Influenza - disease issues Back to top

How serious a problem is influenza in the U.S.?

Influenza is the most frequent cause of death from a vaccine-preventable disease in the United States. From 1990 through 1999, an average of approximately 36,000 influenza-associated pulmonary and circulatory deaths occurred during each influenza season. In addition to fatalities, influenza is also responsible for more than 200,000 hospitalizations per year.

Where can I get information on influenza and its surveillance?

Information regarding influenza surveillance is available October through May from the CDC influenza website at www.cdc.gov/flu/weekly/fluactivity.htm In addition, periodic updates about influenza are published in the MMWR. State and local health departments should be consulted regarding availability of influenza vaccine, access to vaccination programs, information about state or local influenza activity, and for reporting influenza outbreaks and receiving advice regarding their control.

General information about influenza vaccination Back to top

For whom is influenza vaccine recommended?

ACIP recommends annual vaccination for all of the following:

• All persons age 6 months or older wanting to reduce the likelihood of becoming ill with influenza or of transmitting it to others • Adults age 50 years or older •   Children and teens age 6 months through 18 years •   All persons with any of the following conditions:     • a chronic disorder of the pulmonary or cardiovascular systems, including asthma •   a chronic metabolic disease (including diabetes), renal dysfunction, hemoglobinopathy, or immunosuppression (including immunosuppression caused by medications or by human immunodeficiency virus) •   a compromised ability to handle respiratory secretions or an increased risk for aspiration (e.g., cognitive dysfunction, spinal cord injury, or other neuromuscular disorder •   a child or adolescent (ages 6 months-18 years) who is receiving long-term aspirin therapy and, therefore, might beat risk for experiencing Reye syndrome after influenza infection •   Women who will be pregnant during the influenza season •   Residents of nursing homes or other chronic-care facilities that house persons of any age who have chronic medical conditions •   Likely to transmit influenza to persons at high risk, including     • healthcare workers, caregivers, or household members in contact with persons having high-risk conditions •   household contacts or out-of-home caretakers of children 0-59 months of age or of adults age 50 years or older.

Why should we target adults who are age 50 years and older, I thought it was suppose to be 65 years and older?

ACIP recommended lowering the age for routine influenza vaccination from age 65 years to 50 years beginning with the 2000-01 vaccination season in order to increase vaccination levels in the 50 to 64-year-old age group. From 24%–32% of persons in this age group have a chronic medical condition that places them at high risk for influenza-related hospitalization and death. Vaccination levels of high-risk persons aged 50–64 have been low and age-based strategies are usually more successful than risk-based vaccination strategies.

I've heard that a large percentage of people in the U.S. are already recommended for influenza vaccination. I don't understand why we don't just have universal influenza vaccination. It would be so much easier than assessing the risk of each patient.

It's true that the number of people who are in the age-based targets (i.e., age 6 months through 18 years, age 50 years or older) combined with those age 19-49 years with risk factors or who are household contacts of those with risk factors, amounts to 85% of the U.S. population. Though it may be a few more years before we reach universal influenza vaccination, ACIP now recommends vaccination for anyone who wants to reduce the likelihood of becoming ill with influenza or of transmitting it to others. Therefore, you can be comfortable recommending influenza vaccine for all your patients who want to be immune and don't want to spread influenza to others.

When should influenza vaccine be given?

You can begin offering vaccine as soon as vaccine becomes available. Early vaccination of children younger than age 9 years who are first time vaccinees (or who failed to get their second dose in the preceding season) can be helpful in assuring routine second doses before the influenza season begins. Planners of mass vaccination programs may want to consider scheduling their efforts after mid-October to increase the probability of having adequate vaccine supplies on hand.

We have noticed that CDC recommends that we begin vaccinating with seasonal influenza vaccine as early as September or even earlier. Does protection from seasonal influenza vaccine decline or wane within 3 or 4 months of vaccination? Should I wait until October or November to vaccinate my elderly or medically frail patients?

CDC recommends that seasonal influenza vaccine be administered to all age groups as soon as it becomes available. Antibody to seasonal inactivated influenza vaccine declines in the months following vaccination. However, antibody level at a point several months after vaccination does not necessarily correlate with clinical vaccine effectiveness. There are no studies that compare vaccine effectiveness according to the month when the vaccination was given. The authors of a recent review on antibody declines among the elderly after vaccination reported, “In conclusion, we found no compelling evidence for more rapid decline of the influenza vaccine-induced antibody response in the elderly, compared with young adults, or evidence that seroprotection is lost at 4 months if it has been initially achieved after immunization.” (See Skowronski, et al., Rapid Decline of Influenza Vaccine-Induced Antibody in the Elderly: Is it Real, or Is It Relevant? Journal of Infectious Diseases 2008;197:490-502). In addition, there is a lack of evidence for late-season outbreaks among vaccinated persons that can be attributed to waning immunity.

How late in the season can I vaccinate my patients with influenza vaccine?

Peak influenza activity does not generally occur until February. Providers are encouraged to continue vaccinating patients throughout the influenza season, including into the spring months (e.g., through May), as long as they have vaccine in the refrigerator and unvaccinated patients in their office. Because influenza occurs in many areas of the world during April through September, vaccine should be given to travelers who missed vaccination in the preceding fall and winter. Another late season use of vaccine is for children younger than age 9 years who were vaccinated for the first time in the current vaccination season but failed to get their second dose; this will save them from having to get 2 doses in the next vaccination season. For each of these situations, vaccine can be given through the month of June since injectable influenza vaccine customarily has a June 30 expiration date.

Which travelers are recommended to be vaccinated?

Healthcare providers should vaccinate any person who failed to get vaccinated in the previous vaccination season and who wants to reduce their risk of acquiring influenza during their upcoming travel, particularly if they are at high risk for influenza-related complications. This includes persons who are traveling to the tropics, traveling with organized tourist groups at any time of year, or traveling to the Southern Hemisphere during April-September.

We are always concerned that there won't be enough vaccine to vaccinate our patients in the fall. What can we do to be assured that we've done all that we possibly can to avoid this type of situation?

It is never too early to begin planning for the coming fall's influenza vaccination program. The most important thing you can do initially is to place your order for vaccine from your usual source. Some manufacturers often stop taking pre-orders in mid-May. Be sure to include vaccine for pediatric patients needing two doses and also for your facility's healthcare workers as part of your overall campaign.

Why do people who received influenza vaccine last year still need to get vaccinated this year when the viruses haven't changed?

Although the strains may sometimes be the same as in the previous year's vaccine, you should NOT use the previous season's vaccine you might still have in your refrigerator. Influenza vaccine distributed in the northern hemisphere expires on June 30 after each season; expired vaccine should NEVER be administered. Secondly, antibody titers that persons might have achieved from the previous year's vaccination will have waned and need to be boosted with a dose of the current year's vaccine.

If an unvaccinated patient who has just recovered from a diagnosed case of influenza comes into our clinic, should we vaccinate him?

Yes. Influenza vaccine commonly contains three influenza vaccine virus strains; two for A viruses and one for a B virus which are prepared based on circulating viruses from the previous influenza season. Infection from one virus type does not confer immunity to other types and it would not be unusual to have exposure to more than one type during a typical influenza season. By all means, vaccinate this person!

How long does immunity from influenza vaccine last?

Protection from influenza vaccine is thought to persist for a year or less because of waning antibody and because of changes in the circulating influenza virus from year to year.

Some of my patients refuse influenza vaccination because they insist they "got the flu" after receiving the injectable vaccine in the past. What can I tell them?

There are several reasons why this misconception persists: (1) Less than 1% of people who are vaccinated with the injectable vaccine develop flu-like symptoms, such as mild fever and muscle aches, after vaccination. These side effects are not the same as having influenza, but people confuse the symptoms. (2) Protective immunity doesn't develop until 1–2 weeks after vaccination. Some people who get vaccinated later in the season (December or later) may get influenza shortly afterward. These late vaccinees develop influenza because they were exposed to someone with the virus before they became immune. It is not the result of the vaccination. (3) To many people "the flu" is any illness with fever and cold symptoms. If they get any viral illness, they may blame it on the flu shot or think they got "the flu" despite being vaccinated. Influenza vaccine only protects against certain influenza viruses, not all viruses. (4) The influenza vaccine is not 100% effective, especially in older persons. The vaccine is effective in protecting 90% of healthy young adult vaccinees from illness when the vaccine strain is similar to the circulating strain. However, the vaccine is only 30%–40% effective in preventing illness among frail elderly persons (although among elderly persons, the vaccine is 50%–60% effective in preventing hospitalization and 80% effective in preventing death).

Is a Vaccine Information Statement (VIS) mandatory or is it only recommended when administering influenza vaccine?

As of January 1, 2006, the use of a VIS for influenza vaccine became mandatory under the National Vaccine Injury Compensation Program. Two VISs are published annually, one for LAIV and one for TIV. Each can be found at www.immunize.org/vis along with many translations.

Are there recommendations for the prevention of institutional outbreaks of influenza?

The most important factor in preventing outbreaks is annual vaccination of all occupants of the facility, and all persons in the facility who share the same air as the high-risk occupants. Groups that should be targeted include physicians, nurses, and other personnel in hospitals and outpatient settings who have contact with high-risk patients in all age groups, and providers of home care to high-risk persons (e.g., visiting nurses, volunteers).

What is the recommended interval for receiving influenza vaccine after an allergy injection?

Vaccines can be administered at any time before or after administration of an "allergy injection."

Influenza vaccination of children Back to top

Which children should receive influenza vaccine?

ACIP recommends annual influenza vaccination for all children age 6 months through 18 years as well as all other children with chronic heart or lung disease, chronic metabolic disease (such as diabetes), renal disease, immunosuppression from any cause, hemoglobinopathy, HIV infection, or on chronic aspirin therapy. All household contacts of children from birth through age 59 months should be vaccinated also. Children who are residents of chronic care facilities should also be vaccinated each fall.

Which influenza vaccines can we give to children?

Of the three vaccines currently licensed for children, Fluzone (sanofi pasteur) can be used in children as young as 6 months of age; Fluvirin (Novartis), for children beginning at age 4 years; and FluMist (MedImmune), beginning at age 2 years. Fluarix (GlaxoSmithKline), FluLaval (GSK), and Afluria (CSL Biotherapies) may only be given to persons age 18 years and older.

Children younger than age 9 years need 2 doses of influenza vaccine. Should 2 doses be given each year until the child turns 9?

No. Two doses should be administered to children younger than age 9 years (i.e., 6 months through 8 years) the FIRST time the vaccine is given. If the child fails to get the second dose during that season, he should be given two doses in the subsequent influenza vaccination season (i.e., the next chronological year). If he isn't vaccinated in the subsequent season, he should only get one dose per year from that point on.

When a child needs 2 doses of influenza vaccine, can I give 1 dose of each type (injectable and nasal spray)?

Yes. As long as a child is eligible to receive nasal spray vaccine (i.e., is in the proper age range and health status), it is acceptable to give 1 dose of each type of influenza vaccine. The doses should be spaced at least 4 weeks apart.

If a child receives influenza vaccine at age 34 or 35 months for the first time (0.25 mL dose) and then returns for the second dose at age 37 months, should we give another 0.25 mL dose or should we give the 0.5 mL dose that is indicated for ages 3 and older?

The child should always receive the dose appropriate for his or her age at the time of the clinic visit; at age 37 months that would be 0.5 mL.

Now that we are recommended to routinely vaccinate all pediatric patients ages 6 months through 18 years, it may be difficult to assure that first-time vaccinees younger than 9 years old receive two doses of influenza vaccine. Any suggestions?

The ACIP has suggested these patients may be given their first dose of vaccine as soon as vaccine becomes available.

A five-year-old child received her second MMR a week ago. How long should she wait before receiving live attenuated influenza vaccine (LAIV)?

LAIV can be administered simultaneously with another live vaccine (e.g., MMR, varicella), but if not given at the same time, ACIP recommends waiting four weeks before administering the second live vaccine.

Influenza vaccination of selected populations Back to top

Is influenza vaccine recommended for pregnant women?

Yes. ACIP recommends that because of the increased risk for influenza-related complications, women who will be pregnant during the influenza season should be vaccinated. Vaccination can occur in any trimester, including the first. Only inactivated (injectable or TIV) vaccine should be given to pregnant women.

Can thimerosal-containing vaccine be given to pregnant women?

Yes, unless you live in a state that has enacted legislation restricting use in pregnant women. There is no scientific evidence that thimerosal in vaccines, including influenza vaccines, is a cause of adverse events, unless the patient has a systemic allergy to thimerosal.

Do diabetics who control their disease with diet need influenza vaccine?

Persons with a metabolic disease, including diabetes, should receive annual influenza vaccination with the inactivated vaccine. All persons age 50 years or older should receive annual influenza vaccination regardless of the presence of chronic disease.

Should siblings of persons with a high-risk condition receive influenza vaccine even though the patient received the vaccine?

Yes. All household contacts (ages 6 months and older) of persons with "high-risk" conditions, including contacts of infants and young children from birth through age 59 months, and adults ages 50 years and older, should receive annual influenza vaccination.

Is influenza vaccine safe to administer to patients with multiple sclerosis?

Yes. Multiple sclerosis is not a contraindication to any vaccine, including influenza and pneumococcal vaccines. However, these patients should receive inactivated influenza vaccine and not the live, intranasal vaccine.

Does influenza vaccine increase the HIV titer in the blood of people with HIV infection?

Although some studies have demonstrated a transient increase in replication of HIV following inactivated influenza vaccine, other studies have not found this. This temporary increase in HIV titer has not been associated with deterioration in either T-lymphocyte counts or clinical condition. ACIP believes that annual influenza vaccination with inactivated vaccine will benefit many HIV-infected persons.

Influenza vaccination issues for healthcare workers Back to top

Which healthcare personnel should be vaccinated against influenza?

It is important to vaccinate ALL hospital and outpatient-care personnel that have direct contact with patients. In addition to physicians and nurses, vaccination in a hospital setting also includes full-time and part-time employees in radiology, laboratories, pharmacy, human resources, facilities management (housekeeping), food services, or laundry. Vaccinate volunteers as well. Others that should be vaccinated are emergency response workers, employees of nursing homes and assisted living programs, and providers of home care.

Which employees of chronic care facilities and nursing homes should be vaccinated against influenza?

All employees of long term care facilities who have any patient contact and do not have a valid contraindication should receive annual influenza vaccination.

What are the ACIP recommendations for influenza vaccination of healthcare personnel?

Because health care personnel (HCP) provide care to patients at high risk for complications of influenza, HCP should be considered a high-priority group for receiving vaccination. Achieving high rates of vaccination among HCP will protect staff and their patients, and reduce disease burden and healthcare costs. Vaccination rates of HCP are shamefully low; the 2004 National Health Interview Survey revealed only 42% had been vaccinated. On February 24, 2006, CDC devoted an entire MMWR Recommendations and Reports to influenza vaccination of HCP. These recommendations are summarized in the following points:

•   All HCP should be educated regarding the benefits of influenza vaccination. •   Influenza vaccine should be offered annually to all eligible HCP. •   Obtain a signed declination from HCP who decline influenza vaccination. • Monitor HCP influenza vaccination coverage and declination at regular intervals. •   Use the level of HCP vaccination coverage as one measure of a patient-safety quality program.

To obtain a copy of these CDC recommendations for healthcare personnel, go to www.cdc.gov/mmwr/preview/mmwrhtml/rr5502a1.htm?s_cid=rr5502a1-e

What is the Joint Commission's recommendation on vaccinating healthcare workers against influenza?

In January 2007, a new infection control standard of the Joint Commission became effective that requires accredited organizations to offer annual influenza vaccination to staff, volunteers, and licensed independent practitioners who have close patient contact.

What are the ACIP recommendations for use of the intranasal live attenuated influenza vaccine (LAIV) in healthcare personnel (HCP)?

ACIP recommends that HCP for whom LAIV is not contraindicated be allowed to receive it, with the exception of those who are in contact with patients who are severely immunosuppressed during periods when they require a protective environment (e.g., persons with bone marrow transplants who are hospitalized and in protective isolation). These HCP should receive trivalent inactivated influenza vaccine (TIV) instead. HCP who have close contact with persons having lesser degrees of immunosuppression (e.g., persons with diabetes, persons with asthma taking corticosteroids, or persons infected with HIV) are especially encouraged to receive LAIV if they themselves are healthy, not pregnant, and are younger than age 50 years. HCP use of LAIV might also increase availability of inactivated influenza vaccine for persons at high risk.

Why is influenza vaccination important for healthcare workers? We already encourage them to stay home from work when they are sick.

Unfortunately, by the time a healthcare worker has symptoms of influenza, they will have already exposed many patients since the virus is shed for 1-2 days before symptoms begin. Do the right thing. Starts planning early to make sure all employees in your work setting receive annual influenza vaccination before the influenza season begins.

I heard about a hospital where more than 95% of employees received influenza vaccine last year. How did they achieve such a high level of vaccination?

Virginia Mason Medical Center in Seattle, WA, completed 2 years of mandatory employee influenza vaccination, achieving 98% compliance in the 2006-07 year. Toolkits, as well as other materials from a variety of organizations and the presentation on the Virginia Mason program given at the 2007 National Influenza Vaccine Summit, are available to you at www.preventinfluenza.org/profs_workers.asp

We recommend our healthcare personnel receive LAIV, but question whether NICU staff can receive this vaccine without compromising our neonates.

Neonates in an NICU are not considered severely immunocompromised. NICU personnel may receive LAIV if otherwise eligible (younger than 50 years, healthy, and not pregnant).

Contraindications and precautions Back to top

For whom is influenza vaccine contraindicated?

Persons who have experienced a severe allergic reaction to a prior dose of influenza vaccine, or who are known to have a severe allergy to a vaccine component (such as egg protein) should not be vaccinated. Vaccination should be deferred for a person with moderate or severe acute illness until his/her condition improves. The use of live attenuated influenza vaccine (LAIV) is contraindicated in persons with a chronic disease that constitutes an increased risk when exposed to wild influenza virus (e.g., asthma, heart and renal disease, diabetes), pregnant women, immunosuppressed persons, children younger than age 2 years, and adults older than age 49 years. A history of Guillain-Barré syndrome occurring within 6 weeks of previous influenza vaccine is a precaution for TIV and LAIV.

Which patients with egg allergy should not receive influenza vaccine?

For those who claim egg allergy, determine the nature of the allergy. If it is severe (anaphylaxis, urticaria, bronchospasm), do not vaccinate. You might consider consultation with an allergist. Protocols for desensitization have been published. For allergies other than severe, give the vaccine. If a person can eat eggs in any form, they may receive influenza vaccine without prior testing.

We usually instruct our patients that they should separate vaccinations and allergy shots by at least 24 hours because if there were a reaction to one or the other, it wouldn’t be possible to determine which was the cause. This becomes problematic during influenza vaccination season. What should we do?

The probability of a serious allergic reaction following any vaccine is extremely low if the person is properly screened. ACIP has not issued a recommendation that desensitization injections and vaccines be separated by any specific time period; consequently, we feel that you should take the opportunity to vaccinate.

LAIV issues Back to top

For whom can the intranasal influenza vaccine be used?

The live attenuated influenza vaccine (LAIV), FluMist is currently approved for use only for healthy non-pregnant persons ages 2 through 49 years. Many of these persons are among the groups that are targeted for vaccination, including healthcare personnel (excluding those in close contact with severely immunosuppressed persons during periods when the immunocompromised person requires a protective environment) and other persons in close contact with high-risk groups, including household contacts of high-risk persons, contacts of children from birth through age 59 months, and contacts of adults age 50 years and older. In addition, any healthy, nonpregnant person between the ages 2 through 49 years who wants to reduce their risk of influenza or of transmitting it to others can by vaccinated with FluMist.

Can LAIV be administered to persons with minor acute illnesses, such as a mild upper respiratory infection (URI) with or without fever?

Yes, however, if clinical judgment suggests nasal congestion is present that might impede delivery of the vaccine to the nasopharyngeal mucosa, deferral of administration should be considered until the congestion resolves.

If someone receives live attenuated influenza vaccine, should they be cautioned to wait four weeks before becoming pregnant?

Live attenuated influenza vaccine (LAIV), is contraindicated in pregnancy. Neither the manufacturer nor ACIP has made a recommendation for the minimum interval between vaccination and pregnancy. Because the duration of replication is similar to that of MMR and varicella viruses, it seems reasonable to follow the general rule for other live virus vaccines and avoid pregnancy for four weeks.

Can a woman who is breastfeeding receive live attenuated influenza vaccine (LAIV)?

Yes. Breastfeeding is not a contraindication for routine vaccination of breastfeeding women, including LAIV.

Can LAIV be given to contacts of immunosuppressed patients?

Like other live vaccines, LAIV should not be administered to immunosuppressed persons. ACIP has stated a preference for using inactivated influenza vaccine for household members, healthcare personnel, and others who have close contact with severely immunosuppressed individuals (e.g., patients with hematopoietic stem cell transplants) during those periods in which the immunosuppressed person requires care in a protective environment because of the theoretical risk that the live attenuated vaccine virus could be transmitted to the severely immunosuppressed individual and cause disease. Healthcare personnel or other persons who have close contact with persons with lesser degrees of immunosuppression (e.g., persons with diabetes, persons with asthma taking corticosteroids, or persons infected with human immunodeficiency virus) who are otherwise eligible for LAIV may receive it. No special precautions need to be taken by the vaccinated person.

How long after someone is vaccinated with seasonal live attenuated influenza vaccine (LAIV) must they stay away from a severely immunosuppressed person (a person who is in protective [reverse] isolation)?

Persons vaccinated with LAIV should avoid contact with any person who is severely immunosuppressed for at least 7 days after receiving LAIV. There are no restrictions on being in contact with any other patients.

Is LAIV contraindicated for asthmatics?

Persons with asthma should not receive LAIV. Persons with asthma and other chronic respiratory conditions should receive inactivated influenza vaccine.

Administering influenza vaccine Back to top

At what ages can the various injectable influenza vaccines be administered?

The range of ages for the 4 injectable vaccines is 6 months and older for FluZone (sanofi pasteur), 4 years and older for Fluvirin (Novartis), and 18 years and older for Fluarix (GSK), FluLaval (GSK), and Afluria (CSL).

How is the intranasal vaccine (LAIV) administered?

The vaccine dose (0.2 mL) comes inside a special sprayer device. A plastic clip on the plunger divides the dose into two equal parts. The patient is seated in an upright position with head tilted back. Half of the contents of the sprayer (0.1 mL) is sprayed into each nostril.

Some injectable influenza vaccine comes with a 5/8" needle attached. I thought we were supposed to use a 1-1½" needle for this IM vaccine in adults.

You're right. For intramuscular injection ACIP generally recommends the use of at least a 1" needle in adults. Some experts feel that a shorter needle can be used in adults weighing less than 60 kg, but ONLY if administration is in the deltoid and ONLY if the skin is stretched tight and the needle is placed at a 90 degree angle to the skin.

Sometimes I am unable to get 10 doses of influenza vaccine out of a 5.0 mL (10-dose) vial. Do you have any suggestions?

Certain vaccine syringes have small hubs where a volume of the vaccine that is withdrawn from the vial collects and is not available to be injected. Syringes without a hub are available; their use results in less vaccine wastage.

Storage and handling (LAIV and TIV) Back to top

How should LAIV and TIV be stored?

Both the trivalent (injectable) influenza vaccine (TIV) and the live attenuated influenza vaccine (LAIV) should be refrigerated at temperatures between 35°F (2°C) and 46°F (8°C).

Reviewed on 10/09