influenza vaccines

Background
Influenza vaccines are available to help protect persons aged ≥65 years, who experience thousands of influenza hospitalizations annually. Because some influenza vaccines may work better than others, we sought to assess benefit of high-dose (HD), adjuvanted (ADJ), and recombinant (RIV) influenza vaccines (“enhanced influenza vaccines”) compared with standard-dose unadjuvanted influenza vaccines (SD) and with one another for prevention of influenza-associated hospitalizations among persons aged ≥65 years.

Methods
We searched MEDLINE, Embase, CINAHL, Scopus, and Cochrane Library to identify randomized or observational studies published between January 1990 and October 2023 and reporting relative vaccine effectiveness (rVE) of HD, ADJ, or RIV for prevention of influenza-associated hospitalizations among adults aged ≥65 years. We extracted study data, assessed risk of bias, and conducted random-effects network meta-analysis and meta-regression.

Results
We identified 32 studies with 90 rVE estimates from five randomized and 27 observational studies (71,459,918 vaccinated participants). rVE estimates varied across studies and influenza seasons. Pooled rVE from randomized studies was 20% (95% CI −54 to 59) and 25% (95% CI −19 to 53) for ADJ and HD compared with SD, respectively; rVE was 6% (95% CI −109 to 58) for HD compared with ADJ; these differences were not statistically significant. In observational studies, ADJ, HD, and RIV conferred modestly increased protection compared with SD (rVE ranging from 10% to 19%), with no significant differences between HD, ADJ, and RIV. With enhanced vaccines combined, rVE versus SD was 18% (95% CI 3 to 32) from randomized and 11% (95% CI 8 to 14) from observational evidence. Meta-regression of observational studies suggested that those requiring laboratory confirmation of influenza reported greater benefit of enhanced vaccines.

Conclusions
HD, ADJ, and RIV provided stronger protection than SD against influenza hospitalizations among older adults. No differences in benefit were observed in comparisons of enhanced influenza vaccines with one another.

Author/s:

J M Ferdinands, L H Blanton, E Alyanak, J R Chung, L Trujillo

Association of Influenza Vaccination With Cardiovascular Risk: A Meta-analysis

Saige Blanchard — Tue, 10 May 2022 05:00:00 +0000

Date Added:

May 10, 2022

Journal/Publication:

JAMA Network Open

Publisher:

JAMA Network Open

Publication Date:

April 29, 2022

Issue:

Volume:

Pages:

1-9

URL:

Association of Influenza Vaccination With Cardiovascular Risk: A Meta-analysis

Type:

Meta-analyses, Reviews, and Guidelines

Format:

Article

DOI (1):

10.1001/jamanetworkopen.2022.8873

Keywords

PMID (1):

35486404

MeSH

influenza vaccines

acute coronary syndrome

Odds Ratio

COVID-19

follow-up studies

It appears that the influenza vaccine somehow reduces the risk of cardiovascular events over the subsequent year by almost 2%, which is about as effective as lowering blood pressure in older people. At the very least, it could be another way to convince people to get immunized. James W. Mold, MD, MPH

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Importance: Influenza infection is associated with increased cardiovascular hospitalization and mortality. Our prior systematic review and meta-analysis hypothesized that influenza vaccination was associated with a lower risk of cardiovascular events.

Objective: To evaluate, via an updated meta-analysis, if seasonal influenza vaccination is associated with a lower risk of fatal and nonfatal cardiovascular events and assess whether the newest cardiovascular outcome trial results are consistent with prior findings.

Data sources: A previously published meta-analysis of randomized controlled trials (RCTs) and a large 2021 cardiovascular outcome trial.

Study selection: Studies with RCTs published between 2000 and 2021 that randomized participants to either influenza vaccine or placebo/control. Eligible participants were inpatients and outpatients recruited for international multicenter RCTs and randomized to receive either influenza vaccine or placebo/control.

Data extraction and synthesis: PRISMA guidelines were followed in the extraction of study details, and risk of bias was assessed using the Cochrane Collaboration tool. Trial quality was evaluated using Cochrane criteria. Data were analyzed January 2020 and December 2021.

Main outcomes and measures: Random-effects Mantel-Haenszel risk ratios (RRs) and 95% CIs were derived for a composite of major adverse cardiovascular events and cardiovascular mortality within 12 months of follow-up. Where available, analyses were stratified by patients with and without recent acute coronary syndrome (ACS) within 1 year of randomization.

Results: Six published RCTs comprising a total of 9001 patients were included (mean age, 65.5 years; 42.5% women; 52.3% with a cardiac history). Overall, influenza vaccine was associated with a lower risk of composite cardiovascular events (3.6% vs 5.4%; RR, 0.66; 95% CI, 0.53-0.83; P < .001). A treatment interaction was detected between patients with recent ACS (RR, 0.55; 95% CI, 0.41-0.75) and without recent ACS (RR, 1.00; 95% CI, 0.68-1.47) (P for interaction = .02). For cardiovascular mortality, a treatment interaction was also detected between patients with recent ACS (RR, 0.44; 95% CI, 0.23-0.85) and without recent ACS (RR, 1.45; 95% CI, 0.84-2.50) (P for interaction = .006), while 1.7% of vaccine recipients died of cardiovascular causes compared with 2.5% of placebo or control recipients (RR, 0.74; 95% CI, 0.42-1.30; P = .29).

Conclusions and relevance: In this study, receipt of influenza vaccination was associated with a 34% lower risk of major adverse cardiovascular events, and individuals with recent ACS had a 45% lower risk. Given influenza poses a threat to population health during the COVID-19 pandemic, it is integral to counsel high-risk patients on the cardiovascular benefits of influenza vaccination.

Author/s:

Behrouzi, B., Bhatt, D. L., Cannon, C. P., Vardeny, O., Lee, D. S., Solomon, S. D., Udell, J. A.

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices, United States, 2021-22 Influenza Season

Bethie Seay — Thu, 26 Aug 2021 05:00:00 +0000

Date Added:

August 26, 2021

Type:

Public Health Announcements

MeSH

Influenza A Virus, H1N1 Subtype

SARS-CoV-2

influenza, human

vaccines, inactivated

Pregnancy Trimester, Third

Inpatients

prevalence

united states food and drug administration

Centers for Disease Control and Prevention, U.S.

Intensive Care Units

Cell Culture Techniques

delivery of health care

The 2021-2022 CDC recommendations regarding administration of influenza vaccines.

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This report updates the 2020–21 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2020;69[No. RR-8]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For each recipient, a licensed and age-appropriate vaccine should be used. ACIP makes no preferential recommendation for a specific vaccine when more than one licensed, recommended, and age-appropriate vaccine is available. During the 2021–22 influenza season, the following types of vaccines are expected to be available: inactivated influenza vaccines (IIV4s), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4).

The 2021–22 influenza season is expected to coincide with continued circulation of SARS-CoV-2, the virus that causes COVID-19. Influenza vaccination of persons aged ≥6 months to reduce prevalence of illness caused by influenza will reduce symptoms that might be confused with those of COVID-19. Prevention of and reduction in the severity of influenza illness and reduction of outpatient visits, hospitalizations, and intensive care unit admissions through influenza vaccination also could alleviate stress on the U.S. health care system. Guidance for vaccine planning during the pandemic is available at https://www.cdc.gov/vaccines/pandemic-guidance/index.html. Recommendations for the use of COVID-19 vaccines are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/covid-19.html, and additional clinical guidance is available at https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-v....

Updates described in this report reflect discussions during public meetings of ACIP that were held on October 28, 2020; February 25, 2021; and June 24, 2021. Primary updates to this report include the following six items. First, all seasonal influenza vaccines available in the United States for the 2021–22 season are expected to be quadrivalent. Second, the composition of 2021–22 U.S. influenza vaccines includes updates to the influenza A(H1N1)pdm09 and influenza A(H3N2) components. U.S.-licensed influenza vaccines will contain hemagglutinin derived from an influenza A/Victoria/2570/2019 (H1N1)pdm09-like virus (for egg-based vaccines) or an influenza A/Wisconsin/588/2019 (H1N1)pdm09-like virus (for cell culture–based and recombinant vaccines), an influenza A/Cambodia/e0826360/2020 (H3N2)-like virus, an influenza B/Washington/02/2019 (Victoria lineage)-like virus, and an influenza B/Phuket/3073/2013 (Yamagata lineage)-like virus. Third, the approved age indication for the cell culture–based inactivated influenza vaccine, Flucelvax Quadrivalent (ccIIV4), has been expanded from ages ≥4 years to ages ≥2 years. Fourth, discussion of administration of influenza vaccines with other vaccines includes considerations for coadministration of influenza vaccines and COVID-19 vaccines. Providers should also consult current ACIP COVID-19 vaccine recommendations and CDC guidance concerning coadministration of these vaccines with influenza vaccines. Vaccines that are given at the same time should be administered in separate anatomic sites. Fifth, guidance concerning timing of influenza vaccination now states that vaccination soon after vaccine becomes available can be considered for pregnant women in the third trimester. As previously recommended, children who need 2 doses (children aged 6 months through 8 years who have never received influenza vaccine or who have not previously received a lifetime total of ≥2 doses) should receive their first dose as soon as possible after vaccine becomes available to allow the second dose (which must be administered ≥4 weeks later) to be received by the end of October. For nonpregnant adults, vaccination in July and August should be avoided unless there is concern that later vaccination might not be possible. Sixth, contraindications and precautions to the use of ccIIV4 and RIV4 have been modified, specifically with regard to persons with a history of severe allergic reaction (e.g., anaphylaxis) to an influenza vaccine. A history of a severe allergic reaction to a previous dose of any egg-based IIV, LAIV, or RIV of any valency is a precaution to use of ccIIV4. A history of a severe allergic reaction to a previous dose of any egg-based IIV, ccIIV, or LAIV of any valency is a precaution to use of RIV4. Use of ccIIV4 and RIV4 in such instances should occur in an inpatient or outpatient medical setting under supervision of a provider who can recognize and manage a severe allergic reaction; providers can also consider consulting with an allergist to help identify the vaccine component responsible for the reaction. For ccIIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any ccIIV of any valency or any component of ccIIV4 is a contraindication to future use of ccIIV4. For RIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any RIV of any valency or any component of RIV4 is a contraindication to future use of RIV4.

This report focuses on recommendations for the use of vaccines for the prevention and control of seasonal influenza during the 2021–22 influenza season in the United States. A brief summary of the recommendations and a link to the most recent Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used according to Food and Drug Administration–licensed indications. Updates and other information are available from CDC’s influenza website (https://www.cdc.gov/flu); vaccination and health care providers should check this site periodically for additional information.

Author/s:

Grohskopf, L. A., Alyanak, E., Ferdinands, J. M., Broder, K. R., Blanton, L. H., Talbot, H. K., Fry, A. M.

Influenza Vaccine for 2020-2021

Carly Hughes — Tue, 06 Oct 2020 13:56:34 +0000

Date Added:

October 6, 2020

Publisher:

JAMA

Publication Date:

October 2, 2020

Pages:

E1-E2

URL:

Influenza Vaccine for 2020-2021

Type:

Public Health Announcements

Format:

Article

DOI (1):

doi:10.1001/jama.2020.19507

Keywords

influenza vaccine

MeSH

influenza vaccines

A summary of the characteristics of and indications for the various influenza vaccines available for the 2020-2021 season from The Medical Letter. James W. Mold,. MD

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Not available.

Author/s:

American Medical Association

Routine Childhood Vaccines Given From 1 through 18 Years of Age

Brian Desmarais — Mon, 10 Aug 2020 18:25:18 +0000

Date Added:

August 10, 2020

Journal/Publication:

Mayo Clinic Proceedings

Publication Date:

August 1, 2020

Issue:

Volume:

Pages:

1780-1795

URL:

Routine Childhood Vaccines Given From 1 through 18 Years of Age

Type:

Meta-analyses, Reviews, and Guidelines

Format:

Article

DOI (1):

10.1016/j.mayocp.2020.06.004

MeSH

influenza, human

Vaccine-Preventable Diseases

Meningococcal Vaccines

Haemophilus influenzae type b

measles-mumps-rubella vaccine

Diphtheria-Tetanus-acellular Pertussis Vaccines

child

An excellent review of the recommendations, rationales, and results of childhood immunizations. James W. Mold, MD, MPH

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In addition to the vaccines due in the first year of life, the US Advisory Committee on Immunization Practices recommends that children continue to receive vaccines regularly against a variety of infectious diseases. Starting at 12 to 15 months of life, these include the two-dose measles-mumps-rubella vaccine series and the two-dose varicella vaccine series. Also in the second year of life, infants should begin the two-dose hepatitis A vaccine series and complete the Haemophilus influenzae type B vaccine series as well as the pneumococcal conjugate vaccine series. Before 19 months of life, infants should receive the third dose of the poliovirus vaccine and the fourth dose of diphtheria-tetanus-acellular pertussis (DTaP) vaccine. The final doses of poliovirus and tetanus-diphtheria-acellular pertussis vaccines are both due at 4 to 6 years of life. Before each influenza season, every child should receive the influenza vaccine. Those less than 9 years of age who previously received less than two doses need two doses a month apart. At 11 to 12 years of life, all should get two doses of the human papillomavirus vaccine, the adolescent/adult version of the tetanus-diphtheria-acellular pertussis vaccine, and begin a two-dose series of meningococcal ACWY vaccine. Each of these vaccines is due when the vaccine works to protect against both an immediate risk as well as to provide long-term protection. Each vaccine-preventable disease varies in terms of the nature of exposure, the form of the morbidity, the risk of mortality, and potential to prevent or ameliorate its harm.

Author/s:

Jacobson, RM

Vaccination of Adults in General Medical Practice

Brian Desmarais — Fri, 03 Jan 2020 19:37:26 +0000

Date Added:

January 3, 2020

Journal/Publication:

Mayo Clinic Proceedings

Publication Date:

January 1, 2020

Issue:

Volume:

Pages:

169–183

URL:

Vaccination of Adults in General Medical Practice

Type:

Meta-analyses, Reviews, and Guidelines

Format:

Article

DOI (1):

https://doi.org/10.1016/j.mayocp.2019.02.024

Keywords

adult immunization

A review of adult immunization recommendations from Mayo. James W. Mold, MD, MPH

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In vaccinating adults, clinicians face 2 types of challenges: (1) staying current on recommendations for influenza, pneumococcal, hepatitis A and B, zoster, and other vaccines and (2) addressing systemic barriers to implementing practices that increase vaccination rates. Although adult immunization rates remain suboptimal, there has been much good news in adult vaccination recently. New high-dose and adjuvanted influenza vaccines help improve immune response and may reduce influenza complications in older adults. The new recombinant zoster vaccine offers significantly more efficacy against zoster outbreaks and postherpetic neuralgia than zoster vaccine live. Pertussis vaccine given during the third trimester of pregnancy may prevent between 50% and 90% of pertussis infections in infants. Shorter time for completion (1 vs 6 months) of new, adjuvanted hepatitis B vaccine may increase adherence. Clinicians can address systemic barriers to increasing vaccination rates in their clinics and health care systems by following the Centers for Disease Control and Prevention's Standards for Adult Immunization Practice. Clinicians can help increase vaccination rates by writing standing orders and by advocating for nurses or medical assistants to receive training and protected time for assessing and documenting vaccination histories and administration. Strong recommendations that presume acceptance of vaccination are effective with most patients. Communication techniques similar to motivational interviewing can help with vaccine-hesitant patients. Clinicians, as experts on providing preventive services, can educate community leaders about the benefits of immunization and can inform vaccine experts about challenges of implementing vaccination recommendations in clinical practice and strategies that can work to raise vaccination rates.

Author/s:

Hunter, P., Fryhofer, S.A., Szilagyi, P.

Routine Childhood Vaccines Given in the First 11 Months After Birth

John Bayhi — Thu, 02 Jan 2020 20:22:28 +0000

Date Added:

January 2, 2020

Journal/Publication:

Mayo Clinic Proceedings

Publisher:

Elsevier Inc.

Publication Date:

December 23, 2019

URL:

Routine Childhood Vaccines Given in the First 11 Months After Birth

Type:

Meta-analyses, Reviews, and Guidelines

Format:

Article

DOI (1):

10.1016/j.mayocp.2019.06.007

Keywords

vaccines

infants

immunizations

PMID (1):

31879133

MeSH

Haemophilus influenzae type b

Influenza

Human

Rotavirus

Strepococcus pneumoniae

Poliovirus

Advisory Committees

Vaccine-Preventable Diseases

This is a nice review from Mayo of the vaccines recommended for children under the age of one including rationale, effectiveness, and concerns.

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The US Advisory Committee on Immunization Practices recommends that infants beginning at birth receive several vaccines directed against a variety of infectious diseases that currently pose threats of morbidity and mortality to infants and those around them, including the 3-dose hepatitis B (HepB) series. The first dose is due at birth. This series protects against maternal-infant transmission of the HepB virus and against exposure the rest of the infant's life. At age 2 months infants are to receive not only their second dose of HepB vaccine but also a series of vaccines directed against diphtheria, tetanus, pertussis, pneumococcus, rotavirus, poliovirus, and Haemophilus influenzae type b. At 4 months, infants are to repeat those vaccines except for the HepB vaccine. At age 6 months infants are to finish the HepB series and receive the third doses of the other vaccines received at 2 and 4 months except for the rotavirus vaccine, depending on the brand used. Also, starting at 6 months, depending on the time of year, infants are to begin a 2-dose series against influenza separated by 28 days. Each of these vaccines is due at a time when the vaccine works to protect against an immediate risk and to provide long-term protection. These vaccine-preventable diseases vary in terms of the nature of exposure, the form of the morbidity, the risk of mortality, and the ability of routine vaccination to prevent or ameliorate harm.

Author/s:

Jacobson, RM

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices - United States, 2019-20 Influenza Season

Brian Desmarais — Mon, 30 Sep 2019 13:16:17 +0000

Date Added:

September 30, 2019

Journal/Publication:

Morbidity and Mortality Weekly Report

Publication Date:

August 23, 2019

Issue:

Volume:

Pages:

1-21

URL:

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices - United States, 2019-20 Influenza Seaso

Type:

Public Health Announcements

Format:

Article

DOI (1):

10.15585/mmwr.rr6803a1

Keywords

Flu vaccines

vaccination recommendations

Centers for Disease Control and Prevention

MeSH

vaccines, inactivated

Hemagglutinins

Influenza A Virus, H1N1 Subtype

Influenza A Virus, H3N2 Subtype

united states food and drug administration

centers for disease control and prevention (U.S.)

Contraindications

This year’s flu vaccine recommendations from the CDC. James W. Mold, MD, MPH

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Abstract

This report updates the 2018-19 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2018;67[No. RR-3]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. A licensed, recommended, and age-appropriate vaccine should be used. Inactivated influenza vaccines (IIVs), recombinant influenza vaccine (RIV), and live attenuated influenza vaccine (LAIV) are expected to be available for the 2019-20 season. Standard-dose, unadjuvanted, inactivated influenza vaccines will be available in quadrivalent formulations (IIV4s). High-dose (HD-IIV3) and adjuvanted (aIIV3) inactivated influenza vaccines will be available in trivalent formulations. Recombinant (RIV4) and live attenuated influenza vaccine (LAIV4) will be available in quadrivalent formulations.Updates to the recommendations described in this report reflect discussions during public meetings of ACIP held on October 25, 2018; February 27, 2019; and June 27, 2019. Primary updates in this report include the following two items. First, 2019-20 U.S. trivalent influenza vaccines will contain hemagglutinin (HA) derived from an A/Brisbane/02/2018 (H1N1)pdm09-like virus, an A/Kansas/14/2017 (H3N2)-like virus, and a B/Colorado/06/2017-like virus (Victoria lineage). Quadrivalent influenza vaccines will contain HA derived from these three viruses, and a B/Phuket/3073/2013-like virus (Yamagata lineage). Second, recent labeling changes for two IIV4s, Afluria Quadrivalent and Fluzone Quadrivalent, are discussed. The age indication for Afluria Quadrivalent has been expanded from ≥5 years to ≥6 months. The dose volume for Afluria Quadrivalent is 0.25 mL for children aged 6 through 35 months and 0.5 mL for all persons aged ≥36 months (≥3 years). The dose volume for Fluzone Quadrivalent for children aged 6 through 35 months, which was previously 0.25 mL, is now either 0.25 mL or 0.5 mL. The dose volume for Fluzone Quadrivalent is 0.5 mL for all persons aged ≥36 months (≥3 years).This report focuses on the recommendations for use of vaccines for the prevention and control of influenza during the 2019-20 season in the United States. A brief summary of these recommendations and a Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used within Food and Drug Administration-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check this site periodically for additional information.

Author/s:

Grohskopf, L.A., Alyanak, E., Broder, K.R., Walter, E.B., Fry, A.M., Jernigan, D.B.

Vaccines for preventing influenza in healthy adults

Tracy Ashby — Wed, 30 Jan 2019 06:00:00 +0000

Date Added:

January 30, 2019

Journal/Publication:

Cochrane Database of Systematic Reviews 2018

Publisher:

John Wiley and Sons

Publication Date:

February 1, 2018

Issue:

URL:

Vaccines for preventing influenza in healthy adults.

Type:

Meta-analyses, Reviews, and Guidelines

Format:

Article

DOI (1):

10.1002/14651858.CD001269.pub6

Keywords

vaccination

PMID (1):

29388196

MeSH

influenza, human

influenza vaccines

pandemics

vaccines, inactivated

pregnancy

In a typical year, in healthy adults, influenza vaccination reduces the probability of developing a flu-like illness from 21.5% to 18.1%. History of vaccination should not be used when deciding whether an adult patient has the flu.

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BACKGROUND:

The consequences of influenza in adults are mainly time off work. Vaccination of pregnant women is recommended internationally. This is an update of a review published in 2014. Future updates of this review will be made only when new trials or vaccines become available. Observational data included in previous versions of the review have been retained for historical reasons but have not been updated due to their lack of influence on the review conclusions.

OBJECTIVES:

To assess the effects (efficacy, effectiveness, and harm) of vaccines against influenza in healthy adults, including pregnant women.

SEARCH METHODS:

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 12), MEDLINE (January 1966 to 31 December 2016), Embase (1990 to 31 December 2016), the WHO International Clinical Trials Registry Platform (ICTRP; 1 July 2017), and ClinicalTrials.gov (1 July 2017), as well as checking the bibliographies of retrieved articles.

SELECTION CRITERIA:

Randomised controlled trials (RCTs) or quasi-RCTs comparing influenza vaccines with placebo or no intervention in naturally occurring influenza in healthyindividuals aged 16 to 65 years. Previous versions of this review included observational comparative studies assessing serious and rare harms cohort and case-control studies. Due to the uncertain quality of observational (i.e. non-randomised) studies and their lack of influence on the review conclusions, we decided to update only randomised evidence. The searches for observational comparative studies are no longer updated.

DATA COLLECTION AND ANALYSIS:

Two review authors independently assessed trial quality and extracted data. We rated certainty of evidence for key outcomes (influenza, influenza-like illness (ILI), hospitalisation, and adverse effects) using GRADE.

MAIN RESULTS:

We included 52 clinical trials of over 80,000 people assessing the safety and effectiveness of influenza vaccines. We have presented findings from 25 studies comparing inactivated parenteral influenza vaccine against placebo or do-nothing control groups as the most relevant to decision-making. The studies were conducted over single influenza seasons in North America, South America, and Europe between 1969 and 2009. We did not consider studies at high risk of bias to influence the results of our outcomes except for hospitalisation.Inactivated influenza vaccines probably reduce influenza in healthy adults from 2.3% without vaccination to 0.9% (risk ratio (RR) 0.41, 95% confidence interval (CI) 0.36 to 0.47; 71,221 participants; moderate-certainty evidence), and they probably reduce ILI from 21.5% to 18.1% (RR 0.84, 95% CI 0.75 to 0.95; 25,795 participants; moderate-certainty evidence; 71 healthy adults need to be vaccinated to prevent one of them experiencing influenza, and 29 healthy adults need to be vaccinated to prevent one of them experiencing an ILI). The difference between the two number needed to vaccinate (NNV) values depends on the different incidence of ILI and confirmed influenza among the study populations. Vaccination may lead to a small reduction in the risk of hospitalisation in healthy adults, from 14.7% to 14.1%, but the CI is wide and does not rule out a large benefit (RR 0.96, 95% CI 0.85 to 1.08; 11,924 participants; low-certainty evidence). Vaccines may lead to little or no small reduction in days off work (-0.04 days, 95% CI -0.14 days to 0.06; low-certainty evidence). Inactivated vaccines cause an increase in fever from 1.5% to 2.3%.We identified one RCT and one controlled clinical trial assessing the effects of vaccination in pregnant women. The efficacy of inactivated vaccine containing pH1N1 against influenza was 50% (95% CI 14% to 71%) in mothers (NNV 55), and 49% (95% CI 12% to 70%) in infants up to 24 weeks (NNV 56). No data were available on efficacy against seasonal influenza during pregnancy. Evidence from observational studies showed effectiveness of influenza vaccines against ILI in pregnant women to be 24% (95% CI 11% to 36%, NNV 94), and against influenza in newborns from vaccinated women to be 41% (95% CI 6% to 63%, NNV 27).Live aerosol vaccines have an overall effectiveness corresponding to an NNV of 46. The performance of one- or two-dose whole-virion 1968 to 1969 pandemic vaccines was higher (NNV 16) against ILI and (NNV 35) against influenza. There was limited impact on hospitalisations in the 1968 to 1969 pandemic (NNV 94). The administration of both seasonal and 2009 pandemic vaccines during pregnancy had no significant effect on abortion or neonatal death, but this was based on observational data sets.

AUTHORS' CONCLUSIONS:

Healthy adults who receive inactivated parenteral influenzavaccine rather than no vaccine probably experience less influenza, from just over 2% to just under 1% (moderate-certainty evidence). They also probably experience less ILI following vaccination, but the degree of benefit when expressed in absolute terms varied across different settings. Variation in protection against ILI may be due in part to inconsistent symptom classification. Certainty of evidence for the small reductions in hospitalisations and time off work is low. Protection against influenza and ILI in mothers and newborns was smaller than the effects seen in other populations considered in this review.Vaccines increase the risk of a number of adverse events, including a small increase in fever, but rates of nausea and vomiting are uncertain. The protective effect of vaccination in pregnant women and newborns is also very modest. We did not find any evidence of an association between influenzavaccination and serious adverse events in the comparative studies considered in this review. Fifteen included RCTs were industry funded (29%).

Update of

Vaccines for preventing influenza in healthy adults. [Cochrane Database Syst Rev. 2014]

Author/s:

Demicheli, Vittorio, Jefferson, Tom, Ferroni, Eliana, Rivetti, Alessandro, Pietrantonj, Carlo Di

Interpretation of Rapid Influenza Diagnostic Test (RIDT) Results

Jeffrey Wilson — Mon, 07 Jan 2019 16:15:20 +0000

Date Added:

January 7, 2019

Publication Date:

January 7, 2019

URL:

Interpretation of Rapid Influenza Diagnostic Test (RIDT) Results

Type:

Clinical Decision Aids

Format:

Article

Keywords

flu

influenza

RIDT

rapid influenza diagnostic test

MeSH

influenza, human

influenza vaccines

diagnostic tests, routine

antigens, viral

This information on interpretation of rapid antigen tests for influenza was condensed from information on the CDC website.

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A number of factors can influence the results of RIDTs. The accuracy of RIDTs depends largely on the conditions under which they are used.

Author/s:

Mold, James, Centers for Disease Control and Prevention (CDC)

Interpretation of Rapid Influenza Diagnostic Test (RIDT) Results

Tracy Ashby — Sun, 06 Jan 2019 06:00:00 +0000

Date Added:

January 6, 2019

Type:

Clinical Decision Aids

Format:

Article

Keywords

rapid influenza diagnostic test

MeSH

orthomyxoviridae infections

antigens

viral

This information on interpretation of rapid antigen tests for influenza was condensed from information on the CDC website.

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A number of factors can influence the results of RIDTs. The accuracy of Rapid Influenza Diagnostic Tests (RIDTs) depends largely on the conditions under which they are used.

Prevention and Control of Seasonal Influenza with Vaccines

Jeffrey Wilson — Wed, 03 Oct 2018 17:31:30 +0000

Date Added:

October 3, 2018

Publisher:

Centers for Disease Control and Prevention

Publication Date:

August 23, 2018

URL:

2018-19 Summary of Recommendations

Type:

Public Health Announcements

Format:

Web Page

Keywords

MeSH

CDC/ACIP recommendations regarding influenza vaccination for the 2018-2019 season.

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Groups Recommended for Vaccination

Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications.
A licensed, age-appropriate influenza vaccine (IIV, RIV4, or LAIV4) should be used. Consult package information for age indications.
Emphasis should be placed on vaccination of high-risk groups and their contacts/caregivers. When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to (no hierarchy implied by order listed):
- Children aged 6–59 months;
- Adults aged ≥50 years;
- Persons with chronic pulmonary (including asthma), cardiovascular (excluding isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus);
- Persons who are immunocompromised due to any cause, (including medications or HIV infection);
- Women who are or will be pregnant during the influenza season;
- Children and adolescents (aged 6 months through 18 years) receiving aspirin- or salicylate-containing medications and who might be at risk for Reye syndrome;
- Residents of nursing homes and other long-term care facilities;
- American Indians/Alaska Natives;
- Persons who are extremely obese (BMI ≥40); and
- Caregivers and contacts of those at risk:
  - Health care personnel in inpatient and outpatient care settings, medical emergency-response workers, employees of nursing home and long-term care facilities who have contact with patients or residents, and students in these professions who will have contact with patients;
  - Household contacts and caregivers of children aged ≤59 months (i.e., <5 years), particularly contacts of children aged <6 months, and adults aged ≥50 years; and
  - Household contacts and caregivers of persons with medical conditions that put them at high risk of severe complications from influenza.

Author/s:

Advisory Committee on Immunization Practices