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Vaccination Questions
Ask the Experts: Influenza Vaccinations

Released: November 01, 2022

Expiration: October 31, 2023

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Key Takeaways

  • Influenza vaccinations ideally should be provided in September or October but still should be pursued through the late winter or early spring for those who have not received vaccination.
  • Vaccination rates among all populations are insufficient, so taking advantage of any opportunity for vaccination is important.
  • In older adults, high-dose or adjuvanted influenza vaccine is recommended.
  • There are no data yet supporting the use of high-dose influenza vaccinations in immunocompromised adults younger than 65 years of age.

Timing of Influenza Vaccination
As long as there are no other mitigating factors, the ideal time to receive influenza vaccination would be in September or October to optimize effectiveness throughout the rest of the influenza season.

Earlier than September generally would not be recommended unless there is concern that later vaccination may not be possible. However, there are certain situations where one might consider providing influenza vaccination earlier or later. For instance, you might be concerned that the patient may not come back for their influenza vaccination; in these cases, being vaccinated a little earlier than recommended is better than not being vaccinated at all, particularly for a patient in a high‑risk population. 

Children who are getting school physicals in late summer can be considered for vaccination at this time because it represents a vaccination opportunity. Pregnant persons in the third trimester should be vaccinated to reduce the risk of influenza illness in their infants during the first months after birth.

In addition, children who are in their first influenza vaccination season and who require the 2‑dose series should receive vaccinations as soon as they are available to accommodate that multiple-dose schedule. If patients aren’t vaccinated by the end of October, there still is value in vaccinating as long as influenza viruses are circulating.

Our latest data from the 2020-2021 influenza season indicate that providing vaccinations still is challenging. For instance, fewer than 60% of children aged 6 months to 17 years were vaccinated for influenza. The lowest rate (50.8%) was in the oldest children—those 13-17 years of age. The highest rate (68.0%) was in the youngest group—those 6 months to 4 years of age. Among adults, the overall vaccination rate was 50.4%. The highest vaccination rate (75.2%) occurred in the oldest patients—those older than 65 years of age. The lowest rate (37.7%) occurred among the youngest adults—those 18-24 years of age. This is an area that clearly requires some improvement. 

Skin Reactions After Influenza Vaccinations
After influenza immunization, 24‑48 hours of redness and swelling is very common. This reaction may be to the influenza antigens or to some of the adjuvant or other components of the vaccine. It also may be a sign of innate immunity to the influenza virus.

With the COVID-19 vaccine, we occasionally saw a delayed memory immune reaction in the arm that might be severe for a few days. This is rare with influenza vaccine, but it has been described. It may be a vigorous response, and we sometimes even use steroids to treat it, but that may undermine the patient’s immune response. If this happens in a patient, they may be more hesitant to get immunized again. In such cases, one might suggest using a different vaccine formulation, if possible.

Vaccinations for Older Adults
There are often questions about the data supporting higher-dose vaccination for older adults. The New England Journal of Medicine published the results of a randomized, double-blind, active-controlled phase IIIb-IV trial comparing a trivalent inactivated influenza vaccine with 60 μg of hemagglutinin per strain (high dose) to one with 15 μg of hemagglutinin per strain (standard dose in adults 65 years of age or older). The investigators found a 24% reduction in protocol-defined influenzalike illness. In addition, antibody titers were higher in the high-dose group.

The current recommendation is that adults who are 65 years of age or older preferentially receive any one of the following higher-dose or adjuvanted influenza vaccines: quadrivalent high-dose inactivated influenza vaccine (HD-IIV4), quadrivalent recombinant influenza vaccine (RIV4), or quadrivalent adjuvanted inactivated influenza vaccine (aIIV4). 

A second issue for older adults relates to the availability of cell-culture–based high‑dose vaccines for older patients. At this time, unfortunately, there is not a higher-dose product that is cell-culture based. If egg allergies are the concern, the recombinant vaccine (RIV4) has a higher dose of that hemagglutinin component and can be a non–egg-based option for older patients. Finally, it would be better to give the standard dose product than no vaccination at all.

High-Dose Vaccinations for Immunocompromised Adults
We are often asked about whether it might be preferable to give a high-dose vaccination for younger patients who are immunocompromised. Unfortunately, no studies support this, so it is uncertain whether there would be a benefit.

On the other hand, the high-dose product should be used in older patients who are immunocompromised. The only vaccine product that is specifically not recommended for immunocompromised populations is the live attenuated vaccine (LAIV4). So, otherwise, it is still appropriate to administer other high‑dose products if you have older immune‑compromised patients.

Your Thoughts?
What are your concerns regarding providing influenza vaccinations for your patients? Leave a comment and join the conversation.