Influenza Vaccination: A Summary for Clinicians
Who Should Get Vaccinated?
Everyone who is at least 6 months of age should get a flu vaccine this season. The recommendation is intended to remove barriers to flu immunization, such as the need to determine whether each person has a specific indication for vaccination, and protect as many people as possible against the dangers of flu. The decision is supported by evidence that influenza vaccination is a safe preventive health measure with potential benefit across all age groups.
It’s especially important that certain people get vaccinated either because they are at high risk of having serious flu-related complications or because they live with or care for people at high risk for developing flu-related complications.
- Children aged 6 months--4 years (59 months);
- People 50 years and older;
- People with chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus);
- People who are immunosuppressed (including immunosuppression caused by medications or by human immunodeficiency virus);
- Women who are or will be pregnant during the influenza season;
- Children aged 6 months to 18 years receiving long-term aspirin therapy and who therefore might be at risk for experiencing Reye syndrome after influenza virus infection;
- Residents of nursing homes and other chronic-care facilities;
- American Indians/Alaska Natives;
- People who are morbidly obese (body-mass index is 40 or greater);
- Health-care personnel;
- Household contacts and caregivers of children aged younger than 5 years and adults aged 50 years and older, with particular emphasis on vaccinating contacts of children aged younger than 6 months; and
- Household contacts and caregivers of persons with medical conditions that put them at higher risk for severe complications from influenza.
When should vaccination occur?
Doctors and nurses are encouraged to begin vaccinating their patients as soon as flu vaccine is available in their area, and continue vaccinating through the remainder of the flu season or until all vaccine has been distributed. While influenza outbreaks can happen as early as October, most of the time influenza activity peaks in February.
When should health care providers start and stop vaccination efforts?
Vaccination should begin as soon as flu vaccine is delivered. Manufacturers distribute vaccine as production is completed. Distribution of vaccine can begin in August and continue through the fall. Most seasons, vaccine distribution is completed by December or January. Flu vaccines should be offered to people when they are seen by health care providers for routine care or as a result of hospitalization.
However, people and institutions planning large organized vaccination campaigns (e.g., health departments, occupational health clinics, and community vaccinators) should consider scheduling these events after at least mid-October, because the availability of vaccine in any location cannot be ensured consistently in early fall. Scheduling campaigns after mid-October will minimize the need for cancellations because of possible supply issues. These vaccination clinics should be scheduled through December, and later if feasible, with attention to settings that serve children, pregnant women, other people younger than 50 years of age at increased risk for influenza-related complications, people aged 50 years and older, health care personnel, and people who are household contacts of children aged younger than 60 months (5 years) or other people at high risk.
In addition, vaccination efforts should be structured to ensure the vaccination of as many people as possible over the course of several months, with emphasis on vaccinating before influenza activity in the community begins. Flu seasons vary in terms of length and severity. As a result, instead of setting a firm date to stop vaccinating, CDC generally recommends that vaccination efforts continue as long as influenza is circulating in the community. Clinicians should be aware that more than one wave of influenza can occur in communities, and that a decline in influenza illnesses during the fall or winter might be followed by another increase in illness caused by a different influenza virus strain. Clinicians deciding whether to continue vaccination efforts into Spring might consider accessing state and/or local influenza surveillance information to determine if flu is still circulating in the community.
However, end-of-season vaccination (in April and May) may particularly benefit the following people:
- Persons likely to be traveling to the Southern Hemisphere, where influenza may be circulating, and
- Children younger than 9 years of age being vaccinated against influenza for the first time who still have not gotten their second recommended dose of vaccine.
Vaccination for Children
Influenza vaccination is recommended for all children aged 6 months up to their 19th birthday.
Some children 6 months through 8 years of age require 2 doses of influenza vaccine. Children in this age group who are getting vaccinated for the first time will need two doses. Some children who have received influenza vaccine previously will also need two doses. The 2012 ACIP recommendations has an algorithm to help guide clinician decision-making regarding vaccination of children 6 months- 8 years of age.
The 2009 H1N1 virus continues to circulate. It wasn’t added to the seasonal vaccine until the 2010-2011 flu season. This means that children who did not get the 2009 H1N1 vaccine in 2009-2010, or a seasonal flu vaccine in 2010-2011 or later, will not be fully protected from the 2009 H1N1 virus until they receive 2 doses of the 2012-2013 flu vaccine.
2 Dose Vaccination Instructions
The first dose should be given as soon as vaccine becomes available, and the second dose should be given 28 more days after the first dose. The first dose “primes” the immune system; the second dose provides immune protection. Children who only get one dose but need two doses can have reduced or no protection from a single dose of flu vaccine. Two doses are necessary to protect these children. If your patient needs the two doses, begin the process early, so that children are protected before influenza starts circulating in your community. Make sure to remind the parent to follow up to get the child a second dose if they need one. It usually takes about two weeks after the second dose for protection to begin.
Children and adolescents at higher risk for influenza complications should continue to be a focus of vaccination efforts as providers and programs transition to routinely vaccinating all children and adolescents. Children under 6 months old are the pediatric group at highest risk of influenza complications, but they are too young to get an influenza vaccine. The best way to protect young children is to make sure members of their household and their caregivers are vaccinated.
The ACIP recommends that the TIV “Afluria” not be given to children younger than 9 years old, although it is approved for children aged 5 years and older.)
Vaccination for Adults
Everyone 6 months of age and older are recommended to get the flu vaccine, which includes even the healthiest adults. Vaccination is especially important for people at higher risk of serious influenza complications or people who live with or care for people at higher risk for serious complications.
Persons working in health care settings also should be vaccinated annually against influenza. Vaccination of health care professionals has been associated with reduced work absenteeism and with fewer deaths among nursing home patients.
People who should NOT be vaccinated include:
- People who have a severe allergy to chicken eggs (See below for information about less severe egg allergies.),
- People who have had a severe reaction to an influenza vaccination,
- Children younger than 6 months of age (influenza vaccine is not approved for children in this age group),
- People who are moderately or severely ill with or without fever should usually wait until they recover before getting flu vaccine. If you are ill, talk to your doctor about whether to reschedule the vaccination. People with a mild illness can usually get the vaccine.
- A history of Guillain-Barré Syndrome (GBS) within 6 weeks following receipt of influenza vaccine is a precaution for the use of influenza vaccine. Such individuals have a risk of recurrence of GBS with subsequent vaccination, and if not at high risk of severe influenza complications should generally not be vaccinated. However, while data are limited, the established benefits of influenza vaccination might outweigh the risks for many people who have a history of GBS and who also are at high risk for severe complications from influenza.
Vaccination of People with Egg Allergy
For the 2012-2013 season, there is a more permissive influenza vaccination recommendation for persons with egg allergies. Based on a thorough review of several recent studies, administration of both full doses and split doses of TIV have been tolerated by people with egg allergies, without serious reactions. The Advisory Committee on Immunization Practices (ACIP) recommends that for the 2012-2013 influenza season, people who have experienced only hives from consuming eggs can receive TIV intramuscularly as long as they are treated by a health care provider who is familiar with the potential manifestations of egg allergies and can be observed by a health care professional for at least 30 minutes after receiving each dose. The 2012 ACIP recommendations has an algorithm to help guide clinician decision-making regarding vaccination of people with egg allergy. Additional information about vaccinating people with egg allergy is available in the 2012 ACIP recommendations. LAIV should not be used in these patients.
Trivalent Inactivated Influenza Vaccine (TIV) Side Effects
- The viruses in the injectable influenza vaccine are inactivated so they do not cause influenza.
- Minor side effects that can occur include soreness, redness or swelling at the injection site, fever (low grade), or aches. If these problems occur, they begin soon after vaccination and usually last 1 or 2 days.
- Other rare side effects have been reported. More information about vaccine safety and side effects is available at Influenza Vaccine Safety.
Live, Attenuated Influenza Vaccine (LAIV) Side Effects
- LAIV is made from weakened viruses and does not cause influenza. The vaccine can cause mild illness in some people who get it.
- In children, minor side effects can include runny nose or mild temporary wheezing. Occasionally headache, vomiting, muscle aches, or fever have been reported.
- In adults, minor side effects can include runny nose, headache, sore throat, or cough.
- More information about vaccine safety and side effects is available at Influenza Vaccine Safety.