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Wide World of Vaccines

October 2022

Fierce Flu Season Ahead?

Data From Australia Indicates US Flu Season Could Be Severe This Year


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Column Author: Maria Martinez, RN, BSN, MSN, MBA, CPN | Immunization Program Coordinator, Patient Care Services

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Column Editor: Angela Myers, MD, MPH | Director, Division of Infectious Diseases | Professor of Pediatrics, UMKC School of Medicine | Medical Editor, The Link Newsletter


Could the flu be coming back full force? While we saw a low number of flu cases last year, some experts are predicting that this year may be different in the Northern Hemisphere. We closely monitor what is occurring in the Southern Hemisphere from May through September, as flu season there can help predict what we might expect in the Northern Hemisphere.  

While the Southern Hemisphere is now on the tail end of its flu season, some of the data thus far may be cause for concern. Flu season in Australia started in April instead of June and has been the worst they’ve experienced in five years.1 As one of the earliest starts to the flu season on record in Australia, it may indicate a low level of immunity in the population.2

Over the past two years, many parts of the Northern Hemisphere have experienced mild flu seasons and low flu vaccination rates due to infection prevention measures related to COVID-19. However, many in the medical community have significant concern that we may be about to experience a fierce flu season. Most of the population was not exposed to the flu virus and therefore didn’t build natural immunity. Even more concerning to pediatric providers is data from Australia that children ages 5 to 9 had the highest rate of flu cases, followed by kids under 4 and teenagers. High rates of influenza in younger populations indicate that the overall population is less protected against the virus than in previous years.2

As we prepare for the upcoming flu season, it is vital to inform our patients that it may be a very strong flu season and to emphasize the importance of getting vaccinated. While viruses constantly mutate, the World Health Organization closely tracks the strains detected and helps guide vaccine development. The majority of influenza strains detected in the Southern Hemisphere were influenza A viruses, with Influenza A (H3N2) being predominant. The 2022-2023 flu vaccine is a quadrivalent vaccine targeting influenza A (H3N2), influenza A (H1N1), influenza B (B/Victoria lineage) and influenza B (B/Yamagata lineage).3

Incidence of influenza is just beginning to increase as we head into the flu season in the U.S. Influenza A is by far the dominant strain so far, and as seen in Australia, during October children 0-4 are showing the highest rates of respiratory illness. While the Midwest has yet to see a high number of influenza cases, areas of the southern and eastern U.S. are already at moderate to high levels.4

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Illustrations courtesy of CDC Fluview website4

Only time will tell what this respiratory season will bring to the Northern Hemisphere. The best thing we can do is continuing advocating for the importance of vaccination and educating our patients and families on the science behind it.



  1. Flu is surging in the Southern Hemisphere: is the US next? Advisory Board. Published July 27, 2022. Accessed October 14, 2022.
  2. Rodriguez A. Flu may be coming back with a vengeance, experts say, and children could be at risk. USA Today. Updated August 10, 2022. Accessed October 14, 2022.
  3. Merced-Morales A, Daly P, Abd Elal AI, et al. Influenza activity and composition of the 2022–23 influenza vaccine – United States, 2021-22 season. MMWR Morb Mortal Wkly Rep. 2022;71(29):913-919. Published July 22, 2022. Accessed October 14, 2022.
  4. Weekly U.S. influenza surveillance report. Centers for Disease Control and Prevention. Updated October 14, 2022. Accessed October 14, 2022.