influenza

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.

N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial

John Bayhi — Mon, 23 Mar 2020 22:10:43 +0000

Date Added:

March 23, 2020

Journal/Publication:

JAMA

Publisher:

American Medical Association

Publication Date:

September 3, 2019

Issue:

Volume:

222

Pages:

824-833

URL:

N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial

Format:

Article

DOI (1):

10.1001/jama.2019.11645

Keywords

respiratory disease

respiratory infections

PMID (1):

31479137

This large RCT appears to confirm prior studies showing that regular surgical masks work just as well (or poorly) as N95 masks from preventing influenza in front line health care workers. James W. Mold, MD, MPH

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IMPORTANCE:

Clinical studies have been inconclusive about the effectiveness of N95 respirators and medical masks in preventing health care personnel (HCP) from acquiring workplace viral respiratory infections.

OBJECTIVE:

To compare the effect of N95 respirators vs medical masks for prevention of influenza and other viral respiratory infections among HCP.

DESIGN, SETTING, AND PARTICIPANTS:

A cluster randomized pragmatic effectiveness study conducted at 137 outpatient study sites at 7 US medical centers between September 2011 and May 2015, with final follow-up in June 2016. Each year for 4 years, during the 12-week period of peak viral respiratory illness, pairs of outpatient sites (clusters) within each center were matched and randomly assigned to the N95 respirator or medical mask groups.

INTERVENTIONS:

Overall, 1993 participants in 189 clusters were randomly assigned to wear N95 respirators (2512 HCP-seasons of observation) and 2058 in 191 clusters were randomly assigned to wear medical masks (2668 HCP-seasons) when near patients with respiratory illness.

MAIN OUTCOMES AND MEASURES:

The primary outcome was the incidence of laboratory-confirmed influenza. Secondary outcomes included incidence of acute respiratory illness, laboratory-detected respiratory infections, laboratory-confirmed respiratory illness, and influenzalike illness. Adherence to interventions was assessed.

RESULTS:

Among 2862 randomized participants (mean [SD] age, 43 [11.5] years; 2369 [82.8%]) women), 2371 completed the study and accounted for 5180 HCP-seasons. There were 207 laboratory-confirmed influenza infection events (8.2% of HCP-seasons) in the N95 respirator group and 193 (7.2% of HCP-seasons) in the medical mask group (difference, 1.0%, [95% CI, -0.5% to 2.5%]; P = .18) (adjusted odds ratio [OR], 1.18 [95% CI, 0.95-1.45]). There were 1556 acute respiratory illness events in the respirator group vs 1711 in the mask group (difference, -21.9 per 1000 HCP-seasons [95% CI, -48.2 to 4.4]; P = .10); 679 laboratory-detected respiratory infections in the respirator group vs 745 in the mask group (difference, -8.9 per 1000 HCP-seasons, [95% CI, -33.3 to 15.4]; P = .47); 371 laboratory-confirmed respiratory illness events in the respirator group vs 417 in the mask group (difference, -8.6 per 1000 HCP-seasons [95% CI, -28.2 to 10.9]; P = .39); and 128 influenzalike illness events in the respirator group vs 166 in the mask group (difference, -11.3 per 1000 HCP-seasons [95% CI, -23.8 to 1.3]; P = .08). In the respirator group, 89.4% of participants reported "always" or "sometimes" wearing their assigned devices vs 90.2% in the mask group.

CONCLUSIONS AND RELEVANCE:

Among outpatient health care personnel, N95 respirators vs medical masks as worn by participants in this trial resulted in no significant difference in the incidence of laboratory-confirmed influenza.

TRIAL REGISTRATION:

ClinicalTrials.gov Identifier: NCT01249625.

Author/s:

Radonovich, LJ Jr, Simberkoff, MS, Bessesen, MT, Brown, AC, Cummings, DAT, Gaydos, CA, Los, JG, Krosche, AE, Gibert, CL, Gorse, GJ, Nyquist, AC, Reich, N.G., Rodriguez-Barradas, MC, Price, CS, Perl, TM, ResPECT investigators

Coronavirus Disease 2019 and Influenza

John Bayhi — Fri, 28 Feb 2020 14:05:34 +0000

Date Added:

February 28, 2020

Journal/Publication:

JAMA

Publisher:

American Medical Association

Publication Date:

February 26, 2020

Type:

Clinical Decision Aids

Format:

Web Page

DOI (1):

10.1001/jama.2020.2633

Keywords

2019 novel coronavirus

A comparison between COVID19 and influenza in 2020 in the U.S. so far. James W. Mold, MD, MPH

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No abstract available.

Author/s:

Livingston, E, Bucher, K, Rekito, A

Interim Estimates of 2019–20 Seasonal Influenza Vaccine Effectiveness — United States, February 2020

John Bayhi — Thu, 20 Feb 2020 18:58:45 +0000

Date Added:

February 20, 2020

Journal/Publication:

Morbidity and Mortality Weekly Report

Publisher:

Centers for Disease Control & Prevention / U.S. Department of Health and Human Services

Publication Date:

February 21, 2020

Issue:

Volume:

Pages:

177-182

URL:

Interim Estimates of 2019–20 Seasonal Influenza Vaccine Effectiveness — United States, February 2020

Type:

Public Health Announcements

Format:

Article

DOI (1):

10.15585/mmwr.mm6907a1

Keywords

influenza

Flu vaccines

effectiveness

The flu vaccine appears to be about 45% effective for preventing the flu this year. James W. Mold, MD, MPH

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What is already known about this topic?

Annual vaccination against seasonal influenza is recommended for all U.S. persons aged ≥6 months. Effectiveness of seasonal influenza vaccine varies by season.

What is added by this report?

According to data from the U.S. Influenza Vaccine Effectiveness Network on 4,112 children and adults with acute respiratory illness during October 23, 2019–January 25, 2020, the overall estimated effectiveness of seasonal influenza vaccine for preventing medically attended, laboratory-confirmed influenza virus infection was 45%.

What are the implications for public health practice?

Vaccination remains the best way to protect against influenza and its potentially serious complications. CDC continues to recommend influenza vaccination while influenza viruses are circulating in the community.

Author/s:

Dawood, FS, Chung, JR, Kim, SS, Zimmerman, RK, Nowalk, MP, Jackson, ML, Jackson, LA, Monto, AS, Martin, ET, Belongia, EA, McLean, HQ, Gaglani, M, Dunnigan, K, Foust, A, Sessions, W, DaSilva, J, Le, S, Stark, T, Kondor, RJ, Barnes, JR, Wentworth, DE, Brammer, L, Fry, AM, Patel, MM, Flannery, B

Oseltamivir plus usual care versus usual care for influenza-like illness in primary care: an open-label, pragmatic, randomised controlled trial

John Bayhi — Thu, 02 Jan 2020 19:26:04 +0000

Date Added:

January 2, 2020

Journal/Publication:

Lancet

Publisher:

Elsevier Inc.

Publication Date:

December 12, 2019

URL:

Oseltamivir plus usual care versus usual care for influenza-like illness in primary care: an open-label, pragmatic, randomised controlled trial

Type:

Clinical Research Results

Format:

Article

DOI (1):

10.1016/S0140-6736(19)32982-4

Keywords

PMID (1):

31839279

MeSH

Polymerase Chain Reaction

Europe

Large pragmatic clinical trial from Europe documenting impacts of treatment of influenza with Tamiflu. James W. Mold, MD, MPH

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BACKGROUND:

Antivirals are infrequently prescribed in European primary care for influenza-like illness, mostly because of perceived ineffectiveness in real world primary care and because individuals who will especially benefit have not been identified in independent trials. We aimed to determine whether adding antiviral treatment to usual primary care for patients with influenza-like illness reduces time to recovery overall and in key subgroups.

METHODS:

We did an open-label, pragmatic, adaptive, randomised controlled trial of adding oseltamivir to usual care in patients aged 1 year and older presenting with influenza-like illness in primary care. The primary endpoint was time to recovery, defined as return to usual activities, with fever, headache, and muscle ache minor or absent. The trial was designed and powered to assess oseltamivir benefit overall and in 36 prespecified subgroups defined by age, comorbidity, previous symptom duration, and symptom severity, using a Bayesian piece-wise exponential primary analysis model. The trial is registered with the ISRCTN Registry, number ISRCTN 27908921.

FINDINGS:

Between Jan 15, 2016, and April 12, 2018, we recruited 3266 participants in 15 European countries during three seasonal influenza seasons, allocated 1629 to usual care plus oseltamivir and 1637 to usual care, and ascertained the primary outcome in 1533 (94%) and 1526 (93%). 1590 (52%) of 3059 participants had PCR-confirmed influenza infection. Time to recovery was shorter in participants randomly assigned to oseltamivir (hazard ratio 1·29, 95% Bayesian credible interval [BCrI] 1·20-1·39) overall and in 30 of the 36 prespecified subgroups, with estimated hazard ratios ranging from 1·13 to 1·72. The estimated absolute mean benefit from oseltamivir was 1·02 days (95% [BCrI] 0·74-1·31) overall, and in the prespecified subgroups, ranged from 0·70 (95% BCrI 0·30-1·20) in patients younger than 12 years, with less severe symptoms, no comorbidities, and shorter previous illness duration to 3·20 (95% BCrI 1·00-5·50) in patients aged 65 years or older who had more severe illness, comorbidities, and longer previous illness duration. Regarding harms, an increased burden of vomiting or nausea was observed in the oseltamivir group.

INTERPRETATION:

Primary care patients with influenza-like illness treated with oseltamivir recovered one day sooner on average than those managed by usual care alone. Older, sicker patients with comorbidities and longer previous symptom duration recovered 2-3 days sooner.

FUNDING:

European Commission's Seventh Framework Programme.

Author/s:

Butler, CC, van der Velden, AW, Bongard, E, Saville, BR, Holmes, J, Coenen, S, Cook, J, Francis, NA, Lewis, RJ, Godycki-Cwirko, M, Llor, C, Chlabicz, S, Lionis, C, Seifert, B, Sundvall, PD, Colliers, A, Aabenhus, R, Bjerrum, L, Jonassen Harbin, N, Lindbæk M, Glinz, D, Bucher, HC, Kovacs, B, Radzeviciene Jurgute, R, Touboul Lundgren, P, Little, P, Murphy, AW, De Sutter, A, Openshaw, P, de Jong, MD, Connor, JT, Matheeussen, V, Ieven, M, Goossens, H, Verheij, TJ

Association of State Laws With Influenza Vaccination of Hospital Personnel

Tracy Ashby — Mon, 22 Apr 2019 05:00:00 +0000

Date Added:

April 22, 2019

Journal/Publication:

American Journal of Preventative Medicine

Publisher:

Elsevier Inc.

Publication Date:

April 16, 2019

URL:

Association of State Laws With Influenza Vaccination of Hospital Personnel

Type:

Community-Based Research Results

Format:

Article

DOI (1):

10.1016/j.amepre.2019.01.011

Keywords

PMID (1):

31003802

MeSH

delivery of health care

State laws and facility mandates increase rates of influence vaccination of health care workers. James W. Mold, MD, MPH.

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Introduction

Healthcare personnel influenza vaccination can reduce influenza illness and patient mortality. State laws are one tool promoting healthcare personnel influenza vaccination.

Methods

A 2016 legal assessment in 50 states and Washington DC identified (1) assessment laws: mandating hospitals assess healthcare personnel influenza vaccination status; (2) offer laws: mandating hospitals offer influenza vaccination to healthcare personnel; (3) ensure laws: mandating hospitals require healthcare personnel to demonstrate proof of influenza vaccination; and (4) surgical masking laws: mandating unvaccinated healthcare personnel to wear surgical masks during influenza season. Influenza vaccination was calculated using data reported in 2016 by short-stay acute care hospitals (n=4,370) to the National Healthcare Safety Network. Hierarchical linear modeling in 2018 examined associations between reported vaccination and assessment, offer, or ensure laws at the level of facilities nested within states, among employee and non-employee healthcare personnel and among employees only.

Results

Eighteen states had one or more healthcare personnel influenza vaccination-related laws. In the absence of any state laws, facility vaccination mandates were associated with an 11–12 percentage point increase in mean vaccination coverage (p<0.0001). Facility-level mandates were estimated to increase mean influenza vaccination coverage among all healthcare personnel by 4.2 percentage points in states with assessment laws, 6.6 percentage points in states with offer laws, and 3.1 percentage points in states with ensure laws. Results were similar in analyses restricted only to employees although percentage point increases were slightly larger.

Conclusions

State laws moderate the effect of facility-level vaccination mandates and may help increase healthcare personnel influenza vaccination coverage in facilities with or without vaccination requirements.

Author/s:

Lindley, Megan C., Mu, Yi, Hoss, Aila, Pepin, Dawn, Kalayil, Elizabeth J., van Santen, Katharina L., Edwards, Jonathan R., Pollock, Daniel A.

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)

Influenza Antivirals: Comparison

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

Date Added:

January 6, 2019

Publication Date:

January 4, 2019

Type:

Clinical Decision Aids

Format:

Article

Keywords

influenza

anti-influenza medication

MeSH

influenza, human

This is a table of information about the currently available anti-influenza meds.

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Table comparing different anti-influenza medications currently available.

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.

Baloxavir Marboxil for Uncomplicated Influenza in Adults and Adolescents

Tracy Ashby — Mon, 03 Dec 2018 06:00:00 +0000

Date Added:

October 30, 2019

Journal/Publication:

The New England Journal of Medicine

Publisher:

Massachusetts Medical Society

Publication Date:

September 6, 2018

Issue:

Volume:

379

Pages:

913-923

URL:

Baloxavir Marboxil for Uncomplicated Influenza in Adults and Adolescents

Type:

Clinical Research Results

Format:

Article

DOI (1):

10.1056/NEJMoa1716197

Keywords

baloxavir marboxil

oseltamivir

influenza

PMID (1):

30184455

MeSH

adolescent

Adult

Antiviral Agents/administration & dosage

Antiviral Agents/adverse effects

Antiviral Agents/therapeutic use

child

double-blind method

Endonucleases/antagonists & inhibitors

Intention to Treat Analysis

Kaplan-Meier Estimate

male

Middle Aged

oseltamivir/therapeutic use

Oxazines/administration & dosage

Oxazines/adverse effects

Pyridines/administration & dosage

Pyridines/adverse effects

Thiepins/admistration & dosage

Thiepins/adverse effects

Triazines/administration & dosage

Triazines/adverse effects

viral load

Virus Replication/drug effects

Young Adult

These RCTs of the new anti-viral agent, baloxavir marboxil (Zofluza), found that, when given within 48 hours of onset of symptoms, it relieves symptoms one day sooner than placebo (same as Tamiflu). Viral shedding is reduced more effectively though. Resistance appears to develop quickly. The single-dose treatment costs about $150. James W. Mold, MD, MPH

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BACKGROUND:

Baloxavir marboxil is a selective inhibitor of influenza cap-dependent endonuclease. It has shown therapeutic activity in preclinical models of influenza A and B virus infections, including strains resistant to current antiviral agents.

METHODS:

We conducted two randomized, double-blind, controlled trials involving otherwise healthy outpatients with acute uncomplicated influenza. After a dose-ranging (10 to 40 mg) placebo-controlled trial, we undertook a placebo- and oseltamivir-controlled trial of single, weight-based doses of baloxavir (40 or 80 mg) in patients 12 to 64 years of age during the 2016-2017 season. The dose of oseltamivir was 75 mg twice daily for 5 days. The primary efficacy end point was the time to alleviation of influenza symptoms in the intention-to-treat infected population.

RESULTS:

In the phase 2 trial, the median time to alleviation of influenza symptoms was 23.4 to 28.2 hours shorter in the baloxavir groups than in the placebo group (P<0.05). In the phase 3 trial, the intention-to-treat infected population included 1064 patients; 84.8 to 88.1% of patients in each group had influenza A(H3N2) infection. The median time to alleviation of symptoms was 53.7 hours (95% confidence interval [CI], 49.5 to 58.5) with baloxavir, as compared with 80.2 hours (95% CI, 72.6 to 87.1) with placebo (P<0.001). The time to alleviation of symptoms was similar with baloxavir and oseltamivir. Baloxavir was associated with greater reductions in viral load 1 day after initiation of the regimen than placebo or oseltamivir. Adverse events were reported in 20.7% of baloxavir recipients, 24.6% of placebo recipients, and 24.8% of oseltamivir recipients. The emergence of polymerase acidic protein variants with I38T/M/F substitutions conferring reduced susceptibility to baloxavir occurred in 2.2% and 9.7% of baloxavir recipients in the phase 2 trial and phase 3 trial, respectively.

CONCLUSIONS:

Single-dose baloxavir was without evident safety concerns, was superior to placebo in alleviating influenza symptoms, and was superior to both oseltamivir and placebo in reducing the viral load 1 day after initiation of the trial regimen in patients with uncomplicated influenza. Evidence for the development of decreased susceptibility to baloxavir after treatment was also observed. (Funded by Shionogi; JapicCTI number, 153090, and CAPSTONE-1 ClinicalTrials.gov number, NCT02954354 .).

Author/s:

Hayden, Frederick G., Sugaya, Norio, Hirotsu, Nobuo, Lee, Nelson, de Jong, Menno D., Hurt, Aeron C., Ishida, Tadashi, Sekino, Hisakuni, Yamada, Kota, Portsmouth, Simon, Kawaguchi, Keiko, Shishido, Takao, Arai, Masatsugu, Tsuchiya, Kenji, Uehara, Takeki, Watanabe, Akira, Baloxavir Marboxil Investigators Group

Checklist to Prepare Physicians’ Offices for Pandemic Influenza

Tracy Ashby — Sat, 27 Oct 2018 05:00:00 +0000

Date Added:

October 27, 2018

Publication Date:

July 1, 2015

Type:

Meta-analyses, Reviews, and Guidelines

Format:

Article

Keywords

MeSH

This is a checklist from the AAFP listing what primary care practices should do to prepare for flu season.

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American Academy of Family Physicians Checklist to Prepare Physicians' Offices for Pandemic Influenza.

Author/s:

American Academy of Family Physicians

Influenza (The Flu)

Tracy Ashby — Fri, 05 Oct 2018 05:00:00 +0000

Date Added:

October 5, 2018

Publication Date:

March 1, 2018

Type:

Patient Education Materials

Format:

Article

Keywords

influenza

symptoms

MeSH

influenza, human

This patient information handout on influenza was copied from the CDC website and lightly reformatted.

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Influenza information handout from the CDC.

Author/s:

Centers for Disease Control and Prevention (CDC)

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