Randomized comparison of the safety of Flublok(®) versus licensed inactivated influenza vaccine in healthy, medically stable adults ≥ 50 years of age

Preliminary findings from the Dynamics of the Immune Responses to Repeat Influenza Vaccination Exposures (DRIVE I) Study: a Randomized Controlled Trial

Background

Studies have reported that repeated annual vaccination may influence the effectiveness of the influenza vaccination in the current season. The mechanisms underlying these differences are unclear but might include "focusing" of the adaptive immune response to older strains.

Methods

We established a 5-year randomized placebo-controlled trial of repeated influenza vaccination (Flublok, Sanofi Pasteur) in adults 18-45 years of age. Participants were randomized equally between five groups, with planned annual receipt of vaccination (V) or saline placebo (P) as follows: P-P-P-P-V, P-P-P-V-V, P-P-V-V-V, P-V-V-V-V, or V-V-V-V-V. Serum samples were collected each year just before vaccination and after 30 and 182 days. A subset of sera were tested by hemagglutination inhibition assays, focus reduction neutralization tests and enzyme-linked immunosorbent assays against vaccine strains.

Results

From 23 October 2020 through 11 March 2021 we enrolled and randomized 447 adults. We selected sera from 95 participants at five timepoints from the first two study years for testing. Among vaccinated individuals, antibody titers increased between days 0 and 30 against each of the vaccine strains, with substantial increases for first-time vaccinees and smaller increases for repeat vaccinees, who had higher pre-vaccination titers in year 2. There were statistically significant reductions in the proportion of participants achieving a four-fold greater rise in antibody titer for the repeat vaccinees for A(H1N1), B/Victoria and B/Yamagata, but not for influenza A(H3N2). There were no statistically significant differences between groups in geometric mean titers at day 30 or the proportions of participants with antibody titers ≥40 at day 30 for any of the vaccine strains.

Conclusions

In the first two years, repeat vaccinees and first-time vaccinees had similar post-vaccination geometric mean titers to all four vaccine strains, indicative of similar levels of clinical protection. The vaccine strains of A(H1N1) and A(H3N2) were updated in year 2, providing an opportunity to explore antigenic distances between those strains in humans in subsequent years.

Trivalent and quadrivalent seasonal influenza vaccine in adults aged 60 and older: a systematic review and network meta-analysis

OBJECTIVES

To compare the efficacy of influenza vaccines of any valency for adults 60 years and older.

DESIGN AND SETTING

Systematic review with network meta-analysis (NMA) of randomised controlled trials (RCTs). MEDLINE, EMBASE, JBI Evidence-Based Practice (EBP) Database, PsycINFO, and Cochrane Evidence -Based Medicine database were searched from inception to 20 June 20, 2022. Two reviewers screened, abstracted, and appraised articles (Cochrane Risk of Bias (ROB) 2.0 tool) independently. We assessed certainty of findings using Confidence in Network Meta-Analysis and Grading of Recommendations, Assessment, Development and Evaluations approaches. We performed random-effects meta-analysis and network meta-analysis (NMA), and estimated odds ratios (ORs) for dichotomous outcomes and incidence rate ratios (IRRs) for count outcomes along with their corresponding 95% confidence intervals (CIs) and prediction intervals.

PARTICIPANTS

Older adults (≥60 years old) receiving an influenza vaccine licensed in Canada or the USA (vs placebo, no vaccine, or any other licensed vaccine), at any dose.

MAIN OUTCOME MEASURES

Laboratory-confirmed influenza (LCI) and influenza-like illness (ILI). Secondary outcomes were the number of vascular adverse events, hospitalisation for acute respiratory infection (ARI) and ILI, inpatient hospitalisation, emergency room (ER) visit for ILI, outpatient visit, and mortality, among others.

RESULTS

We included 41 RCTs and 15 companion reports comprising 8 vaccine types and 206 032 participants. Vaccines may prevent LCI compared with placebo, with high-dose trivalent inactivated influenza vaccine (IIV3-HD) (NMA: 9 RCTs, 52 202 participants, OR 0.23, 95% confidence interval (CI) (0.11 to 0.51), low certainty of evidence) and recombinant influenza vaccine (RIV) (OR 0.25, 95%CI (0.08 to 0.73), low certainty of evidence) among the most efficacious vaccines. Standard dose trivalent IIV3 (IIV3-SD) may prevent ILI compared with placebo, but the result was imprecise (meta-analysis: 2 RCTs, 854 participants, OR 0.39, 95%CI (0.15 to 1.02), low certainty of evidence). Any HD was associated with prevention of ILI compared with placebo (NMA: 9 RCTs, 65 658 participants, OR 0.38, 95%CI (0.15 to 0.93)). Adjuvanted quadrivalent IIV (IIV4-Adj) may be associated with the least vascular adverse events, but the results were very uncertain (NMA: eight 8 RCTs, 57 677 participants, IRR 0.18, 95%CI (0.07 to 0.43), very low certainty of evidence). RIV on all-cause mortality may be comparable to placebo (NMA: 20 RCTs, 140 577 participants, OR 1.01, 95%CI (0.23 to 4.49), low certainty of evidence).

CONCLUSIONS

This systematic review demonstrated efficacy associated with IIV3-HD and RIV vaccines in protecting older persons against LCI. RIV vaccine may reduce all-cause mortality when compared with other vaccines, but the evidence is uncertain. Differences in efficacy between influenza vaccines remain uncertain with very low to moderate certainty of evidence.

PROSPERO REGISTRATION NUMBER

CRD42020177357.

Immunogenicity and safety of a quadrivalent recombinant influenza vaccine manufactured in Iran (FluGuard) in volunteers aged 18-60 years: A double-blind, non-inferiority, randomized controlled trial

BACKGROUND

This study aimed to evaluate the non-inferiority of the FluGuard (a quadrivalent recombinant vaccine manufactured by Nivad Pharmed Salamat Company in Iran) by comparing its immunogenicity and safety with Vaxigrip Tetra (a quadrivalent inactivated vaccine manufactured by Sanofi Pasteur in France).

MATERIALS AND METHODS

In this double-blind, randomized controlled trial, eligible volunteers aged 18-60 were randomized to receive either FluGuard or Vaxigrip Tetra vaccines. Immunogenicity was evaluated using the Hemagglutination Inhibition (HAI) assay and reported with the geometric mean titer (GMT), seroprotection, and seroconversion. In addition, vaccine safety was assessed by interviewing participants through phone calls.

RESULTS

Out of 110 randomized volunteers, 51 and 53 were entered into the final analysis in the Vaxigrip and FluGuard groups, respectively. Vaxigrip had a higher seroprotection rate for the H1N1 strain compared with FluGuard (98 % vs. 91 %). Besides, FluGuard had higher seroprotection rates for H3N2 (74 % vs. 69 %), B-Yamagata (87 % vs. 84 %), and B-Victoria (66 % vs. 41 %) strains compared with Vaxigrip. In all four strains, FluGuard was non-inferior to Vaxigrip with the upper bounds of the 95 % CI on the ratio of the GMTs < 1.5: H1N1 (1.25), H3N2 (0.94), B-Yamagata (0.62), and B-Victoria (0.59). Furthermore, FluGuard was non-inferior to Vaxigrip with the upper bounds of the 95 % CI on the difference between the seroconversion rates < 10 %: H1N1 (2 %), H3N2 (10 %), B-Yamagata (-10 %), and B-Victoria (-29 %). The prevalence of solicited adverse drug reactions did not differ between groups. Furthermore, participants did not experience serious adverse events.

CONCLUSION

Our findings support the non-inferiority of the FluGuard vaccine to the Vaxigrip vaccine regarding immunogenicity and safety.

CLINICAL TRIAL REGISTRY

The study protocol was approved by the Iranian Registry of Clinical Trials (IRCT20210901052358N5).

Systematic review of the efficacy, effectiveness and safety of high-dose seasonal influenza vaccines for the prevention of laboratory-confirmed influenza in individuals ≥18 years of age

This review sought to assess the efficacy, effectiveness and safety of high-dose inactivated influenza vaccines (HD-IIV) for the prevention of laboratory-confirmed influenza in individuals aged 18 years or older. A systematic literature search was conducted in electronic databases and grey literature sources up to 7 February 2020. Randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs) were included. The search returned 28,846 records, of which 36 studies were included. HD-IIV was shown to have higher relative vaccine efficacy in preventing influenza compared with standard-dose influenza vaccines (SD-IIV3) in older adults (Vaccine effectiveness (VE) = 24%, 95% CI 10-37, one RCT). One NRSI demonstrated significant effect for HD-IIV3 against influenza B (VE = 89%, 95% CI 47-100), but not for influenza A(H3N2) (VE = 22%, 95% CI -82 to 66) when compared with no vaccination in older adults. HD-IIV3 showed significant relative effect compared with SD-IIV3 for influenza-related hospitalisation (VE = 11.8%, 95% CI 6.4-17.0, two NRSIs), influenza- or pneumonia-related hospitalisation (VE = 13.7%, 95% CI 9.5-17.7, three NRSIs), influenza-related hospital encounters (VE = 13.1%, 95% CI 8.4-17.7, five NRSIs), and influenza-related office visits (VE = 3.5%, 95% CI 1.5-5.5, two NRSIs). For safety, HD-IIV were associated with significantly higher rates of local and systemic adverse events compared with SD-IIV (combined local reactions, pain at injection site, swelling, induration, headache, chills and malaise). From limited data, compared with SD-IIV, HD-IIV were found to be more effective in the prevention of laboratory-confirmed influenza, for a range of proxy outcome measures, and associated with more adverse events.

Systematic review of the efficacy, effectiveness and safety of recombinant haemagglutinin seasonal influenza vaccines for the prevention of laboratory-confirmed influenza in individuals ≥18 years of age

The most effective means of preventing seasonal influenza is through vaccination. In this systematic review, we investigated the efficacy, effectiveness and safety of recombinant haemagglutinin (HA) seasonal influenza vaccines to prevent laboratory-confirmed influenza. A systematic literature search was conducted in electronic databases and grey literature sources up to 7 February 2020. Randomised controlled trials and non-randomised studies of interventions were eligible for inclusion. The search returned 28,846 records, of which 10 studies on recombinant HA influenza vaccine met our inclusion criteria. One study found that the quadrivalent recombinant HA influenza vaccine had higher relative vaccine efficacy (rVE) in preventing laboratory-confirmed influenza during the 2014-15 season compared with traditional quadrivalent vaccination in adults aged ≥50 years (rVE = 30%, 95% CI 10%-47%, moderate-certainty evidence). In a subgroup analysis, higher rVE was reported for influenza A (rVE = 36%, 95% CI 14% to 53%), but not for B (non-significant). Another study reported higher efficacy for the trivalent recombinant HA vaccine compared with placebo (VE = 45%, 95% CI 19-63, 1 RCT, low-certainty evidence) in adults aged 18-55 years. With the exception of a higher rate of chills (RR = 1.33, 95% CI 1.03-1.72), the safety profile of recombinant HA vaccines was comparable to that of traditional influenza vaccines. The evidence base for the efficacy and effectiveness of recombinant HA influenza vaccines is limited at present, although one study found that the quadrivalent recombinant HA influenza vaccine had higher rVE compared with traditional quadrivalent vaccination in adults aged ≥50 years.

Design of the Recombinant Influenza Neuraminidase Antigen Is Crucial for Its Biochemical Properties and Protective Efficacy

Supplementing influenza vaccines with recombinant neuraminidase (rNA) antigens remains a promising approach for improving suboptimal vaccine efficacy. However, correlations among rNA designs, properties, and protection have not been systematically investigated. Here, we performed a comparative analysis of several rNAs produced by the baculovirus/insect cell system. The rNAs were designed with different tetramerization motifs and NA domains from a recent H1N1 vaccine strain (A/Brisbane/02/2018) and compared for enzymatic properties, antigenicity, stability, and protection in mice. We found that the enzymatic properties differ between rNAs containing the NA head domain versus the full ectodomain, the formation of higher-order rNA oligomers is tetramerization domain dependent, whereas the protective efficacy is more contingent on the combination of the tetramerization and NA domains. Following single-dose immunizations, an rNA possessing the full ectodomain and the tetramerization motif from the human vasodilator-stimulated phosphoprotein provided much better protection than an rNA with ∼10-fold more enzymatically active molecules that is comprised of the head domain and the same tetramerization motif. In contrast, these two rNA designs provided comparable protection when the tetramerization motif from the tetrabrachion protein was used instead. These findings demonstrate that individual rNAs should be thoroughly evaluated for vaccine development, as the heterologous domain combination can result in rNAs with similar key attributes that vastly differ in protection. IMPORTANCE For several decades, it has been proposed that influenza vaccines could be supplemented with recombinant neuraminidase (rNA) to improve efficacy. However, some key questions for manufacturing stable and immunogenic rNAs remain to be answered. We show here that the tetramerization motifs and NA domains included in the rNA construct design can have a profound impact on the biochemical, immunogenic, and protective properties. We also show that the single-dose immunization regimen is more informative for assessing the rNA immune response and protective efficacy, which is surprisingly more dependent on the specific combination of NA and tetramerization domains than common attributes for evaluating NA. Our findings may help to optimize the design of rNAs that can be used to improve or develop influenza vaccines.

Diagnosis and management of hypersensitivity reactions to vaccines

INTRODUCTION

Many countries in Europe now recommend and enforce mandatory vaccinations to improve vaccination coverage. Thus, the number of adverse events following immunization (AEFI) may show an increase. Among these events, severe hypersensitivity reactions to vaccines are rare. However, it is important that they be identified and recognized so that they may be adequately managed.

AREAS COVERED

The literature search was undertaken through PubMed and Embase to identify English-language papers focusing on hypersensitivity to vaccines.

EXPERT OPINION

Hypersensitivity reactions following vaccinations are rare and are classified according to their chronology and extension: immediate when they occur within the first 4 hours following administration and non-immediate when they occur later. Local reactions are the most common adverse event following injection of vaccines and generally do not require any allergy workup. Immediate reactions, however, are potentially IgE-mediated and require an allergy workup. In general, a previously known food allergy (i.e., egg or milk) is not a contraindication to immunizations. Patients with a known allergy to gelatin, yeast, latex, antibiotics, or other specific components of vaccines require an allergy workup before administration of the vaccine.

Results of Influenza Vaccination: Short Follow-Up Study of a Turkish Population

INTRODUCTION:

The trivalent inactivated influenza vaccine was approved for use in Turkey during the 2018-2019 influenza season. We evaluated beliefs regarding the vaccine and vaccination outcomes in a Turkish population.

METHODS:

Individuals who were vaccinated with the trivalent inactivated influenza vaccine between November 1 and December 31, 2018, at the Sisli Hamidiye Training and Research Hospital in Istanbul, Turkey, were included in this study. A 15-item questionnaire was completed by a physician during a face-to-face interview with the participants. All participants were followed during the 2018-2019 influenza season through May 2019. The participants were instructed to consult the same physician in case of sudden illness. Participants’ beliefs and outcomes were assessed by their vaccination status for the 2017-2018 influenza season.

RESULTS:

A total of 150 participants were recruited. Their median age was 66 (range, 22-88) years. During the 2017-2018 influenza season, 4.1% had been hospitalized, 53.5% had developed an upper respiratory disease (URD), and 16.2% had been diagnosed with pneumonia. There were no cases of influenza, pneumonia, or hospitalization in the 2019 season; 49.3% of the participants developed a URD (n = 74). Among participants who had been vaccinated during both influenza seasons, 47.5% had had and/or developed a URD, with a higher number of cases during the 2018-2019 season.

CONCLUSIONS:

After vaccination, no cases of influenza, hospitalization, and pneumonia were observed and the incidence of URD decreased compared with that of the previous season.

Improving immunogenicity of influenza virus H7N9 recombinant hemagglutinin for vaccine development

Human infections of novel avian influenza A virus (H7N9) emerged in early 2013 and caused about 40% case-fatality through 2017. Therefore, development of influenza H7N9 vaccines is critical for pandemic preparedness. Currently, there are three means of production of commercial influenza vaccines: egg-based, mammalian cell-based, and insect cell-based platforms. The insect cell-based platform has the advantage of high speed in producing recombinant protein. In this study, we evaluate the stability and immunogenicity of two different influenza H7 HA expression constructs generated using the baculovirus system, including membrane-based full-length HA (mH7) and secreted ectodomain-based H7 (sH7). The mH7 construct could form an oligomer-rosette structure and had a high hemagglutinin (HA) titer 8192. In contrast to mH7, the sH7 construct could not form an oligomer-rosette structure and did not have HA titer before cross-linking with anti-His antibody. Thermal stability tests showed that the sH7 and mH7 constructs were unstable at 43 °C and 52 °C, respectively. In a mice immunization study, the mH7 construct but not the sH7 construct could induce robust HI and neutralizing antibody titers. In conclusion, further development of the mH7 vaccine candidate is desirable.

Safety of Recombinant Influenza Vaccine Compared to Inactivated Influenza Vaccine in Adults: An Observational Study

Background

Recombinant trivalent influenza vaccine (RIV3) was initially licensed in 2013 and approved for all adults ≥18 in 2014. This study evaluated the safety of RIV3 compared with trivalent standard-dose, inactivated influenza vaccine (IIV3) in Kaiser Permanente Northern California (KPNC).

Methods

This Phase 4 observational, postmarketing safety study included persons ≥18 years vaccinated with RIV3 or IIV3 in KPNC during the 2015-2016 influenza season. We compared (1) the rates of prespecified diagnoses of interest (Guillain-Barré Syndrome, pericarditis, pleural effusion, narcolepsy/cataplexy, asthma, acute hypersensitivity reactions, and fever) during various postvaccination risk intervals as well as (2) all-cause hospitalization and mortality 0-180 days after vaccination. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using logistic regression analyses adjusted for age, sex, race/ethnicity, month of vaccination, and concomitant receipt of other vaccinations.

Results

Comparing the 21 976 persons who received RIV3 with the 283 683 who received IIV3, there were statistically significant differences in the prespecified diagnoses of interest between the 2 groups. Specifically, RIV3 vaccination was associated with fewer fever diagnoses during the 0-41 days postvaccination (OR, 0.38; 95% CI, 0.14-0.86). Also, RIV3 was associated with fewer all-cause hospitalizations during the 0-180 days postvaccination (OR, 0.66; 95% CI, 0.61-0.73), which was mostly related to pregnancy-related hospitalizations in IIV3 recipients. There were no serious adverse events or deaths related to RIV3.

Conclusions

This study did not identify any safety concerns regarding the use of RIV3 in adults.

Influenza Vaccination in Older Adults: Recent Innovations and Practical Applications

Influenza can lead to serious illness, particularly for older adults. In addition to short-term morbidity and mortality during the acute infection, recovery can be prolonged and often incomplete. This may lead to persistent declines in health and function, including catastrophic disability, which has dramatic implications for the well-being and support needs of older adults and their caregivers. All of this means that prevention of infection and effective treatment when illness has occurred are of paramount importance. In this narrative review, we discuss the effectiveness of influenza vaccines for the prevention of influenza illness and serious outcomes in older adults. We review evidence of vaccine effectiveness for older adults in comparison with younger age groups, and also highlight the importance of frailty as a determinant of vaccine effectiveness. We then turn our attention to the question of why older and frailer individuals have poorer vaccine responses, and consider changes in immune function and inflammatory responses. This sets the stage for a discussion of newer influenza vaccine products that have been developed with the aim of enhancing vaccine effectiveness in older adults. We review the available evidence on vaccine efficacy, effectiveness and cost benefits, consider the potential place of these innovations in clinical geriatric practice, and discuss international advisory committee recommendations on influenza vaccination in older adults. Finally, we highlight the importance of influenza prevention to support healthy aging, along with the need to improve vaccine coverage rates using available vaccine products, and to spur development of better influenza vaccines for older adults in the near future.

Influenza vaccines: Evaluation of the safety profile

The safety of vaccines is a critical factor in maintaining public trust in national vaccination programs. Vaccines are recommended for children, adults and elderly subjects and have to meet higher safety standards, since they are administered to healthy subjects, mainly healthy children. Although vaccines are strictly monitored before authorization, the possibility of adverse events and/or rare adverse events cannot be totally eliminated. Two main types of influenza vaccines are currently available: parenteral inactivated influenza vaccines and intranasal live attenuated vaccines. Both display a good safety profile in adults and children. However, they can cause adverse events and/or rare adverse events, some of which are more prevalent in children, while others with a higher prevalence in adults. The aim of this review is to provide an overview of influenza vaccine safety according to target groups, vaccine types and production methods.

Randomized Comparison of Immunogenicity and Safety of Quadrivalent Recombinant Versus Inactivated Influenza Vaccine in Healthy Adults 18-49 Years of Age

Background

Seasonal influenza vaccines are transitioning to quadrivalent formulations including the hemagglutinins of influenza A subtypes H1N1 and H3N2 and B lineages Yamagata and Victoria.

Methods

A new quadrivalent recombinant influenza vaccine (RIV4) was compared directly with a standard-dose, egg-grown, quadrivalent-inactivated influenza vaccine (IIV4) for immunogenicity and safety in adults 18-49 years of age. The coprimary endpoints for noninferiority were hemagglutination inhibition seroconversion rates and postvaccination geometric mean titer ratios for each antigen using US regulatory criteria. Reactogenicity solicited for 7 days, other safety events collected for 28 days, and serious or medically attended adverse events collected for 6 months after vaccination comprised the safety evaluation.

Results

The immunogenicity of RIV4 was comparable to that of IIV4; the coprimary noninferiority criteria were met for 3 antigens, and the antibody responses to the fourth antigen, influenza B/Brisbane/60/2008, were low in each group, making comparisons uninterpretable. Systemic and injection site reactions were mild, transient, and similar in each group, whereas none of the spontaneously reported adverse events, serious or nonserious, were considered related to study vaccine.

Conclusions

This first head-to-head comparison of recombinant versus inactivated quadrivalent influenza vaccines in 18-49 year old adults showed comparable immunogenicity, safety, and tolerability for both vaccines.

The Unexpected Impact of Vaccines on Secondary Bacterial Infections Following Influenza

Influenza virus infections remain a significant health burden worldwide, despite available vaccines. Factors that contribute to this include a lack of broad coverage by current vaccines and continual emergence of novel virus strains. Further complicating matters, when influenza viruses infect a host, severe infections can develop when bacterial pathogens invade. Secondary bacterial infections (SBIs) contribute to a significant proportion of influenza-related mortality, with Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, and Haemophilus influenzae as major coinfecting pathogens. Vaccines against bacterial pathogens can reduce coinfection incidence and severity, but few vaccines are available and those that are, may have decreased efficacy in influenza virus-infected hosts. While some studies indicate a benefit of vaccine-induced immunity in providing protection against SBIs, a comprehensive understanding is lacking. In this review, we discuss the current knowledge of viral and bacterial vaccine availability, the generation of protective immunity from these vaccines, and the effectiveness in limiting influenza-associated bacterial infections.

Vaccine approaches conferring cross-protection against influenza viruses

INTRODUCTION

Annual vaccination is one of the most efficient and cost-effective strategies to prevent and control influenza epidemics. Most of the currently available influenza vaccines are strong inducers of antibody responses against viral surface proteins, hemagglutinin (HA) and neuraminidase (NA), but are poor inducers of cell-mediated immune responses against conserved internal proteins. Moreover, due to the high variability of viral surface proteins because of antigenic drift or antigenic shift, many of the currently licensed vaccines confer little or no protection against drift or shift variants. Areas covered: Next generation influenza vaccines that can induce humoral immune responses to receptor-binding epitopes as well as broadly neutralizing conserved epitopes, and cell-mediated immune responses against highly conserved internal proteins would be effective against variant viruses as well as a novel pandemic influenza until circulating strain-specific vaccines become available. Here we discuss vaccine approaches that have the potential to provide broad spectrum protection against influenza viruses. Expert commentary: Based on current progress in defining cross-protective influenza immunity, it seems that the development of a universal influenza vaccine is feasible. It would revolutionize the strategy for influenza pandemic preparedness, and significantly impact the shelf-life and protection efficacy of seasonal influenza vaccines.

Prevention and Control of Seasonal Influenza with Vaccines

This report updates the 2015-16 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines (Grohskopf LA, Sokolow LZ, Olsen SJ, Bresee JS, Broder KR, Karron RA. Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices, United States, 2015-16 influenza season. MMWR Morb Mortal Wkly Rep 2015;64:818-25). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For the 2016-17 influenza season, inactivated influenza vaccines (IIVs) will be available in both trivalent (IIV3) and quadrivalent (IIV4) formulations. Recombinant influenza vaccine (RIV) will be available in a trivalent formulation (RIV3). In light of concerns regarding low effectiveness against influenza A(H1N1)pdm09 in the United States during the 2013-14 and 2015-16 seasons, for the 2016-17 season, ACIP makes the interim recommendation that live attenuated influenza vaccine (LAIV4) should not be used. Vaccine virus strains included in the 2016-17 U.S. trivalent influenza vaccines will be an A/California/7/2009 (H1N1)-like virus, an A/Hong Kong/4801/2014 (H3N2)-like virus, and a B/Brisbane/60/2008-like virus (Victoria lineage). Quadrivalent vaccines will include an additional influenza B virus strain, a B/Phuket/3073/2013-like virus (Yamagata lineage).Recommendations for use of different vaccine types and specific populations are discussed. A licensed, age-appropriate vaccine should be used. No preferential recommendation is made for one influenza vaccine product over another for persons for whom more than one licensed, recommended product is otherwise appropriate. This information is intended for vaccination providers, immunization program personnel, and public health personnel. Information in this report reflects discussions during public meetings of ACIP held on October 21, 2015; February 24, 2016; and June 22, 2016. These recommendations apply to all licensed influenza vaccines used within Food and Drug Administration-licensed indications, including those licensed after the publication date of this report. Updates and other information are available at CDC's influenza website (http://www.cdc.gov/flu). Vaccination and health care providers should check CDC's influenza website periodically for additional information.