FREQUENTLY ASKED QUESTIONS
When should people be vaccinated?
The optimal time for high-risk groups is March to April, in advance of the peak period of influenza activity (usually between May and September each year), however outbreaks may commence before or after these months. The vaccine can be given even when influenza virus activity has been identified, as protective antibody levels develop from four days to two weeks after immunisation.
The vaccine is funded only until 30th June 2010 for eligible patients.
Who should be immunised?
Influenza continues to be a major threat to public health world wide because of its ability to spread rapidly through populations. Anyone over 6 months of age can be immunised against influenza. However the vaccine is funded only for those people who fall under the eligibility criteria outlined above and in 'Resources section'.
Can you get influenza from the vaccine?
No. The vaccine has been made from virus that has been concentrated, inactivated then broken apart. It cannot cause influenza, as the vaccine does not contain any live viruses. When vaccinated, the body responds to the vaccine by producing an immune response. This can include systemic symptoms such as fever, malaise and myalgia. Other respiratory viruses circulate during the winter months and influenza vaccines do not protect against these. Most of these viruses cause milder infections (e.g. the common cold) and do not pose the same threat to those at ’high-risk’. They should not be confused with influenza. Certain other infections may, on occasion, produce influenza-like symptoms and quite severe illness, leading to the statements that the vaccine is ineffective.
Do VAXIGRIP®, FLUVAX® and INFLUVAC® contain thiomersal?
No. VAXIGRIP®, FLUVAX® and INFLUVAC® are preservative free. None of the vaccines contain thiomersal.
Can influenza vaccine be given to pregnant women?
Maternal influenza immunisation has substantial benefits for both mothers and infants. The seasonal influenza vaccine is normally given in the 2nd and 3rd trimesters but should be offered to women who will be in the 1st trimester when influenza is circulating. (Safety of influenza vaccination during pregnancy. Am J Obstet Gyn. 2009;201(6):547-552) click here for article.
BMJ - Critical illness due to 2009A/H1N1 influenza in pregnant and postpartum women: population based cohort study - click here for article.
The ANZIC inlfuenza Investigators and Australasian Maternity Outcomes Surveillance System
Can influenza vaccine be given to a woman who is breast-feeding?
Yes. The vaccine may be given safely to a lactating women.
Why does a child need two doses if vaccinated for the first time?
Younger children have a better immune response after two doses for the first influenza vaccination. This may be because they are more likely to be immunologically naive to influenza.
VACCINE EFFECTIVENESS
How effective is the vaccine for healthy adults?
Influenza vaccination is approximately 80% effective in preventing infection with influenza A and B viruses in healthy adults under 65 years of age, when there is a good match between the vaccine and circulating influenza strains.
How effective is the vaccine for older adults?
Although older people may have a reduced immune response to influenza vaccine compared with younger adults, they still benefit from influenza vaccination. Older people are more likely to have an associated condition and are more likely to develop complications from influenza.
How long after vaccination does it take for antibodies to be produced?
It takes up to two weeks for the vaccine to give full protection.
How effective is immunisation against influenza strains not included in the vaccine?
Effectiveness is reduced by the degree of diffference between virus and vaccine strains. The influenza virus does keep changing and new vaccines are formulated for each northern and southern hemisphere season. There may be some cross protection against an influenza virus not in the vaccine.
How long does immunisation last?
Protection should last throughout the influenza season and re-immunisation within 12 months is not usually necessary, unless travelling to the northern hemisphere during its peak influenza season. Immunisation is ideally provided in autumn, one or two months before the influenza season starts, to ensure that peak protection occurs during the season itself.
What are the expected responses?
Influenza vaccine is well tolerated, however some people have side effects following vaccination. These can include systemic symptoms such as fever, malaise and myalgia, and can occur in around 1% of adults. These symptoms are also more likely in children who have not previously been exposed to the vaccine or virus. Local reactions, including redness and induration at the injection site, may persist for one to two days in 10–64% of recipients, but these effects are usually mild.
What are the possible adverse events?
More rare events include allergic reactions, such as urticaria, pruritus, erythematous rash and dyspnoea have been reported. Rarely vasculitius, arthritis and transient thrombocytopaenia occur. Neurological disorders such as encephalopathy, neuritis or neuropathy or Guillain-Barre syndrome have been reported.
TRAVEL
Are there circumstances where people may consider re-immunising within a year, e.g. prior to travel?
Yes. When the available vaccine gives protection against influenza viruses circulating in the northern hemisphere, travellers - particularly those in ‘high-risk’ groups - who will be exposed to a northern hemisphere influenza season should consider immunisation or re-immunisation prior to travel. Protective antibodies peak one to two months after vaccination and then begin to wane.
At six to eight months after vaccination, protective levels are lower and may not be sufficient to provide good protection. Re-immunisation should be considered where the benefits to the patient outweigh the risks.
What should we advise international travellers about influenza vaccination?
People travelling outside New Zealand, who are in’high-risk’ groups and who have not received vaccine during the previous autumn, should consider immunisation depending on the season and their destination. In tropical countries, influenza activity can occur throughout the year, while in temperate climates in the northern hemisphere activity is more common between the months of December and March. The United States Advisory Committee on Immunization Practices (ACIP) recommendations are similar and recommend that people at high risk of influenza complications should consider receiving influenza vaccine before travel if they plan to:
a) travel to the tropics;
b) travel with large organised tourist groups at any time of the year (e.g. cruise ships); or
c) travel to temperate climates within the northern hemisphere (e.g. UK) between November and March.
IMMUNO-COMPROMISED
When is the best time to vaccinate the severely immuno-compromised?
The optimum time is prior to the initiation of chemotherapy or radiation treatment. Following cessation of cancer chemotherapy, normal immune responses return after about 30 days. A medical specialist’s advice should be sought when considering the repeat influenza vaccination of a patient following bone marrow transplantation.
The protective effectiveness of influenza vaccination is likely to be low in this group of patients, thus additional preventative strategies are needed. Hospital acquired influenza is the most likely route of infection so 'ringfencing' of such patients by immunising family members and hospital staff should be considered.
Who should not receive the vaccine?
Patients with known anaphylactic hypersensitivity to egg protein should, in most cases, not receive influenza vaccine. The vaccine, although purified, is produced in hens’ eggs and may contain residual egg protein. A patient with a history of Guillain-Barré syndrome should not be vaccinated. In general, for cases of patients at high risk from complications of influenza, specialist advice should be sought to weigh the relative risks.
References:
Ministry of Health Immunisation Handbook, Chapter 13, Influenza.
Ministry of Health Immunisation Handbook, Chapter 1, General Considerations.
