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Influenza and other special groups


Individuals who are immune compromised are at high risk of severe influenza and complications. It is important to offer vaccination prior to the initiation of chemotherapy or immune suppressant medication. When this is not possible, influenza vaccination is recommended and can be given while an individual is receiving most treatments. Following cessation of chemotherapy, normal immune responses return after about 30 days. (1)  

Specialist’s advice should be sought when considering influenza vaccination of individuals who have received a haematopoietic stem cell or solid organ transplantation in the preceding 6 months. The response to influenza vaccination in those with a poorly functioning immune system is likely to be low, (2) additional preventative strategies are important to reduce their exposure to influenza. The vaccination is also recommended, although not funded, for those who are in close contact with individuals who are more vulnerable or at high risk of complications. Frontline healthcare workers are usually funded by their employer.

International travel

Studies have indicated that influenza is the most commonly contracted vaccine-preventable disease amongst international travellers. (3) Influenza outbreaks have been linked to travellers, (3-5) and certain types of travel where large numbers of people are likely to be in close proximity, such as cruise ship voyages (6-10) or events that include mass gatherings (11,12) are particularly high risk.  

A recent study observing travel-related influenza cases in an Australian paediatric hospital found that a high proportion of inter-seasonal influenza cases in children were linked to travel. (13) Out-of-season transmission of influenza-like illnesses, in conjunction with COVID-19 co-circulation, presents risks for severe disease in instances of co-infection,(14) particularly in the elderly and immunocompromised.

During the regular pre-travel consultation, all people travelling outside New Zealand should be advised to receive an influenza vaccination. The pre-travel consultation can also be used opportunistically to ensure that those who are eligible to receive funded influenza vaccine are vaccinated. This is particularly important for older travellers and those who are at higher risk of influenza complications.

In tropical countries, influenza activity can occur throughout the year, so vaccination is worthwhile regardless of season. In temperate climates in the Northern Hemisphere, influenza activity is more common from December to March. If a traveller has received the Southern Hemisphere vaccine in the preceding New Zealand autumn or winter and the same strains are circulating in the Northern Hemisphere, they should remain protected.  

If they have not been vaccinated in the proceeding autumn or winter or it is getting close to 6 months (15) since their last influenza vaccination, vaccination is recommended prior to travel. Note that any second vaccination is not funded# . Vaccination with the Southern Hemisphere vaccine at least two weeks prior to departure to any destination will offer some protection and would be preferable to having no vaccine.

If the Southern and Northern Hemisphere vaccine strains differ significantly, additional protection would be beneficial by having the local vaccine on arrival (stand-down period not required). Note that protection from the disease will not commence for at least a week after vaccination and therefore the traveller may be at risk of infection during that time. Vaccination with the Southern Hemisphere vaccine may offer some protection and would be preferable to having no vaccine. The Northern Hemisphere vaccine is not available in New Zealand.

# Except children aged under 9 years who are receiving influenza vaccine for the first time.

Southern Hemisphere vaccines vs Northern Hemisphere vaccines

Southern Hemisphere influenza vaccines
for 2023
Northern Hemisphere influenza vaccines for 2023–2024for egg-based vaccines)

WHO: All quadrivalent vaccines

  • A/Sydney/5/2021 (H1N1)pdm09-like virus
  • A/Darwin/9/2021 (H3N2)-like virus
  • B/Austria/1359417/2021-like virus
  • B/Phuket/3073/2013-like virus

WHO: Quadrivalent egg-based vaccines
(A virus strains are different for cell culture & recombinant vaccines)

  • A/Victoria/4897/2022 (H1N1) pdm09-like virus
  • A/Darwin/9/2021 (H3N2)-like virus
  • B/Austria/1359417/2021-like virus
  • B/Phuket/3073/2013-like virus

Are there any circumstances where people may consider re-vaccinating within a year?

Yes. By 6 months after vaccination, protective levels are lower and may not be sufficient to provide good protection. (15)

While the available vaccine gives some protection against influenza viruses circulating in the Northern Hemisphere, travellers (particularly older individuals and those who are at higher risk of influenza complications) who will be exposed, should consider vaccination or repeat vaccination prior to travel.

Please note that revaccination prior to travel is not funded.

Protective antibodies peak 1 week to 1 month after vaccination and then begin to wane. (16)

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