Influenza vaccine updates 2026

The Flu Vaccine: A Balanced Conversation About Risk, Benefit, and Informed Consent

Every fall, the public hears a familiar message: influenza is dangerous, tens of thousands of people die from it each year, and the flu vaccine is the single best way to protect yourself, your family, and your community.

There is truth in that message. Influenza can cause serious illness. It can contribute to hospitalization and death, particularly in people with advanced age, frailty, chronic illness, immune compromise, pregnancy, or complex medical conditions. Seasonal flu vaccination can reduce the risk of laboratory-confirmed influenza, and in some populations and seasons may reduce serious outcomes.

But the public message is often more certain and less nuanced than the evidence itself.

Informed consent does not mean convincing everyone to refuse a vaccine. It also does not mean asking people to accept a recommendation without understanding the size of the likely benefit, the limits of the research, the uncertainty in mortality statistics, and the difference between a healthy child, a healthy working-age adult, and a medically fragile nursing-home resident.

A balanced conversation begins with the actual numbers.

What Does “Flu Death” Mean?

Many clinicians were trained with a familiar statistic: 36,000, 60,000, or more Americans die from influenza each year.

Most people hear that as a direct count of people with laboratory-confirmed influenza who died from flu itself. That is not what the larger seasonal figures represent.

CDC’s higher seasonal influenza mortality figures are model-based estimates of influenza-associated deaths. CDC uses surveillance data, adjustment factors, and statistical methods to estimate the broader burden of deaths in which influenza may have contributed. CDC defines flu-related deaths as those in which influenza was “likely a contributor,” not necessarily the primary cause of death.[cdc][cdc]

Influenza can contribute to a cascade that includes viral or bacterial pneumonia, respiratory failure, sepsis, a heart attack, stroke, heart failure, worsening COPD, or decompensation of other chronic disease. In many cases, especially among frail older adults, it may be impossible to identify one single cause with certainty.

A model can be useful for estimating population burden. But a modeled influenza-associated mortality estimate is not the same thing as a direct count of laboratory-confirmed influenza deaths or death certificates listing influenza as the underlying cause.

That distinction should be made clear whenever mortality numbers are used to motivate a medical intervention.

Influenza and Pneumonia Are Different Measures

Another source of confusion is the longstanding combined category “influenza and pneumonia.”

CDC’s National Center for Health Statistics currently lists 48,139 deaths in the broad influenza-and-pneumonia category. CDC has also reported 1,153,761 deaths in the influenza-and-pneumonia category between 1999 and 2018, averaging 57,688 per year.[cdc][cdc]

But this category includes all forms of pneumonia, not just pneumonia caused by influenza.

Pneumonia can be bacterial, aspiration-related, hospital-acquired, fungal, caused by RSV, caused by COVID-19, or caused by other viruses. A person may die from pneumonia during flu season without ever having influenza. Influenza may contribute to some pneumonia deaths, but it is not accurate to assume every pneumonia death is an influenza death.

ICD-10 coding distinguishes influenza from pneumonia. Influenza deaths use codes J09 through J11; pneumonia deaths use codes J12 through J18.[cdc][kff]

When someone says, “60,000 people die from flu each year,” it is reasonable to ask:

• Is that a count of laboratory-confirmed influenza deaths?

• Is it death certificates specifically coded as influenza?

• Is it the broader influenza-and-pneumonia category?

• Or is it a modeled estimate of deaths in which influenza may have contributed?

Those categories are not interchangeable.

Models Can Help, But They Have Limits

CDC’s seasonal flu-burden estimates are created from surveillance data, with adjustments for testing practices, under-detection, and extrapolation from selected surveillance networks to the national population.[cdc][cdc]

This may be an appropriate way to estimate trends. But it necessarily involves assumptions.

A model cannot determine with certainty whether influenza caused the death of a particular person. It cannot perfectly separate influenza from other respiratory viruses, bacterial infections, or the complications of chronic illness. It also cannot fully resolve whether a person would have died at that time without influenza exposure.

This matters because large estimates can take on a life of their own. A model-based public-health estimate becomes a headline, then a talking point, then an unquestioned clinical fact.

Patients deserve to know whether they are hearing a direct count or a modeled estimate.

My Clinical Perspective

In 26 years of practicing family medicine, including approximately five years of inpatient training and clinical practice, I have never personally cared for a patient whose death was clearly and directly attributable to influenza.

I know of one influenza-associated death: the aunt of one of my patients, a nursing-home resident who tested positive for influenza about one month after receiving a flu vaccine. She was not my patient.

This is not a national mortality study, and it is not offered as one. It is an observation from a physician who has cared for patients and families across decades.

In routine outpatient and family medicine, straightforward deaths from influenza alone are rarely encountered. Severe winter respiratory deaths are more often multifactorial. They tend to occur in people with advanced age, dementia, frailty, institutional exposure, chronic lung disease, cardiovascular disease, diabetes, immune compromise, neurologic disease, aspiration risk, or a cascade involving pneumonia and sepsis.

Influenza may be part of that cascade. But it is not always possible to say influenza was the sole or even primary cause of death.

What the Vaccine Does in Healthy Adults

Influenza vaccines are not useless. The question is what they reliably do and for whom.

The 2018 Cochrane review of injected influenza vaccines in healthy adults found that vaccination probably reduced laboratory-confirmed influenza from about 2.3% to 0.9%. That is an absolute risk reduction of approximately 1.4 percentage points.

In practical terms, about 71 healthy adults would need vaccination to prevent one confirmed influenza case in the trial settings.[pmc.ncbi.nlm.nih][cochrane]

The same review estimated a reduction in influenza-like illness from about 21.5% to 18.1%. That means roughly 29 healthy adults would need vaccination to prevent one episode of influenza-like illness.[pmc.ncbi.nlm.nih][cochrane]

Those are real benefits, but modest ones on average. The Cochrane review described injected influenza vaccines as probably having a small protective effect in healthy adults. Evidence for a reduction in hospitalization in that healthy-adult trial population was low-certainty.[pmc.ncbi.nlm.nih][cochrane]

That does not prove there is no hospitalization benefit for higher-risk groups. It does mean that healthy adults should be given realistic expectations rather than promises.

What CIDRAP Found

CIDRAP’s Comprehensive Influenza Vaccine Initiative published The Compelling Need for Game-Changing Influenza Vaccines in 2012. The report concluded that existing standard influenza vaccines had moderate effectiveness in healthy, non-elderly adults and young children but did not demonstrate consistent protection across all age groups.[cidrap.umn][cidrap.umn]

The report estimated approximately 59% protection from standard trivalent inactivated influenza vaccine in healthy adults ages 18 through 64. It found a lack of consistent evidence of protection in children ages 2 through 17 and in adults age 65 and older in the evidence reviewed at that time.[cidrap.umn][cidrap.umn]

For live attenuated influenza vaccine, often called the nasal-spray vaccine, the report cited pooled protection of approximately 83% in children ages 6 months through 7 years.[cidrap.umn][cidrap.umn]

This report is now more than a decade old and does not settle the question for every current product or every season. But it illustrates an important reality: flu-vaccine effectiveness is not steady, universal, or interchangeable across age groups.

Healthy Children and Severe Outcomes

The 2018 Cochrane review of influenza vaccines in healthy children found that vaccination can reduce laboratory-confirmed influenza and influenza-like illness.[pmc.ncbi.nlm.nih]

For inactivated vaccines, the review found a reduction in laboratory-confirmed influenza from 30% to 11% in the trials assessed. It also found a probable reduction in influenza-like illness from 28% to 20%.[pmc.ncbi.nlm.nih]

But the review did not find convincing evidence from the available trials that vaccination reduced mortality, hospital admissions, serious complications, or community transmission in healthy children.[pmc.ncbi.nlm.nih]

This does not prove that flu vaccination cannot reduce severe outcomes in children. Hospitalization and death are rare, and many trials are too small to measure rare outcomes confidently. It does mean that prevention of laboratory-confirmed influenza should not automatically be presented as direct randomized-trial proof that vaccination prevents hospitalization and death in every healthy child.

That distinction matters when school-based vaccine programs are presented as a universally urgent intervention.

The Asthma and Hospitalization Study

A 2012 case-control study by Joshi and colleagues examined children ages 6 months to 18 years from 1999 through 2007 and evaluated whether trivalent inactivated influenza vaccine, or TIV, protected against influenza-related hospitalization.

The study found an association between prior TIV vaccination and higher odds of influenza-related hospitalization. The reported odds ratio was 3.67, with a 95% confidence interval of 1.6 to 8.4. The association remained significant when the researchers analyzed children by asthma status. The authors concluded that TIV did not show protection against influenza-related hospitalization in the pediatric participants, particularly among children with asthma.[pubmed.ncbi.nlm.nih]

The authors wrote:

“TIV did not provide any protection against hospitalization in pediatric subjects, especially children with asthma. On the contrary, we found a threefold increased risk of hospitalization in subjects who did get the TIV vaccine.”[pubmed.ncbi.nlm.nih]

This is a finding parents and clinicians deserve to know exists.

It is also essential to understand what it does and does not prove. The study was retrospective and case-control, not randomized. It cannot establish that vaccination caused hospitalization. Children with more severe asthma, higher health-care use, more frequent clinician visits, or greater underlying respiratory risk may have been more likely to receive the vaccine and also more likely to be hospitalized. This is known as confounding by indication.

A later systematic review of influenza vaccination in people with asthma found that the overall body of evidence more often suggested benefit, including a pooled estimate of 45% vaccine effectiveness against laboratory-confirmed influenza in two test-negative-design studies. The authors also noted limitations in the evidence base.[pmc.ncbi.nlm.nih][pubmed.ncbi.nlm.nih]

Both findings belong in an informed-consent conversation. The evidence is not as simple as “vaccination always protects children with asthma,” and the Joshi study does not prove that vaccination causes hospitalization.

A Randomized Trial and Other Respiratory Viruses

In 2012, Cowling and colleagues published a randomized trial involving 115 children who received either trivalent inactivated influenza vaccine or placebo.

During nine months of follow-up, children who received the inactivated vaccine had a higher rate of virologically confirmed infection with non-influenza respiratory viruses. The reported relative risk was 4.40, with a 95% confidence interval of 1.31 to 14.8. When additional confirmed infections were included, the relative risk was 3.46, with a 95% confidence interval of 1.19 to 10.1.[pubmed.ncbi.nlm.nih][pmc.ncbi.nlm.nih]

The viruses detected included rhinoviruses and coxsackie or echoviruses. The researchers discussed a possible phenomenon sometimes called virus interference: natural influenza infection may temporarily activate nonspecific immune responses that affect susceptibility to other respiratory viruses.[pubmed.ncbi.nlm.nih][pmc.ncbi.nlm.nih]

At the same time, the study did not show a statistically significant difference between groups in all acute respiratory illness or febrile acute respiratory illness. It was small, and its confidence intervals were wide.[pmc.ncbi.nlm.nih]

This study does not prove that flu vaccination makes children broadly more susceptible to respiratory infections. It does raise a legitimate question that warrants further investigation, and it shows why one should not claim that all respiratory outcomes move in a single predictable direction.

What About Getting Vaccinated Every Year?

Annual flu vaccination is often presented as though each dose simply adds protection. The research suggests a more complex picture.

Studies of repeated vaccination have found that prior-season vaccination can influence current-season effectiveness. The effect appears to depend on the viral subtype, the match between vaccine and circulating strains, a person’s prior infection history, and the specific season.

Canada’s National Advisory Committee on Immunization reviewed evidence on repeated seasonal vaccination and concluded that there was no consistent overall difference in effectiveness between repeated vaccination and current-season-only vaccination. But it also identified seasons in which repeated vaccination was associated with lower effectiveness, particularly against influenza A(H3N2).[canada]

During the 2014 to 2015 season, when a drifted A(H3N2) virus circulated, pooled evidence found that repeated vaccination was 54% less effective against A(H3N2) than current-season-only vaccination. The confidence interval ranged from 20% to 88% lower effectiveness.[canada]

These observations do not show that repeated vaccination is harmful in every season or for every person. They do challenge the simplistic claim that annual vaccination always creates the same, or greater, protection.

A 2011 immunology study by Bodewes and colleagues also found that children who received annual influenza vaccination developed vaccine-specific antibody and CD4 T-cell responses, but did not show the age-related increase in influenza-specific CD8 T-cell responses observed in unvaccinated children. The study involved children with cystic fibrosis and examined immune responses, not clinical outcomes such as hospitalization or death.[pubmed.ncbi.nlm.nih][journals.asm]

The researchers concluded that annual vaccination was effective against seasonal influenza but could hamper the development of virus-specific CD8 T-cell responses.[pubmed.ncbi.nlm.nih][journals.asm]

This does not establish that annual vaccination weakens a child’s immune system or makes future pandemic illness worse. It does raise an important scientific question about how repeated strain-specific vaccination shapes broader immune memory over time.

A Clarification About the Military Study and COVID-19

Some people have cited a military study as evidence that flu vaccination increases the risk of COVID-19. That claim is inaccurate.

The frequently cited Department of Defense study examined respiratory viruses during the 2017 to 2018 influenza season, before SARS-CoV-2 existed. It did not study COVID-19. It included seasonal coronaviruses that cause common-cold illnesses, which are different from SARS-CoV-2. Its overall conclusion found little to no evidence that influenza vaccination caused broad viral interference.[factcheck]

The study should not be used as evidence that flu vaccination increases COVID-19 risk.

Who Is Most Likely to Benefit?

Risk from influenza is not evenly distributed.

Potential benefit may be most important for:

• Frail older adults, especially nursing-home residents

• People with significant chronic heart or lung disease

• People with serious immune compromise

• People with major neurologic conditions or disability

• Pregnant people

• Very young infants

• Children and adults with complex chronic medical conditions

• People who live with or care for medically fragile family members

CDC recommends annual influenza vaccination for everyone age 6 months and older without a contraindication.[cdc]

That is a population-level recommendation. It does not mean that a healthy 10-year-old child, a healthy 35-year-old adult, and a medically fragile 86-year-old nursing-home resident have the same risk of severe illness or receive the same absolute benefit.

A universal policy may be administratively simple. Good medicine still requires individual context.

Questions for Public Health

When public funds support school vaccine clinics, mobile vaccination programs, or broad county messaging, officials should be transparent about the goal.

Is the goal to reduce:

• Laboratory-confirmed influenza?

• Missed school or work?

• Outpatient visits?

• Community transmission?

• Hospitalization?

• ICU admission?

• Death?

These are different objectives. The evidence for each outcome is different. The expected benefit differs dramatically according to a person’s age, health status, exposure, and baseline risk.

The appropriate response to this complexity is not fear, coercion, or dismissal of questions. It is better communication.

What Informed Consent Looks Like

A balanced influenza-vaccine discussion should include:

• A person’s age, health, pregnancy status, immune status, and chronic conditions

• Their baseline risk of serious complications from influenza

• Their work, household, and contact with medically fragile people

• The difference between reducing influenza infection and preventing severe outcomes

• The difference between direct mortality counts and modeled influenza-associated mortality

• The fact that vaccine effectiveness varies by season, subtype, and vaccine match

• The evidence for benefits and limitations in their age and risk group

• Common side effects and the importance of continued safety surveillance

• Their prior experience with influenza and vaccination

• Their personal values and tolerance for uncertainty

The Bottom Line

Influenza can cause serious illness. Vaccines can reduce the risk of influenza illness, though the magnitude of benefit is variable and depends on the person, the season, and the outcome being measured.

The larger annual flu-mortality figures commonly used in public messaging are model-based influenza-associated mortality estimates, not direct counts of confirmed influenza deaths. The combined influenza-and-pneumonia category is not equivalent to influenza-specific mortality. In healthy adults, average vaccine benefit is modest. In healthy children, evidence for reduced influenza illness is stronger than randomized-trial evidence for preventing rare severe outcomes. Some studies have raised important questions about asthma, hospitalization, non-influenza respiratory infections, and repeated annual vaccination.

None of this requires a person to reject all influenza vaccines.

It does require medicine and public health to speak with more humility, more precision, and more respect for individual risk.

Informed consent is not telling someone what conclusion they must reach. It is giving them the actual evidence, the actual uncertainties, and the dignity to weigh those facts in the context of their own health and family.