Variability Of Influenza Virus
The influenza A and B virus genome is composed of eight negative-sense RNA segments. The virus particle consists of a host-derived lipid envelope embedded with 3 or 4 glycoproteins surrounding the ribonucleoprotein complex and the polymerase proteins . The major influenza virus surface glycoproteins are hemagglutinin , neuraminidase , and, in smaller proportions, matrix protein 2 . Influenza B virus has an additional NB protein. Matrix protein 1 and nucleoprotein are associated with viral RNA and are important for viral assembly as well as budding, while the polymerase proteins are important for viral genome replication . HA and NA are the major antigenic proteins and are used to further classify influenza A viruses into multiple subtypes. Sixteen HA and 9 NA influenza A virus subtypes that are antigenically distinct have been identified, with the possible addition of a new subtype, H17, identified recently . Currently, lineages of H1 and H3 viruses circulate endemically in humans. Only a single subtype of influenza B virus has been identified, although two distinct antigenic lineages have evolved over time and cocirculate at variable levels in humans.
What Are The Different Types Of Flu
There are three types of flu viruses: A, B, and C. Type A and B cause the annual influenza epidemics that have up to 20% of the population sniffling, aching, coughing, and running high fevers. Type C also causes flu however, type C flu symptoms are much less severe.
The flu is linked to between 3,000 and 49,000 deaths and 200,000 hospitalizations each year in the United States. The seasonal flu vaccine was created to try to avert these epidemics.
Influenza Vaccines And Covid
- Why is it more important this year than ever to get vaccinated against influenza?
- Getting an influenza vaccine is more important than ever this year to protect yourself and the people around you from influenza and to help reduce the strain on our overstretched health care system responding to the COVID-19 pandemic. The symptoms of COVID-19 and influenza can be similar and make people sick enough to go to the hospital. By getting your influenza vaccine, you can help the health care system keep resources available to help those with COVID-19. In addition, last years low influenza rates mean our immunity against influenza is lower than usual. This makes getting your influenza vaccine this year more important than ever to protect yourself, your community, and our overstretched health care system.
- How can I tell if I have influenza or if I have COVID-19?
- Influenza and COVID-19 have similar symptoms, so it may be hard to tell the difference based on symptoms alone. It is best to confirm your COVID-19 diagnosis with a test and follow COVID-19 prevention measures to help keep others safe. Influenza and COVID-19 are both contagious respiratory illnesses but are caused by different viruses. COVID-19 seems to spread more easily than influenza and can cause more serious illnesses in some people. In addition, people with COVID-19 can take longer to show symptoms and can be contagious for longer than those with influenza.
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Variation On The Conventional
With the well-accepted limitations and deficiencies in the current influenza vaccine system, substantial resources have been spent trying to improve it. The improvements that are most advanced, many of which are already in use, are those that contribute incremental, but important, advances to the current TIV and LAIV platforms.
Southern Hemisphere Recommended Strains

The following is a list of WHO recommended strains for the southern hemisphere influenza season.
SH winter season | |
---|---|
A/California/7/2009 pdm09-like virus | A/Perth/16/2009 -like virus |
A/Texas/50/2012 -like virus | B/Brisbane/60/2008-like virus |
2021 cell- or recombinant-based Vaccines | A/Wisconsin/588/2019 pdm09-like virus |
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What Is The Best Way To Locate A Flu Vaccine Clinic
People can obtain flu shots through a health care professional’s office, at community health departments, and at many pharmacies. Additionally, many employers and schools host flu shot clinics. Some employers may offer the vaccine free of charge. A health care professional’s office should be able to provide information about flu shot clinics available in the community.
Bc Doctors Warn Of Nasty Flu Season Tout Vaccines To Ward Off Twindemic
Doctors in British Columbia are warning that the province could see a nasty flu season this year after the influenza virus all but vanished last season.
Dr. Brian Conway, medical director of the Vancouver Infectious Diseases Centre, said he’s watching this year carefully for a number of reasons.
The biggest factor, he said, is the difference between current, relaxed COVID-19 protocols and the COVID-19 restrictions that were in place last winter, such as bans on social gatherings and travel restrictions.
Read more: Hardly any Canadians caught the flu last year. What can we expect this fall?
“Flu is transmitted in a way that’s similar to COVID, and since we had all of these public health measures in place to prevent COVID transmission, they were even more effective at preventing influenza transmission,” he said.
“It may put in people’s minds the idea that flu is gone since there was none last year and nothing could be further from the truth.”
Conway said he was also concerned that because there was no major flu season last year, people likely won’t have the same level of antibodies against influenzas that they would have developed if the virus was circulating.
The potential for people to contract both COVID and the flu at the same time — a situation doctors have little experience or evidence to respond with — is also a worry, he added.
Read more: How health measures aimed at COVID-19 routed the flu in Canada this season
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Why Should People Get Vaccinated Against Flu
Influenza is a potentially serious disease that can lead to hospitalization and sometimes even death. Every flu season is different, and flu can affect people differently, but millions of people get flu every year, hundreds of thousands of people are hospitalized and thousands to tens of thousands of people die from flu-related causes every year. Flu can mean a few days of feeling bad and missing work or it can result in more serious illness. Complications of flu can include bacterial pneumonia, ear infections, sinus infections and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes. An annual seasonal flu vaccine is the best way to help protect against flu. Vaccination has been shown to have many benefits including reducing the risk of flu illnesses, hospitalizations and even the risk of flu-related death in children. While some people who get a flu vaccine may still get sick, flu vaccination has been shown in several studies to reduce severity of illness.
Antigenic Shift And Pandemic Influenza
Antigenic shift is a dramatic change in the H antigen of influenza A. This occurs unpredictably and infrequently.98Antigenic shift gives rise to pandemic influenza subtypes by 1 of 2 ways:
- an avian or other animal virus directly adapts so that it can infect humans
- an avian or other animal virus mixes with a human virus, called genetic reassortment
There have been 4 influenza pandemics in the 20th and 21st centuries:
- 1918
- 1968
- 2009
Each of these pandemic strains replaced the previously circulating influenza A subtype and went on to circulate as seasonal influenza.
More recently, various avian influenza A virus subtypes have caused human infections. Examples are H5N1, H7N9 and H9N2. Sustained human-to-human transmission of these subtypes has not been reported.101,102
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Individuals With Symptoms Of Covid
During the COVID-19 pandemic, individuals should postpone influenza vaccination until they have recovered if they have:
- acute symptoms of COVID-19
- any symptoms of acute respiratory infection, including minor symptoms such as sore throat or runny nose
This is because they can pose an unnecessary risk to others and healthcare providers if they have COVID-19. Individuals with COVID-19 symptoms should visit a healthcare professional or contact their local public health authority for information on getting tested.
What Kinds Of Flu Vaccines Are Available
CDC recommends use of any licensed, age-appropriate influenza vaccine during the 2021-2022 influenza season. Available influenza vaccines include quadrivalent inactivated influenza vaccine , recombinant influenza vaccine , or live attenuated influenza vaccine . No preference is expressed for any influenza vaccine over another.
Quadrivalent flu vaccines include:
Are any of the available flu vaccines recommended over others?
For the 2021-2022 flu season, the Advisory Committee on Immunization Practices recommends annual influenza vaccination for everyone 6 months and older with any licensed, influenza vaccine that is appropriate for the recipients age and health status, including inactivated influenza vaccine , recombinant influenza vaccine , or live attenuated nasal spray influenza vaccine with no preference expressed for any one vaccine over another.
There are many vaccine options to choose from, but the most important thing is for all people 6 months and older to get a flu vaccine every year. If you have questions about which vaccine is best for you, talk to your doctor or other health care professional.
Who Should Vaccinate?
Everyone 6 months of age and older should get an influenza vaccine every season with rare exception. CDCs Advisory Committee on Immunization Practices has made this recommendation since the 2010-2011 influenza season.
More information is available at Who Needs a Flu Vaccine.
Who Should Not Be Vaccinated?
When should I get vaccinated?
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What Should I Do If I Have Had A Serious Reaction To Seasonal Flu Vaccine
Tell your doctor what happened, the date and time it happened, and when you got the flu shot.
Ask your doctor, nurse, or health department to file a Vaccine Adverse Event Reporting Systemexternal icon form, or call VAERS at 1-800-822-7967. Reports are welcome from all concerned individuals: patients, parents, health care providers, pharmacists and vaccine manufacturers.
Safety Of Influenza Vaccine During Pregnancy Or Breastfeeding

Influenza vaccine is safe to give during any stage of pregnancy or while breastfeeding for both the mother and her baby.86-89 Several systematic reviews have shown no association between influenza vaccination in pregnancy and adverse birth outomes.90,91
Standard influenza vaccines are currently preferred for use in pregnancy because a large body of evidence supports their safety in pregnant women. While the use of cell-based influenza vaccines in pregnancy has not been assessed, there are no theoretical concerns regarding their safety in pregnant women.
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All People Aged 6 Months
Registered for use in people aged 6 months.
Quadrivalent inactivated influenza vaccine
Each 0.5 mL monodose pre-filled syringe contains:
- 15 µg haemagglutinin of each of the 4 recommended influenza virus strains
- 0.05 µg ovalbumin
Registered for use in people aged 6 months.
Quadrivalent inactivated influenza vaccine
Each 0.5 mL monodose pre-filled syringe contains:
- 15 µg haemagglutinin of each of the 4 recommended influenza virus strains
- 100 µg formaldehyde
Registered for use in people aged 6 months.
Quadrivalent inactivated influenza vaccine
Each 0.5 mL monodose pre-filled syringe contains:
- 15 µg haemagglutinin of each of the 4 recommended influenza virus strains
Also contains traces of:
Registered for use in people aged 3 years.
Quadrivalent inactivated influenza vaccine
Each 0.5 mL monodose pre-filled syringe contains:
- 15 µg haemagglutinin of each of the 4 recommended influenza virus strains
- 100 ng ovalbumin
Registered for use in people aged 5 years.
Quadrivalent inactivated influenza vaccine
Each 0.5 mL monodose pre-filled syringe contains:
- 15 µg haemagglutinin of each of the 4 recommended influenza virus strains
- < 1 µg ovalbumin
Registered for use in people aged 9 years.
Quadrivalent inactivated influenza vaccine
Each 0.5 mL monodose pre-filled syringe contains:
- 15 µg haemagglutinin of each of the 4 recommended influenza virus strains
May contain traces of:
Registered for use in people aged 65 years.
Adjuvanted quadrivalent inactivated influenza vaccine
What Are The Possible Reactions After The Vaccine
LAIV contains weakened influenza viruses and may cause mild influenza symptoms but these are much milder than those due to influenza infection. Symptoms may include a runny or stuffy nose, cough, sore throat and fever. Other symptoms can include headache, decreased appetite, weakness, muscle soreness, chills, vomiting, stomach ache and irritability.
It is important to stay in the clinic for 15 minutes after getting any vaccine because there is an extremely rare possibility, less than 1 in a million, of a life-threatening allergic reaction called anaphylaxis. This may include hives, difficulty breathing, or swelling of the throat, tongue or lips. Should this reaction occur, your health care provider is prepared to treat it. Emergency treatment includes administration of epinephrine and transfer by ambulance to the nearest emergency department. If symptoms develop after you leave the clinic, call 9-1-1 or the local emergency number.
It is important to always report serious or unexpected reactions to your health care provider.
Guillain-Barré Syndrome is a rare condition that can result in weakness and paralysis of the bodys muscles. It most commonly occurs after infections. In rare cases, GBS can also occur after some vaccines. GBS may be associated with influenza vaccine in about 1 per million recipients.
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Adverse Events After Adjuvanted Influenza Vaccine
Clinical trials show a higher rate of injection site reactions in adults aged 65 years after receiving the adjuvanted influenza vaccine, compared with standard influenza vaccines.
Around 30% of people who received Fluad reported injection site reactions, compared with around 20% of people who received standard influenza vaccine. Both groups reported similar rates of systemic reactions.76 Overall, a similar proportion of people vaccinated with Fluad Quad experience injection site and systemic reactions as those vaccinated with Fluad.77
Rates of severe or serious adverse events do not increase after receiving the adjuvanted vaccine. This has been shown in clinical trials and post-licensure surveillance studies.76-79
Adjuvanted influenza vaccine is only registered for use in people aged 65 years. This vaccine is not recommended in younger people. However, clinical trials in some younger populations and post-licensure safety data after an adjuvanted vaccine was inadvertently given to younger people suggest a similar safety profile to that seen in people aged 65 years.80-82
Can You Get Covid
According to the CDC, “While it’s not possible to say with certainty what will happen in the fall and winter , CDC believes it’s likely that flu viruses and the virus that causes COVID-19 will both be spreading. In this context, getting a flu vaccine will be more important than ever.” There is no evidence to suggest that it is not possible to have both diseases at the same time.
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Can The Flu Shot Give Me The Flu
No. All flu vaccines used in Australia are inactivated, which means they do not contain the live flu virus so you can’t catch the flu from the vaccine.
Less than 1 in 6 people experience side effects from the flu shot that are similar to the early signs of the flu. These may include fever, tiredness and muscle aches. These side effects can start within a few hours of vaccination and sometimes last for 1 to 2 days. They usually go away on their own, once your body has developed an immune response to the vaccine, which will protect you from the flu virus.
Its important to remember that the side effects show the vaccine is triggering an immune response, which is what its designed to do.
People With Medical Conditions That Increase Their Risk Of Influenza
People aged 6 months with medical conditions specified in this List. Medical conditions associated with an increased risk of influenza disease and severe outcomes are strongly recommended to receive annual influenza vaccine.
People with these specific medical conditions have a higher risk of influenza or severe outcomes from influenza .9-29
People who have received a transplant
People who have had a haematopoietic stem cell transplant or solid organ transplant and are receiving influenza vaccine for the first time after transplant are recommended to receive:
- 2 doses at least 4 weeks apart the 1st time they receive influenza vaccine after the transplant
- 1 dose each year after that
Vaccine doses for people with the risk conditions in this list are funded under the NIP unless otherwise noted.
Conditions |
---|
Functional or anatomical asplenia, including:
|
Cardiac disease, including: |
|
Chronic neurological conditions, including: |
|
Long-term aspirin therapy in children aged 6 months to 10 years |
Chronic liver diseasea |
Obesity a |
Children born less than 37 weeks gestationa |
Harmful use of alcohola |
Pregnant women are strongly recommended to receive influenza vaccine in each pregnancy.
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Types Of Influenza Viruses
This is a picture of an influenza A virus. Influenza A viruses are classified by subtypes based on the properties of their hemagglutinin and neuraminidase surface proteins. There are 18 different HA subtypes and 11 different NA subtypes. Subtypes are named by combining the H and N numbers e.g., A, A. Click on the image to enlarge the picture.
There are four types of influenza viruses: A, B, C and D. Human influenza A and B viruses cause seasonal epidemics of disease almost every winter in the United States. Influenza A viruses are the only influenza viruses known to cause flu pandemics, i.e., global epidemics of flu disease. A pandemic can occur when a new and different influenza A virus emerges that both infects people and has the ability to spread efficiently among people. Influenza C virus infections generally cause mild illness and are not thought to cause human epidemics. Influenza D viruses primarily affect cattle and are not known to infect or cause illness in people.
Conversely, when two flu viruses are antigenically similar, a hosts immune response elicited by infection or vaccination with one of the viruses will recognize and neutralize the other virus, thereby protecting against the other virus.
Influenza A viruses also change both genetically and antigenically. Influenza A viruses have formed many separate, genetically different clades in recent years that continue to co-circulate.