Childhood influenza deaths in the USA

According to a report from CDC’s National Centre for Immunisation and Respiratory Diseases, 280 children died from influenza over a 12-month period to September 13, 2025.

This report covers the 24/25 winter season in the United States. This is the highest number of paediatric deaths since the disease became notifiable in 2004 (excluding the H1N1 swine flu outbreak in 2009/10).

Eighty nine percent were not fully vaccinated.

Sixty-one percent of deaths were in children under 9 years with the highest rate in infants under 6 months (11.1 per million). Influenza A was responsible for 86% deaths. A medical condition was identified in more than 50% cases.

Complications of influenza included sepsis, pneumonia and encephalopathy.

A serious influenza-associated medical complication.

Influenza-associated encephalopathy (IAE) was identified in 109 children with a median age of 5 years. Over fifty percent required mechanical ventilation and 21 died. Fifty five percent of the affected children were reported as previously healthy. Children who survive influenza associated encephalopathy often have neurological impairment.

A particularly severe form of encephalopathy (acute necrotising encephalopathy) resulted in 37 cases and 15 deaths.

Vaccination rates for influenza were low in both the encephalopathy group (16%) and those with the more severe form of the disease (13%). Annual influenza vaccination is recommended for all children older than 6 months.

More than 360,000 cases of laboratory confirmed influenza have been notified in Australia in the last 12 months (to 31 August 2025). This period covers our flu season and is more than double the previous 5-year average. This pattern is similar to many other countries in the post COVID-19 pandemic period.

The United States CDC report emphasizes the importance of influenza vaccine. It also makes reference to those children with underlying medical conditions who might be more at more risk of severe disease.

Children who are passing through crowded airports, travelling on public transports and visiting popular overseas events are certainly at higher risk of exposure. They might also have underlying health conditions.

What is the flu vaccine?

Only quadrivalent influenza vaccines were available in Australia for the 2025 season. There are 2 types, egg-based and cell-based. Each has 2 strains of Influenza A (H1N1, H3N2) and 2 strains of B in the vaccine.

Both types of vaccine are available under the National Immunisation Program (NIP). The NIP provides free influenza vaccines to those at most risk of serious disease.

A stronger flu vaccine is available to those 65 years and older. Older individuals may not be as responsive to vaccines as younger people. This is called immune senescence. It is also why diseases like influenza and COVID-19 are more likely to cause serious illness in this age group.

The over 65 years flu vaccine has more of the antigen than the standard vaccines. This should provide a better stimulus for antibody production. The composition is still the same.

Corporate flu programs need to be aware of the difference and make sure the older worker is given the appropriate vaccine.

Influenza vaccines can be administered at the same time as any COVID-19 vaccines.

The flu vaccine is not protective against avian influenza.

Who should receive the flu vaccine?

Everyone, 6 months and over is recommended to get a flu vaccine each year but only 30-35% people are vaccinated. Coverage is much greater in those over 65 years than in the younger age groups.

It is strongly recommended for certain groups to be vaccinated. These groups who will receive it free under the NIP (National Immunisation Program).

How effective are flu vaccines?

The effectiveness varies from year to year. It really depends on how close in structure is the vaccine to the circulating strains. Sometimes it is very close and at other times not so good. It is generally accepted that the effectiveness ranges from 40%-60%. The vaccines work better against the B strains of the virus and the H1N1 of the A strain but not so well for the H3N2 strain. It then depends on the predominant strain for the season to determine whether the vaccine was effective for the season.

A study of the 2019-2020 season (pre-pandemic) in the USA showed that vaccination prevented 7 million influenza-related illness, 3 million clinic visits, 100,000 hospitalisations and 7,000 deaths.

According to CDC, the southern hemisphere 2025 vaccine has reduced influenza-associated outpatient visits by 50.4% and hospitalisation by 49.7%.

Influenza vaccine and travel.

People often confuse a common cold with flu. “Colds” are due to several viruses which have a similar clinical picture. Colds are common, hence the name “common cold”. They are generally annoying rather than disabling.

Fortunately, influenza isn’t common, but it can be very unpleasant. A bout of influenza can last for several days. The symptoms can include fever, chills, dry cough, headaches, and severe fatigue. It is also highly contagious.

If you are a member of travelling group, you might be the index case for the group and the start of a holiday from hell. It might also be a particularly important holiday, a honeymoon, a family reunion or a wedding anniversary. It might also be an important business trip where decisions may be critical.

It is always important to consider the flu vaccine if there is something you would prefer not to miss!

The flu vaccine is the first vaccine you should consider in the context of travel. Influenza is the commonest health issue which can be prevented by vaccination.

Flu vaccination should never be considered in an age-based context when travelling. It is true that a person aged 20-40 years is less likely to experience serious illness, hospitalisation, or death - but they also have something to miss!