Can the Flu Vaccine Cause Paralysis? What Research Shows About Guillain-Barré Syndrome and Other Rare Reactions

Can the flu vaccine cause paralysis? Very rarely. Seasonal flu vaccines are linked to about one extra case of Guillain-Barré syndrome, a nerve disorder that can cause temporary weakness or paralysis, per million doses. Flu illness itself carries a much higher risk, about 17 extra cases per million flu-related medical visits in one large study. Large safety studies have not found that flu vaccines cause transverse myelitis, and acute flaccid myelitis in children has been linked mainly to a virus, not vaccines.

Stories of children or adults who became weak or paralyzed after a flu shot are frightening, and the families who share them are describing real suffering. When a serious illness follows a vaccine, it is natural to connect the two. Scientists take these reports seriously, and the U.S. vaccine safety system was built in part because of a real problem: the 1976 swine flu vaccine campaign was linked to a measurable increase in Guillain-Barré syndrome. This article explains which neurological conditions cause sudden weakness, what decades of research show about their links to flu vaccines and to flu itself, how families can get help if an injury occurs, and how to weigh the risks.

Which Conditions Cause Sudden Weakness or Paralysis?

Several rare neurological conditions can cause weakness or paralysis that develops over days. Guillain-Barré syndrome is an autoimmune disorder in which the immune system attacks the nerves outside the brain and spinal cord, usually causing weakness that starts in the legs and moves upward; most people recover over weeks to months, though some have lasting effects. Transverse myelitis is inflammation of a section of the spinal cord. Acute disseminated encephalomyelitis (ADEM) is inflammation of the brain and spinal cord, more common in children. Acute flaccid myelitis (AFM) affects the gray matter of the spinal cord and causes sudden limb weakness, mostly in children. All of these conditions can follow infections, and some cases have no identified trigger, which makes it hard to tell from a single case whether a recent vaccine played a role.

What Happened With the 1976 Swine Flu Vaccine?

In 1976, the U.S. government launched a mass vaccination campaign against a new swine flu strain. Reports of GBS after vaccination soon rose, and the program was suspended in December 1976. A 1979 analysis in the American Journal of Epidemiology by Lawrence Schonberger and colleagues reviewed 1,098 GBS cases reported nationwide and found that vaccinated adults had a significantly higher rate than unvaccinated adults in every age group. The estimated excess risk was just under one case per 100,000 vaccinations, concentrated within about five weeks after the shot. This episode is the main reason GBS is closely monitored for every flu vaccine since.

Do Today’s Seasonal Flu Vaccines Cause Guillain-Barré Syndrome?

If they do, the risk is very small. A 2015 meta-analysis in Vaccine by Luis Martín Arias and colleagues pooled 39 controlled observational studies published between 1981 and 2014. Across all flu vaccines, the relative risk of GBS was 1.41, meaning a 41 percent increase over a very low baseline. Pandemic vaccines showed a higher relative risk (1.84) than seasonal vaccines (1.22), and the seasonal result was only marginally significant. When the 2009 H1N1 pandemic vaccine was given to tens of millions of Americans, a 2013 meta-analysis in The Lancet by Daniel Salmon and colleagues, covering about 23 million vaccinated people, found about 1.6 extra GBS cases per million people vaccinated. Because GBS normally strikes about 1 to 2 people per 100,000 each year regardless of vaccination, an added risk of about 1 per million is difficult to detect and very small in absolute terms.

Is Flu Itself a Bigger Risk for Guillain-Barré Syndrome?

Yes, by a wide margin in the best direct comparison. A 2013 study in The Lancet Infectious Diseases by Jeffrey Kwong and colleagues used Ontario health records from 1993 to 2011 and identified 2,831 hospital admissions for GBS. The risk of GBS in the six weeks after a flu vaccine was 52 percent higher than in a later comparison period, equal to about 1 extra admission per million vaccinations. After a medical visit for influenza, the risk was nearly 16 times higher than the comparison period, equal to about 17 extra admissions per million flu-related visits. Because flu infection can trigger GBS, vaccination that prevents flu may prevent some GBS cases even as it may rarely cause others.

Do Flu Vaccines Cause Transverse Myelitis or ADEM?

Large studies have not found a link with flu vaccines. A 2016 study in Clinical Infectious Diseases by Roger Baxter and colleagues searched the Vaccine Safety Datalink, a network of health systems covering millions of Americans, for every case of transverse myelitis and ADEM after nearly 64 million vaccine doses. Only 7 cases of transverse myelitis and 8 of ADEM occurred in the 5 to 28 days after vaccination. There was no increased risk of transverse myelitis after any vaccine. For ADEM, the only possible signal was with the Tdap vaccine, based on two cases, with an estimated excess risk of no more than about 1 case per million doses; flu vaccines showed no increased risk.

What Causes Acute Flaccid Myelitis in Children?

Evidence points mainly to viruses, especially enterovirus D68. Acute flaccid myelitis drew national attention when U.S. cases spiked in 2014, 2016, and 2018, in late summer and fall. A 2018 analysis in The Lancet Infectious Diseases by Kevin Messacar and colleagues found that rises in enterovirus D68 circulation coincided in time and place with AFM outbreaks, and applied standard criteria for causation to conclude the evidence supports a causal link, while noting gaps. Most children with AFM had a respiratory illness or fever before weakness began. The seasonal timing of AFM can overlap with flu vaccination season, which may lead families to suspect a vaccine, but investigations have not found vaccines to be the cause.

How Dangerous Is Flu for Children?

More dangerous than many parents realize. A 2025 CDC report in MMWR by Katie Reinhart and colleagues found that 280 U.S. children died from flu-associated illness during the 2024–25 season, the most in any season since reporting began in 2004 apart from the 2009–10 pandemic. The median age at death was 7, and 56 percent had an underlying condition, most often a neurological disorder, so many of the children who died had no reported underlying condition. Among children eligible for vaccination with known status, 89 percent were not fully vaccinated. That season also brought reports of influenza-associated encephalopathy, including acute necrotizing encephalopathy, a severe brain complication of flu itself. Flu, in other words, can injure a child’s nervous system directly, beyond the fever and cough most parents expect.

What Should Families Do if They Suspect a Vaccine Injury?

Seek medical care quickly for any new weakness, tingling, trouble walking, difficulty breathing or swallowing, or loss of bladder control, whether or not a vaccine was recent; GBS can worsen over days and sometimes affects breathing, and early hospital treatment with immunoglobulin or plasma exchange can help. Report the event to the Vaccine Adverse Event Reporting System (VAERS), which anyone can do. In the United States, the National Vaccine Injury Compensation Program covers seasonal flu vaccines, and GBS beginning 3 to 42 days after a seasonal flu vaccine is listed as a table injury, which simplifies claims. Our article on vaccine injury compensation explains how the program works.

What Else Can Trigger Guillain-Barré Syndrome?

Infections are the most common trigger. About two-thirds of people with GBS report an infection in the weeks before symptoms begin, most often a respiratory or digestive illness. Campylobacter jejuni, a bacterium often spread through undercooked poultry, is one of the best-documented triggers. Influenza, cytomegalovirus, Epstein-Barr virus, Zika virus, and COVID-19 have also been linked to GBS, and it can occasionally follow surgery. In many cases no trigger is found. Because infections are so often involved, preventing them through food safety, hygiene, and vaccination can reduce the overall burden of GBS.

How Is Guillain-Barré Syndrome Treated, and Do People Recover?

GBS is treated in the hospital, often with intravenous immunoglobulin or plasma exchange, which can shorten the illness when started early. Doctors monitor breathing closely because roughly 20 to 30 percent of patients need help breathing at some point. Most people reach their weakest point within about four weeks and then gradually improve over weeks to months. Many recover fully or nearly so, but a minority have lasting weakness, numbness, or fatigue, and a small percentage die, usually from breathing or heart complications. Physical and occupational therapy play a large role in recovery. Children tend to recover more completely than adults.

Why Do Some Families Feel Unheard?

When a child becomes seriously ill soon after a vaccine, families understandably want answers, and being told that a link is unlikely can feel dismissive. Population studies describe risks across millions of people; they cannot always say what happened in one child. Good communication acknowledges the illness, explains what is known and unknown, ensures the event is reported and investigated, and points families to compensation programs when appropriate. Vaccine safety depends on public trust, and listening carefully to families who report problems is part of how rare risks, such as the GBS signals in 1976 and 2009, were identified in the first place.

Who Should Be Cautious About Flu Vaccines?

A history of GBS within six weeks of a previous flu vaccine is considered a precaution, and such people should discuss the benefits and risks with their doctor; some may choose to skip future flu vaccines, especially if they are not at high risk from flu. People who have had a severe allergic reaction to a previous flu vaccine should not receive that type again. A history of GBS unrelated to vaccination is not usually a reason to avoid flu vaccines, though it is worth discussing. For most people, including those with chronic illnesses that raise their risk from flu, the benefits of vaccination outweigh the small risks.

How Do the Risks Compare?

Condition	Link to flu vaccine	Link to infection
Guillain-Barré syndrome	About 1–2 extra cases per million doses	About 17 extra cases per million flu visits
Transverse myelitis	No increased risk found in 64 million doses	Can follow various infections
ADEM	No increased risk found for flu vaccines	Often follows viral infections
Acute flaccid myelitis	Not linked to vaccines	Strongly linked to enterovirus D68
Influenza encephalopathy	Not applicable	A direct complication of flu

Why Does Timing Make Vaccines Seem to Blame?

Millions of people get flu shots each fall, and some will develop unrelated illnesses in the following weeks purely by chance. If GBS strikes about 1 to 2 people per 100,000 each year, thousands of cases would be expected in any season, and some will inevitably occur shortly after a vaccine. That is why researchers use designs such as self-controlled studies, which compare a person’s risk shortly after vaccination with their own risk at other times, to separate coincidence from cause. These methods detected the small GBS signal after the 1976 and 2009 vaccines, showing the safety system can find rare problems when they exist.

How Well Does the Flu Vaccine Protect Children?

Protection is partial but meaningful. The CDC estimates that flu vaccines typically reduce the risk of medical visits for flu by about 40 to 60 percent in seasons when the vaccine is well matched to circulating viruses, with lower effectiveness in poorly matched years. Even when vaccinated people catch flu, studies suggest they are less likely to be hospitalized, admitted to intensive care, or die. Children under 9 receiving flu vaccine for the first time need two doses at least four weeks apart to be fully protected, which is one reason many children counted as “not fully vaccinated” had received only one dose. Vaccination of family members and caregivers also helps protect infants under 6 months, who are too young to be vaccinated and had the highest flu death rate in 2024–25.

How Is Flu Vaccine Safety Monitored?

Several systems watch for rare problems every season. VAERS collects reports from anyone, which makes it sensitive to new signals but unable to prove that a vaccine caused an event, because reports include coincidences and are not verified. The Vaccine Safety Datalink links the medical records of millions of patients in several health systems, allowing researchers to compare rates of conditions such as GBS in vaccinated and unvaccinated people, or in the same people at different times. The FDA runs additional monitoring through insurance and Medicare data. These overlapping systems detected the small GBS increase with the 2009 pandemic vaccine within months, which supports confidence that a larger risk would not go unnoticed.

Do Different Types of Flu Vaccine Carry Different Risks?

The data so far show similar, very low GBS risks across vaccine types. In the 2015 meta-analysis, adjuvanted pandemic vaccines, which contain an ingredient that strengthens the immune response, did not carry a higher GBS risk than non-adjuvanted ones. High-dose and adjuvanted vaccines used for older adults have been monitored closely, as described in our article on the high-dose flu vaccine. Nasal spray vaccine, which uses a weakened live virus, is an option for some healthy children and adults aged 2 to 49 and has its own list of people who should not receive it. People with concerns about a particular type can discuss alternatives with their clinician.

How Can Parents Make an Informed Decision?

Consider both sides of the risk. The chance that a flu vaccine causes GBS is around one in a million, while flu sends hundreds of thousands of Americans to the hospital in a typical season and killed 280 children in 2024–25. Talk with your child’s doctor about any personal or family history that matters, such as previous reactions or GBS after a vaccine. Ask what symptoms to watch for after vaccination and after flu illness. If your child does get sick with flu, early antiviral treatment, especially for children under 5 or with chronic conditions, reduces the risk of complications. Families who have experienced a possible vaccine injury deserve support, medical follow-up, and access to compensation, and their reports help keep the safety system working.

Common Myths

“Flu shots often cause paralysis.” The estimated added GBS risk is about one per million doses.

“Getting the flu is safer than the vaccine.” Flu illness carries a much higher GBS risk, plus other serious complications.

“Any illness after a vaccine was caused by it.” Rare conditions also occur by chance; careful studies are needed to tell the difference.

“Acute flaccid myelitis is a vaccine reaction.” Evidence links AFM mainly to enterovirus D68.

“Vaccine injuries are ignored.” GBS after flu vaccination is a listed injury in the federal compensation program.

Key Terms

Guillain-Barré syndrome (GBS): An autoimmune disorder that damages peripheral nerves and can cause weakness or paralysis.

Transverse myelitis: Inflammation across a segment of the spinal cord.

ADEM: Acute disseminated encephalomyelitis, widespread inflammation of the brain and spinal cord.

Acute flaccid myelitis: A rare condition causing sudden limb weakness, mostly in children.

Self-controlled study: A design comparing a person’s risk after an exposure with their own risk at other times.

The Bottom Line

Flu vaccines can very rarely trigger Guillain-Barré syndrome, at a rate of roughly one to two extra cases per million doses, a risk first identified after the 1976 swine flu campaign and monitored closely ever since. Flu infection itself carries a far higher GBS risk and causes other neurological complications, and the 2024–25 season killed 280 U.S. children. Large studies have not linked flu vaccines to transverse myelitis or ADEM, and acute flaccid myelitis is tied mainly to enterovirus D68. People with GBS after a previous flu shot should talk with their doctor, and anyone with new weakness should seek care promptly.

Frequently Asked Questions

Can a flu shot cause Guillain-Barré syndrome?

Rarely. Studies estimate about one to two extra cases of Guillain-Barré syndrome per million flu vaccine doses, usually within six weeks of vaccination. The risk was higher with the 1976 swine flu vaccine, at just under one per 100,000. Flu infection itself carries a much greater GBS risk, so for most people vaccination reduces overall risk.

Is GBS more likely from the flu or the flu vaccine?

From the flu. An Ontario study of 2,831 GBS hospital admissions over almost two decades found about 1 extra admission per million vaccinations, compared with about 17 extra admissions per million medical visits for influenza. Influenza is a known trigger of GBS, along with other infections such as Campylobacter food poisoning.

Can the flu vaccine cause paralysis in children?

Serious neurological reactions to flu vaccines in children are extremely rare. A Vaccine Safety Datalink study of nearly 64 million vaccine doses found no link between vaccines and transverse myelitis and no increased ADEM risk with flu vaccines. Acute flaccid myelitis in children has been linked mainly to enterovirus D68. Flu itself can cause serious brain complications in children.

What are the warning signs of Guillain-Barré syndrome?

Early signs include tingling or weakness starting in the feet or legs and spreading upward, difficulty walking or climbing stairs, facial weakness, and, in severe cases, trouble breathing or swallowing. Symptoms usually develop over days. Anyone with these signs should seek medical care urgently, since early treatment and monitoring of breathing are important.

Can I get compensation for a flu vaccine injury?

In the United States, seasonal flu vaccines are covered by the National Vaccine Injury Compensation Program. Guillain-Barré syndrome beginning 3 to 42 days after a seasonal flu vaccine is listed as a table injury, which simplifies the claims process. Families should also report suspected reactions to VAERS so they can be investigated.

References

1. Schonberger LB, Bregman DJ, Sullivan-Bolyai JZ, et al. Guillain-Barre syndrome following vaccination in the National Influenza Immunization Program, United States, 1976–1977. American Journal of Epidemiology. 1979;110(2):105–123. PMID 463869
2. Martín Arias LH, Sanz R, Sáinz M, et al. Guillain-Barré syndrome and influenza vaccines: a meta-analysis. Vaccine. 2015;33(31):3773–3778. PMID 25999283
3. Salmon DA, Proschan M, Forshee R, et al. Association between Guillain-Barré syndrome and influenza A (H1N1) 2009 monovalent inactivated vaccines in the USA: a meta-analysis. Lancet. 2013;381(9876):1461–1468. PMID 23498095
4. Kwong JC, Vasa PP, Campitelli MA, et al. Risk of Guillain-Barré syndrome after seasonal influenza vaccination and influenza health-care encounters: a self-controlled study. Lancet Infectious Diseases. 2013;13(9):769–776. PMID 23810252
5. Baxter R, Lewis E, Goddard K, et al. Acute demyelinating events following vaccines: a case-centered analysis. Clinical Infectious Diseases. 2016;63(11):1456–1462. PMID 27585798
6. Messacar K, Asturias EJ, Hixon AM, et al. Enterovirus D68 and acute flaccid myelitis: evaluating the evidence for causality. Lancet Infectious Diseases. 2018;18(8):e239–e247. PMID 29482893
7. Reinhart K, Huang S, Kniss K, et al. Influenza-associated pediatric deaths: United States, 2024–25 influenza season. MMWR Morbidity and Mortality Weekly Report. 2025;74(36):565–569. PMID 40996933

Last updated: October 10, 2026