Optimal Timing of Influenza Vaccination in Young Children: Practical Implications for Pharmacists

Influenza is still one of the most significant infectious diseases that threaten children, with those aged 2-5 years showing particular vulnerability to both infection and complications such as pneumonia, otitis media, and hospitalization.

Pharmacists, who are increasingly becoming a key part of the vaccination program in the community as well as in the health system, hold an important position in making sure that children get the influenza vaccine on time to protect them from the virus. Although vaccination of all eligible children has been and still is the main public health recommendation starting early fall, the latest evidence gives an indication that the timing of vaccination may impact clinical outcomes.

A cohort study newly published in The BMJ provides important insights into when children should ideally receive the flu vaccine and how pharmacists can apply these findings in practice.¹

Worsham and colleagues' study examined claims data spanning over 819,000 commercially insured children aged 2 to 5 years who received flu vaccines between 2011 and 2018.¹ The researchers leveraged the birth month natural "experiment," since a large number of preventive care visits are scheduled around birthdays.

They discovered that kids born in October were much more likely to get vaccinated in October and thus had the lowest rates of lab-confirmed flu compared with those born in any other month. For example, children born in October were about 12% less likely to be diagnosed with influenza than those born in August.

The research results imply that getting vaccinated in October, rather than at an earlier time, may be the best way to have protection during the influenza peak months.¹

Pharmacists can use this information to plan vaccine schedules, provide educational material to patients, and participate in community outreach. For the most part, pharmacies initiate their flu vaccine campaigns in August or even earlier, which is largely driven by the logistics of the supply and the early demand.

However, a child who is vaccinated too early may lose the immunity before the flu season reaches its peak, which is most likely between December and February in the US.²

While vaccination should not be delayed to the point of missing protection, pharmacists may consider advising parents to have their children vaccinated in October or November, as that would be a good compromise between early protection and immunity lasting throughout the entire flu season.

Pharmacists are also well-positioned to leverage natural reminders such as birthdays. Since many families schedule well-child visits and pharmacy visits around birthdays, aligning vaccination promotion with these milestones may improve uptake. A timely vaccine reminder for the caregivers of children who have birthdays in the fall could be the right step to a vaccination period that would bring lasting protection.

On the other hand, the pharmacy teams can also work with the doctors to avoid the duplication of services and, at the same time, make sure that children who are not visiting a provider have accessible immunization through community pharmacies.

Education of caregivers remains another essential pharmacist responsibility. Many parents believe that “the earlier the better” applies to flu vaccination. Pharmacists should emphasize that although early vaccination is better than no vaccination, receiving the vaccine closer to October may offer more durable protection for children, particularly if influenza activity peaks later in the season.³ Pharmacists can also counsel on the importance of annual vaccination, regardless of prior infection or vaccination history, since circulating strains and vaccine formulations change each year.

Ultimately, the BMJ research highlights that the time at which the flu vaccine is given can have a significant impact on clinical outcomes in young children. For pharmacists, the key takeaway is that they should be promoting vaccinations in these 2 months, as it would be more convenient for them to plan their campaigns and reminders around birthdays or other seasonal events and also be able to give parents accurate, scientific information about the right time to vaccinate and for how long the protection will last.

Although vaccination is still the first and foremost way to protect all children, pharmacists can still take a practical step of timing the vaccination so as to bring about maximum public health benefit and decrease the influenza load in the pediatric population.

REFERENCES

1. Worsham C M, Bray C F, Jena A B. Optimal timing of influenza vaccination in young children: population based cohort study BMJ 2024; 384 :e077076 doi:10.1136/bmj-2023-077076

2. Grohskopf LA, Ferdinands JM, Blanton LH, Broder KR, Loehr J. Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2024–25 Influenza Season. doi:10.15585/mmwr.rr7305a1.

3. Ferdinands JM, Gaglani M, Martin ET, et al. Waning Vaccine Effectiveness Against Influenza-Associated Hospitalizations Among Adults, 2015-2016 to 2018-2019, United States Hospitalized Adult Influenza Vaccine Effectiveness Network. Clin Infect Dis. 2021;73(4):726-729. doi:10.1093/cid/ciab045