64 years. (Funded by Sanofi; ClinicalTrials.gov number, NCT03694392.).

Safety of 9-valent human papillomavirus vaccine administered to males and females in routine use.

BACKGROUND: The nine-valent human papillomavirus vaccine (HPV9, Gardasil®9) was licensed in the USA in December 2014. This study was a multiyear post-licensure study to assess HPV9 safety following routine administration. METHODS: This retrospective cohort study compared the risk of emergency department visits and hospitalizations during the interval soon after vaccination with risk during a later interval. Kaiser Permanente Northern California (KPNC) members aged ≥ 9 years who received ≥ 1 HPV9 dose between 10/1/2015-9/30/2017 were included. Outcomes were grouped into predefined diagnostic categories. We compared the odds of events in postvaccination risk intervals (days 0-14, days 1-60) with odds of events during control intervals (days 61-75, days 61-120) using conditional logistic regression. We characterized prespecified events on the day of vaccination (allergic reaction and syncope) and all deaths in the study period. RESULTS: The study included 215,965 individuals receiving ≥ 1 dose of HPV9, of whom 140,628 had no prior HPV vaccination. We observed similar numbers of males and females and racial/ethnic diversity consistent with the underlying population. At first dose median age was 12-13 years and 77% received ≥ 1 concomitant vaccine. Eighteen event categories were significantly elevated, including skin disorders (odds ratio [OR] 1.88, 95% confidence interval [CI] 1.00, 3.53) and ill-defined conditions (OR 1.36, 95% CI 1.13, 1.64; category includes abdominal pain, allergic reactions, syncope, etc.). On review, most findings were previously known, preceded vaccination, or had other causes. Allergic reactions and syncope at vaccination were infrequent but many were potentially related. No deaths (n = 37) were considered related to HPV9 and were consistent with the background rate. CONCLUSIONS: We did not identify new safety concerns related to HPV9. The results are consistent with the HPV9 safety profile as established from previous studies/surveillance. REGISTRATION: European Network of Centres for Pharmacoepidemiology and Pharmacovigilance (EUPAS13151, protocol V503-028).

Impact of the 13-Valent Pneumococcal Conjugate Vaccine on Invasive Pneumococcal Disease After Introduction Into Routine Pediatric Use.

BACKGROUND: In 2010, the 13-valent pneumococcal conjugate vaccine (PCV13) replaced 7-valent PCV (PCV7) for protection against invasive pneumococcal disease (IPD). This study used laboratory surveillance data to examine the effect of PCV13 on IPD before and after PCV13 introduction among children aged 6 weeks to <6 years and those aged ≥6 weeks. METHODS: Observational laboratory-based IPD surveillance data were compared for the periods May 2010-April 2018 and May 2008-April 2010 (the PCV7 period) using a database of Kaiser Permanente Northern California (KPNC) members with laboratory-confirmed IPD. RESULTS: Among children aged 6 weeks to 6 years, overall IPD incidence decreased from 11.57 per 100 000 during the PCV7 period to 4.09 per 100 000 after PCV13 introduction; PCV13-type IPD incidence decreased from 5.12 to 0.84 per 100 000. Non-PCV13-serotype IPD did not change significantly in this age group (PCV7 period, 1.71 per 100 000 and after PCV13, 2.52 per 100 000). Of cases occurring in this group, bacteremia was the most common clinical diagnosis. Across all ages, IPD decreased from 9.49 to 6.23 per 100 000 and PCV13-type IPD decreased from 4.67 to 1.89 per 100 000, changes being mostly due to decreases in serotypes 19A and 7F. IPD caused by non-PCV13 serotypes did not change (3.34 and 3.35 per 100 000). Overall, pneumococci isolated after PCV13 introduction had increased susceptibility to penicillin, cefotaxime, and ceftriaxone.This prospective, laboratory-based surveillance study in Kaiser Permanente Northern California members examined annual IPD incidence before and after PCV13 introduction. In children aged 6 weeks to <6 years, IPD caused by PCV13 serotypes decreased significantly (84%) during the surveillance period. CONCLUSIONS: IPD incidence decreased further in every age group after PCV13 introduction, suggesting both direct vaccination effects in the infant population and indirect effects in adults. CLINICAL TRIALS REGISTRATION: NCT01128439.

Evaluation of a Vaccine-Communication Tool for Physicians.

OBJECTIVES: To evaluate a Kaiser Permanente Northern California physician training tool entitled "Effective Communication without Confrontation" aimed at improving communication with vaccine-hesitant parents, building trust, and alleviating physician stress surrounding vaccination visits. STUDY DESIGN: Trainings were held May to July 2015. Pre- and post-training surveys assessed physician comfort and perceived effectiveness in communicating with vaccine-hesitant parents. We measured vaccination coverage at the 2-, 4-, and 6-month well-child visits, and days undervaccinated at 9 months of age. We compared vaccination rates before and after the training. RESULTS: Of 415 physicians who received training, 249 completed post-training surveys. Physicians reported that the training helped them feel "much more or more" comfortable talking with parents who are unsure (72.3%), want to delay (73.9%), or refuse (63.5%) vaccinations and "much more or more" effective at persuading parents who are unsure (67.5%) or want to delay vaccinations (61.4%). They reported feeling "the same or less" effective persuading parents who refuse vaccinations (66.3%). Vaccine coverage remained unchanged and high from before to after the training (95%-96%), as did parent satisfaction with his or her child's provider (4.73/5.00). CONCLUSIONS: The Effective Communication without Confrontation training did not increase vaccine coverage, but did improve physicians' comfort and perceived effectiveness communicating with most vaccine-hesitant parents and may help to ease potentially stressful vaccination visits.

Retrospective study of the use of an influenza disease two-tiered classification system to characterize clinical severity in US children.

In children <5 years, influenza is associated with higher risk of serious disease and hospitalization when compared with other age groups. Influenza vaccination reduces the risk of influenza and vaccination may attenuate the severity of disease. Recent studies in Europe suggest that classifying influenza disease as mild versus moderate-to-severe (M-S) using a novel definition may be clinically significant. We retrospectively evaluated whether this M-S definition also characterized influenza severity in a cohort of US children. We included children <18 years at Kaiser Permanente Northern California with PCR-confirmed influenza during the 2013-2014 influenza season. We classified children as M-S if they had ≥1 symptom: fever >39°C, acute otitis media, lower respiratory tract infection (LRTI), or extra-pulmonary complications; otherwise, they were classified as mild. We used multivariable log-binomial models to assess whether M-S influenza disease was associated with increased healthcare utilization. Nearly half of the 1,105 influenza positive children were classified as M-S. Children 6-35 months had the highest proportion of M-S disease (35.1%), mostly due to LRTI (63.2%) and fever (44.6%). Children ≥6 months who had M-S disease were associated with a 1.6 to 2.8 times increased likelihood of having had an emergency department or any follow-up outpatient visits. Those who had M-S disease were associated with an increased likelihood of receiving antibiotics, with the highest likelihood in children 6-35 months (RR 9.0, 95% CI 4.1, 19.8). While more studies are needed, an influenza classification system may distinguish children with more clinically significant disease.

Invasive Pneumococcal Disease Among HIV-Infected and HIV-Uninfected Adults in a Large Integrated Healthcare System.

It is unclear whether HIV-infected individuals remain at higher risk of invasive pneumococcal disease (IPD) compared with HIV-uninfected individuals. We conducted a cohort study of HIV-infected and demographically matched HIV-uninfected adults within Kaiser Permanente Northern California during the period 1996-2011. We used Poisson models to obtain rate ratios (RRs) for incident IPD associated with HIV infection and other risk factors. Among 13,079 HIV-infected and 137,643 HIV-uninfected adults, the IPD rate per 100,000 person-years was 160 (n = 109 events) for HIV-infected and 8 (n = 75 events) for HIV-uninfected subjects, with an adjusted RR of 13.0 [95% confidence interval (CI): 9.1-18.7]. For HIV-infected individuals, IPD incidence per 100,000 person-years decreased by 71% during study follow-up, from 305 in 1996-1999 to 88 in 2010-2011 (p < 0.001), with an adjusted RR of 6.6 (95% CI: 2.7-16.1) compared with HIV-uninfected subjects in 2010-2011. Risk factors for IPD among HIV-infected individuals included black compared with white race/ethnicity, smoking, cancer, and higher HIV RNA levels. The 23-valent pneumococcal polysaccharide vaccination was not associated with a reduced risk of IPD in HIV-infected or HIV-uninfected individuals. Among HIV-infected IPD cases, the most common serotype was 19A (33%), and 59% of serotypes were covered by the 13-valent pneumococcal conjugate vaccine (PCV13). Despite a dramatic decline in IPD incidence for HIV-infected adults since 1996, IPD rates were nearly sevenfold higher compared with HIV-uninfected adults in recent years, even after adjustment for risk factors. Timely antiretroviral therapy initiation, risk reduction strategies, and recent guidelines recommending PCV13 use may further reduce IPD incidence among HIV patients.

Risk of underlying chronic medical conditions for invasive pneumococcal disease in adults.

PURPOSE: In the United States, the 13-valent pneumococcal conjugate vaccine is recommended in persons ⩾65years of age, and persons ⩽65years of age with immunocompromising (IC) conditions. For invasive pneumococcal disease (IPD) prevention in those ⩽65 with non-IC medical conditions, the 23-valent polysaccharide vaccine is recommended. This group is at higher risk of IPD than the general population, but the level of risk is not well-quantified. We estimated IPD risk by individual underlying medical conditions, and by total number of conditions, for persons ⩾18years of age. We calculated the relative risks (RR) of various medical conditions, comparing the incident IPD cases to the general study population, and used Poisson regression models to estimate an IPD RR, adjusting for other conditions. We also examined IPD incidence by number of conditions diagnosed in each calendar year, using a risk-stacking model. RESULTS: Underlying medical conditions with the highest adjusted RR for IPD were chronic liver disease (RR 2.1, 95% CI 1.5-2.8) and chronic obstructive pulmonary disease (COPD; RR 2.1, 95% CI 1.8-2.5). IPD risk increased with increasing number of medical conditions: adjusted RR, 2.2 (95% CI 1.9-2.5) 1 condition, 2.9 (2.5-3.5) for 2 conditions, and 5.2 (4.4-6.1) for 3 conditions. CONCLUSIONS: For persons with a single, non-IC medical condition, IPD risk was twice that for the general KPNC population. Persons with multiple, non-IC chronic conditions exhibited increased IPD risk with each additional condition. Such information may inform discussions on recommendations for adult pneumococcal immunization and prevention.