What’s New with the Flu

Last year’s flu season was back to almost normal levels due to COVID restrictions easing up. For 2024 we are monitoring the flu patterns in the southern hemisphere before the influenza season begins again in the northern hemisphere. Here’s an update for clinicians from Elsevier’s Tony Prosser, PharmD, Senior Manager, Clinical Drug Information. 

Influenza Season 2023-2024

To mitigate the effects of an unpredictable flu season, the best strategy is to encourage vaccination for influenza. Here are resources about this year’s influenza vaccine: 

• U.S. FDA: Influenza Vaccine for the 2023-2024 Season

• 2023-2024 CDC Flu Vaccination Recommendations Summary

• Drug Monograph from Elsevier’s Drug Information: Influenza Virus Vaccine 

The composition of the flu vaccines for 2023-24 included one update compared to the prior season vaccines. The influenza A(H1N1)pdm09-like vaccine virus component was updated for both egg-based and cell- or recombinant-based flu vaccines. 

Recommendation changes for the 2023-2024 flu season involves giving flu vaccine to those with egg allergies. It is recommended that those with egg allergy receive influenza vaccination even though most flu vaccines contain a small amount of egg protein. In those with egg allergy, any influenza vaccine (egg-based or non-egg based) that is appropriate for a person's age and health status may be given. Additional safety measures beyond standard vaccine administration recommendations are no longer recommended for influenza vaccination in those with egg allergies. Previously, administration in an inpatient or outpatient medical setting was recommended for those with severe egg allergy (i.e., symptoms other than hives with egg exposure). 

Recommended Timing 

Timing of influenza vaccination remains the same for the 2023-24 flu season; ideally in September and October but no later than end of October for those needing one dose. Clinicians should continue recommending influenza vaccinations as long as influenza virus poses a threat, which can be as late as May or June.  Regarding July/August flu vaccination, the CDC does not generally recommend getting the flu vaccine during these months for most people, however, the CDC does offer some considerations for July/August vaccinations for specific groups of people: 

• Adults (especially 65 years or older): Avoid July/August vaccination unless it is not possible to vaccinate in September or October. 

• Pregnant patients, 1st or 2nd trimester: Avoid July/August vaccination unless it is not possible to vaccinate in September or October.  

• Pregnant patients, 3rd trimester: Consider July/August vaccination to ensure newborn has adequate protection from influenza after birth since they would be too young for vaccination. 

• Children requiring two doses of vaccine should receive the 1st dose as soon as vaccine is available (this could be in July/August) and the 2nd dose at least four weeks after the first dose. 

• Pediatric health care provider visit timing: July/August flu vaccination can be considered when medical visits are during these months and there might not be another opportunity to vaccinate them in September or October. 

Influenza, RSV, and COVID-19

The 2022-2023 respiratory virus season saw three viruses: influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 (COVID-19). Vaccines and treatments are available for all three of them. Clinicians should continue to encourage vaccination and to monitor for any uptick in cases in their community. 

Visit the Influenza Healthcare Hub 

Elsevier has created the Influenza Healthcare Hub to help healthcare professionals navigate flu season. On the Influenza Healthcare Hub, you’ll find guidelines for testing and treatment, and how the influenza vaccine should be used to protect vulnerable populations. For more information, visit Elsevier’s Influenza Healthcare Hub.