Why Vaccinate Healthy 2- to 17-Year-Olds Against Influenza?

FRANCE — On February 2, 2023, the French National Authority for Health (HAS) recommended extending flu shots to children aged 2-17 years without comorbidities.

For the first time this year, French healthcare professionals, like their counterparts in the United Kingdom and Spain (see box), are therefore being invited to offer this vaccination to all children.

The reasons are many. This approach seeks to reduce severe forms of disease in this population. It also aims to limit the spread of the virus within the general population and ease the burden of flu on the country's hospital systems.

Following the expansion of these recommendations, the target population for flu vaccination went from 16 million to 28 million people (ie, 40% of the general population of France). But the manufacturers are not fazed, reassuring public health planners that there will be enough vaccines to go round this year.

Overall, according to European modeling duplicated by the HAS, based on a flu vaccine efficacy of between 50% and 80% and a pediatric vaccine coverage between 40% and 50%, the reduction in flu cases could range between 18% and 58%. The same method also predicts a reduction in hospital admissions for flu of 17% to 71% and a drop in deaths of 1% to 90%.

Individual Benefits

The expected benefits for children include protecting them against the effects of the disease, avoiding missed school days, and enabling them to continue with their everyday activities, said Catherine Weil-Olivier, MD, a pediatrician and former head of general pediatrics at the Paris hospital trust in Colombes. She spoke during a press conference organized by Viatris, the manufacturer of one of the vaccines.

According to a study conducted by Sentinelles, France's primary care clinical surveillance network, 25%–50% of flu-related doctor's office visits involve children under age 15 years, said Weil-Olivier. Additionally, 38% of admissions to emergency departments for flu symptoms involve children aged 2-14 years.

Finally, the data reported by the HAS show that children are overrepresented in visits to primary care facilities and emergency departments in terms of flu symptoms, relative to their representation in the French population.

According to the figures, 9% of children under age 2 years have seen their doctor for flu symptoms, though this group only represents 2% of the population. This number goes up to 19% in the 2-to-4-year age range, which only represents 5% of the general population.

It should be noted that during the 2022–23 season, according to figures from the country's emergency care surveillance system, Oscour, 7% of severe flu cases reported by intensive care services involved children aged 0-4 years, and 4% involved children aged 5-14. Furthermore, of the 121 deaths reported (unconsolidated data), 4 occurred in children under age 15 years.

Effective and Well Tolerated

Literature analysis shows that vaccinating children aged 2-17 years against the flu is effective and well tolerated, according to the HAS. Cochrane Review studies concluded that seasonal vaccination of healthy children against the flu to prevent infection is effective (vaccine efficacy of 78% for live attenuated vaccines, 64% for inactivated vaccines).

In terms of their safety profile, pharmacovigilance data for childhood flu vaccines available in France (including Fluarix Tetra, Vaxigrip Tetra, Influvac Tetra, Flucelvax, and Fluenz Tetra) present no specific concerns. "European and global data confirm the safety of these vaccines in children," according to health authorities.

"We have years of experience of using flu vaccines. In children, the vaccine is effective and well tolerated," said Weil-Olivier, even adding that "vaccine efficacy is always better in children than in adults."

Families and the Vulnerable

Children aged 2-17 are the disease reservoir for the flu. "The flu epidemic begins in children and is followed around a fortnight later by an epidemic in other age groups," explained Weil-Olivier.

Therefore, the expected benefits of vaccinating children include limiting the spread of the illness within families; in schools, workplaces, and community settings; and in the general population and the most vulnerable members of society.

With vaccine coverage of 10% in the pediatric population, the number of flu infections in older adults would be around 10%, reported the HAS.

Experts also hope that reducing the spread of the virus within the population through vaccination will ease the burden of flu on hospitals. "All of our systems are on their knees. And last year was particularly difficult with the triple epidemic of flu, respiratory syncytial virus, and COVID. I think that individual as well as public health benefits should be taken into consideration," said Weil-Olivier.

Which Vaccine and Schedule?

Although the HAS recommends the nasal flu spray Fluenz Tetra as the vaccine of choice, since "this simpler mode of administration (nasal spray) would be more readily accepted by children and their parents," it is not available in France because of ongoing pricing negotiations.

Other vaccines with marketing authorization in France for children have been put forward, including Fluarix Tetra, Vaxigrip Tetra, Influvac Tetra, Fluenz Tetra, Flucelvax.

In practice, for children aged 6 months to 9 years, vaccination consists of administering two doses as primary vaccines, followed by an annual booster, as is the case for adults.

"My suggestion is that we start vaccinating young children from October 17, as immunogenicity studies have shown that they are only really protected from the second dose," said Weil-Olivier.

From the age of 9 years, the vaccine schedule is one annual booster, as with the rest of the population.

Healthcare professionals authorized to administer this vaccination are doctors, pharmacists (the latter can vaccinate children aged 11 years and up), nurses, and midwives.

Many European Countries Already Recommend This Vaccination

In 2022, a total of 12 European countries were already recommending flu vaccination in healthy children: Austria, Spain, Estonia, Finland, Italy, Ireland, Latvia, Malta, Poland, United Kingdom, Slovakia, and Slovenia. Globally, Australia, Canada, the United States, and New Zealand have also adopted this strategy. Most countries start vaccinating from the age of 6 months.

This article was translated from the Medscape French Edition.

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