Most Vaccine Side Effects Are Minor And Only Last A Day Or Two
Many people who receive vaccines have no side effects. For those that do, the side effects are usually very minor, like soreness, redness, or swelling where the vaccine was given, or a mild fever. These side effects usually only last a day or two. Some side effects are from the process of immunization, such as those related to fear of getting a needle .
Five Times Higher Rate With Short Dosing Interval
For the study, researchers from Public Health Ontario, the University of Toronto, and the nonprofit ICES analyzed data on 19,740,741 doses of mRNA COVID vaccine administered in the province from Dec 14, 2020when vaccines were first availableto Sep 4, 2021.
Ontario’s electronic reporting system revealed 297 cases of myocarditis or pericarditis among those vaccine recipients, or only about 15 cases per million vaccine doses.
Of the 297 cases, 228 occurred in male recipients, and the median age of affected patients was 24 years . Also, 207 of the cases occurred following the second vaccine dose.
Nearly all of the cases involved an emergency department visit, with 210 cases also requiring hospital admission. The number of hospitalizations was 87 for myocarditis, 33 for pericarditis, and 90 for people who had both conditions.
When the investigators focused solely on people who received their second dose during the period of enhanced passive surveillance , they found that the incidence of myocarditis or pericarditis was 62.5 cases per million doses after the second Moderna dose , compared with 29.0 cases per million doses for Pfizeror more than twice as high.
Men 18 to 24 years old had the highest rate: 299.5 cases per million doses after the second Moderna dose , compared with 59.2 cases per million doses for Pfizeror about five time higher with Moderna.
What’s Flu Activity Like This Season
In general, flu activity in the U.S. began to trend upward in late October and through December, the CDC reported.
That’s exactly what scientists had predicted that this year’s flu activity would eventually spike.After the country experienced historically low levels of flu during the 2020-2021 season , several studies have predicted that the flu could come roaring back this fall and winter, Live Science previously reported.
That’s because the U.S. population “missed the opportunity to establish or boost their immunity ” last season, which raises the concern that the flu could make a comeback as preventive measures for COVID-19 are lifted, according to the authors of a recent study on predicting flu activity, posted Aug. 30 to the preprint database medRxiv .
In October, the CDC began an investigation at the University of Michigan’s Ann Arbor campus, where there was a sudden spike in flu cases, Live Science previously reported. Most of these infections were caused by an H3N2 flu virus. This trend has since cropped up in data from across the U.S., as H3N2 appears to be the dominant strain circulating countrywide.
Even if flu activity is currently low in your community, you shouldn’t wait to get your flu shot. Flu activity could begin to increase at any time, and it takes about two weeks for people to develop antibodies against flu viruses after receiving their shot, the CDC says.
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Who Should Not Have The Flu Vaccine
Most adults can have the flu vaccine, but you should avoid it if you have had a serious allergic reaction to a flu vaccine in the past.
You may be at risk of an allergic reaction to the flu vaccine injection if you have an egg allergy. This is because some flu vaccines are made using eggs.
Ask a GP or pharmacist for a low-egg or egg-free vaccine.
If you’re ill with a high temperature, it’s best to wait until you’re better before having the flu vaccine.
Side Effects From Immunisation

Immunisations are safe and effective, although all medication can have unwanted side effects. You may experience minor side effects following vaccination. Most reactions are mild and go away quickly.
Common reactions to vaccination include:
- pain, redness, itching, swelling or burning where the needle was given
- mild fever that doesnt last long
These are generally mild and usually last for 12 days.
Common side effects for each vaccine are also listed on the Vaccines pages. If you have any concerns about potential side effects of vaccines, talk to your doctor or nurse.
In general, most children who have had a reaction to a vaccination can be safely re-vaccinated. Speak to your doctor for further advice. They may refer you to Immunisation specialist services for more testing or precautions before receiving further vaccines.
The Consumer Medicine Information available on the Therapeutic Goods Administration website also lists the side effects of each vaccine.
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Possible Side Effects From Vaccines
Any vaccine can cause side effects. For the most part these are minor and go away within a few days. Listed below are vaccines licensed in the United States and side effects that have been associated with each of them. This information is copied directly from CDCs Vaccine Information Statements , which in turn are derived from the Advisory Committee on Immunization Practices recommendations for each vaccine.
Remember, vaccines are continually monitored for safety, and like any medication, vaccines can cause side effects. However, a decision not to immunize a child also involves risk and could put the child and others who come into contact with him or her at risk of contracting a potentially deadly disease.
Headache And Other Aches And Pains
After your shot, you might have headaches or some achiness and pain in the muscles throughout your body. This also usually happens on the first day and goes away within two days. Taking pain relievers can help ease your discomfort.
Its controversial whether its safe to take acetaminophen or ibuprofen to treat these vaccine side effects.
Some research suggests that these medications might change or decrease how your body responds to the vaccine. One study involving children found that taking acetaminophen or ibuprofen didnt reduce the bodys response to the flu vaccine.
Other research is mixed. Its still unclear whether these medications should be avoided.
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Myths About The Flu Vaccine
Myth 1: Influenza is not serious so I dont need the vaccine
Fact: As many as 650 000 people a year can die of the flu. This only represents respiratory deaths, so the likely impact is even higher. Even healthy people can get the flu, but especially people whose immune systems are vulnerable. Most people will recover within a few weeks, but some can develop complications including sinus and ear infections, pneumonia, heart or brain inflammations.
Myth 2: The flu vaccine can give me the flu
Fact: The injected flu vaccine contains an inactivated virus that cannot give you influenza. If you feel achy or slightly feverish, it is a normal reaction of the immune system to the vaccine, and generally lasts only a day or two.
Myth 3: The flu vaccine can cause severe side effects
Fact: The flu vaccine is proven to be safe. Severe side effects are extremely rare. One in a million people may get Guillain-Barré Syndrome , which cause muscle weakness and paralysis.
Myth 4: I had the vaccine and still got the flu, so it doesnt work
Fact: Several flu viruses are circulating all the time, which is why people may still get the flu despite being vaccinated since the vaccine is specific to one strain. However, being vaccinated improves the chance of being protected from the flu. This is especially important to stop the virus affecting people with vulnerable immune systems.
Myth 5: I am pregnant so shouldnt get the flu vaccine
Where To Get The Flu Vaccine
You can have the NHS flu vaccine at:
- your GP surgery
- a pharmacy offering the service
- your midwifery service if you’re pregnant
- a hospital appointment
If you do not have your flu vaccine at your GP surgery, you do not have to tell the surgery. This will be done for you.
It’s important to go to your vaccination appointments unless you have symptoms of COVID-19.
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Signs Of A More Serious Reaction
“A very small percentage of people can have a true allergic reaction to the vaccine, including chest tightness, difficulty breathing, wheezing, facial or throat swelling and redness of the eyes,” Teague says. If you experience these symptoms, you should seek medical attention immediately. Teague says severe allergic reactions usually happen within a few hours of getting the flu shot.
Signs of a severe allergic reaction, according to the CDC, can include:
- Difficulty breathing
- Swelling around the eyes or lips
- Hives
How Is The Safety Of Flu Vaccines Monitored
CDC and the Food and Drug Administration closely monitor the safety of vaccines approved for use in the United States. CDC uses two primary systems to monitor the safety of flu vaccines:
People with egg allergies can receive any licensed, recommended age-appropriate influenza vaccine that is otherwise appropriate. People who have a history of severe egg allergy should be vaccinated in a medical setting, supervised by a health care provider who is able to recognize and manage severe allergic reactions. Two completely egg-free flu vaccine options are available: quadrivalent recombinant vaccine and quadrivalent cell-based vaccine.
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How To Book Your Appointment
If you’re eligible for a free flu vaccine, you can book an appointment at your GP surgery or a pharmacy that offers it on the NHS.
You may also get an invitation to get the vaccine, but you do not have to wait for this before booking an appointment.
Everyone who is eligible for the free flu vaccine will be able to get it.
GP surgeries and pharmacies get the flu vaccine in batches. If you cannot get an appointment straight away, ask if you can book an appointment for when more vaccines are available.
If you have an appointment for a COVID-19 booster vaccine at a GP surgery or pharmacy, you may also be offered a flu vaccine at the same time.
Do not delay booking your flu vaccine appointment so that you can get both vaccines together. Only some people will be offered both vaccines at the same time.
Correlation Is Not Causation

In an ideal situation, an adverse event would be directly linked to a vaccine using a specific lab test. For example, an early version of the polio vaccine, which used a weakened form of the virus to generate immunity, caused roughly one person to develop the disease for every 2.4 million doses given. The virus strain used in the vaccine could be isolated from spinal fluid in these cases, says Edwards, so it was clear that the vaccine had caused the disease.
But these kinds of test arent possible for most adverse events, either because there arent specific biomarkers to test for, or because such tests are impractical. At least initially, the events are only linked by their timing: a person receives a vaccine and then experiences the side effect at some point afterwards. This makes it particularly challenging to prove whether the adverse event was actually caused by the vaccine, Edwards says, especially when the reaction occurs days or weeks after the vaccination itself.
To investigate the link, researchers conduct studies to determine the rate of adverse events in vaccinated populations compared with the probability that they occur by chance in people who havent received the vaccine. They also need to determine the mechanism that could have caused the reaction.
A child being vaccinated against polio. An earlier version of the polio vaccine caused one person to develop the disease for every 2.4 million doses given.Credit: Farooq Khan/EPA/Shutterstock
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Choosing Not To Immunize Is The Riskier Choice
Some people choose not to immunize because theyre worried about the risk of possible side effects. But choosing not to immunize is the riskier choice. The risks from the diseases vaccines prevent are much greater than the risk of a vaccine side effect. If you choose not to immunize your child, its important to understand the risks and to know how to reduce the risk of your child getting a disease and spreading it to others. Learn more.
Myocarditis And The Covid
Since April 2021, some people have developed myocarditis and pericarditis after receiving the Pfizer-BioNTech or Moderna coronavirus vaccines in the United States, according to the U.S. Centers for Disease Control and Prevention . The problem occurs more often in adolescents and young adults, and in males.
Considering the hundreds of millions of COVID-19 vaccine doses that have been administered, these reports are very rare. The vast majority of myocarditis or pericarditis cases are mild and resolve quickly. Myocarditis is more likely to occur as a result of COVID-19 infection than as a side effect of the vaccines.
Seek medical attention right away if, within a few days of receiving the second injection of an mRNA COVID-19 vaccination , you or your child experience:
- Chest pain
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Pregnancy And Influenza Immunisation
Pregnant women are at increased risk of complications from the flu. The flu vaccine is strongly recommended and safe for pregnant women at any time during pregnancy. It can also be safely given while breastfeeding.
Flu vaccination of pregnant women also protects infants against the flu for the first 6 months after birth due to transplacental transfer of antibodies from the vaccinated woman to the unborn baby.
Is Getting Sick After Flu Shots Normal
Generally speaking, flu vaccinations are safe and do not lead to serious side effects. In rare cases, it may cause an allergic reaction. While these reactions can be life-threatening, the Immunisation Nursing team at Corporate Care have emergency protocols in place to deal with such situations.
Millions of Australians get flu jabs every year and do not experience any complications at all.
Once you receive the flu shot, it takes around two weeks to generate enough antibodies to fight off the flu strains found in the vaccine administered .
This immune response may cause mild flu-like symptoms that can often be alleviated with over the counter Paracetamol or Ibuprofen .
There’s no reason to avoid getting the flu shot because you think it’ll make you sick. We strongly recommend speaking with a healthcare professional to answer any of your concerns or question about the flu.
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Myth #: Antibiotics Can Fight The Flu If You Get It
Antibiotics only kill bacteria, but the flu is caused by a virus.
There are antiviral drugs that can fight flu infections, but they’ve only been shown to work when they’re given within 48 hours of the start of symptoms. “Most people, by the time they go to the doctor, they’re past the 48-hour mark,” said Dr. Dennis Cunningham, an infectious disease specialist at Nationwide Children’s Hospital in Columbus, Ohio.
For patients hospitalized with severe flu, the drugs may help, he said. But they aren’t a cure, and for most people who aren’t hospitalized, these drugs may only cut down on the duration of the flu by a day or two.
Table : Comparison Of Risks Associated With Influenza Disease And Inactivated Seasonal Influenza Vaccination
Risks associated with seasonal influenza infection |
Risks associated with inactivated seasonal influenza vaccination* |
---|---|
Common symptoms
|
Common adverse event
|
Possible complications
|
Rare adverse event |
Very rare adverse event
|
*Reported risks refer to inactivated influenza vaccines commonly used in organised immunisation programmes in the European Union. For details see Summary of Product Characteristics for each vaccine available on national regulatory agency websites.
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Rare Side Effects Of The Flu Nasal Spray Vaccine
As with all vaccines, there’s a very small chance of a severe allergic reaction . The overall rate of anaphylaxis after vaccination is around one in 900,000 .
Anaphylaxis is very serious but it can be treated with adrenaline. When it happens, it does so within a few minutes of the vaccination. Staff who give vaccinations have all been trained to spot and deal with anaphylactic reactions and children recover completely with treatment.
What Should I Know About The 2021

For starters, its important to know that its highly recommended that you get vaccinated against the flu even though last years flu season was mild, thanks, in large part, to many people masking, staying indoors, and taking other preventive measures to avoid the spread of COVID-19.
A minimal flu season last year doesnt mean were in the clear this year. In fact, weve already seen flu outbreaks this flu season, such as the massive outbreak at the University of Michigan campus. Dr. Agarwal says theres a possibility that outbreaks will continue throughout the flu season as people loosen up on illness-reducing behaviors like wearing face masks. And its important to remember that some people do end up with complications from the flu.
Flu viruses are always changing, so flu vaccine formulas are reviewed every year to best protect people against the viruses that are predicted to cause the most illness, according to the CDC. All of the vaccines available for the 2021-2022 flu season, whether theyre via nasal or needle administration, protect against the same four flu viruses circulating heavily right now.
According to the CDC, one vaccine isnt any better than the other, but if you have any questions about whether one might be best for you, then its always safest to talk to your doctor.
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