Influenza vaccines for pediatric use, 2021-2022

Update date: October 16, 2021

seasonal flu

The flu comes every year (at least, it has before the current pandemic). The flu season from the epidemiological point of view begins in week 40 of each year (this year, on Monday, October 4) and extends until week 20 of the following year.

Flu in the 2019-20 and 2020-21 seasons

In the 2019-20 season, the notification of flu cases stopped abruptly in mid-March 2020, when the end of the season was already approaching and coinciding with the outbreak of the SARS-CoV-2 pandemic. The global balance of the 2019-20 season shows that it passed in a similar way to the previous one (see the final report of the 2019-20 season carried out by the National Epidemiology Center / RENAVE).

Last flu season, 2020-21, was the first to coincide, all of it, with the current SARS-CoV-2 pandemic, and it was anomalous due to the drastic reduction in viral isolates and the detection of flu cases, despite the fact that the epidemiological surveillance systems remained active. This phenomenon has been global, and has occurred in a similar way in both hemispheres. In the month of December 2020, the Spanish Influenza Surveillance System (SVGE) showed the uncertainty with which the traditional increase in the incidence of the first weeks of January of each year was expected, until then. The reality is that the flu has barely appeared and so it continues. Other respiratory viruses also showed abnormal behavior, either due to the reduction in their incidence or, in some cases, their reappearance at unusual times of the year (the case of RSV in our environment). To date, the National Epidemiology Center has not published the final report for the 2020-21 season.

Epidemiological surveillance of influenza and forecasts for the current season

As the weekly report of the SVGE corresponding to week 35/2021 (9/Sep 2021) points out:

"In Europe, from week 40/20 to week 32/21, 963 of 1,043,991 non-sentinel samples were positive for influenza: 53% type A [11% A(H3), 13% A(H1)pdm09 and 76% ANS] and 47% type B. Only 14 of the type B viruses reported were lineage ascribed: 11 B/Victoria and 3 B/Yamagata In week 32/2021, 8,419 non-sentinel samples were analyzed, of which 4 have been positive ECDC points out that this season reported influenza activity has remained at a very low level, without exceeding the established epidemic threshold, probably due to the impact of the public health measures implemented to reduce the transmission of influenza. SARS-CoV-2 Influenza surveillance has improved as the 2020-21 season progressed and although there has been a slight decrease in the total number of tests analyzed, the percentage of positivity has decreased by more than 99% compared to previous seasons, with a weekly number of detections similar to the usual interseasonal ."

According to the same source, in the season that is about to start, 2021-22, a combined flu and covid surveillance system will be launched.

The flu season in the southern hemisphere is drawing to a close, and again, just like last season, the incidence of influenza has remained at record lows.

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Composition of influenza vaccines

In the month of February of each year, the WHO publishes its recommendations on the composition that flu vaccines should have in the northern hemisphere for the following season. The recommended composition for the 2021-22 season is shown in the attached image.

On this occasion, the degree of uncertainty regarding the prediction of the predominant viral strains is extraordinarily high, for the reasons explained by the WHO, related to the changes in the epidemiology of influenza experienced in the midst of the expansion phase of the pandemic and of extensive and intense protection measures against respiratory transmission (face masks, etc.) and restrictive social interaction and physical distance.

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Flu vaccines available in the 2021-22 season

Influenza vaccines for pediatric use are shown in the image above (table in JPG and PDF format). There are 5 inactivated vaccines (3 tetravalent ones grown in eggs and one in cell culture, plus a trivalent one grown in eggs). An attenuated, tetravalent, egg-cultured, intranasal vaccine will also be available this year. Note: see, at the end, the addendum informing of the limitations of the distribution of the intranasal vaccine.

For exclusive use in adults there will be 3 other vaccines (CIMA):

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Recommendations of the Ministry of Health on influenza vaccination 2021-22

On June 8, the Ministry of Health published its flu vaccination recommendations for the season that will begin next October. The population groups to be vaccinated are the same as in the previous season. The stated objectives are:

Consult other documents from the Ministry of Health on influenza vaccination.

Co-administration of flu and covid vaccines

[updated text] On October 4, 2021, the Ministry of Health published the "Guide on the use of vaccines for health personnel" in which the co-administration of covid vaccines with any other vaccine, including the flu vaccine, is allowed . Until that date, since there were no studies on the efficacy and safety of the co-administration of the covid vaccines with the other vaccines in use and due to the precautionary principle, a separation of one week had been recommended. Currently, some data is already available in the sense that vaccination against influenza and against covid, carried out simultaneously, are safe and preserve the immunogenicity of both (Lazarus R, SSRN, 2021, Wise J, BMJ, 2021) . Also in the updates of October 7, 2021 of the Comirnaty and Spikevax technical guidelines carried out by the Ministry of Health, the co-administration of these vaccines with any other is admitted, such as. that of the flu, pneumococcus, etc.

In this sense, add that the US CDC has already approved the co-administration of covid vaccines with other vaccines already in use, and the American Academy of Pediatrics (AAP) supports this measure in adolescents 12 years of age and older.

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Addendum, October 7, 2021. The company AstraZeneca has reported that the Fluenz Tetra vaccine will only be marketed as a presentation of 10 nasal applicators, containing 0.2 ml each, and the single-dose presentation is not available. The containers will be packaged in English, not in Spanish, a circumstance that has been authorized by the AEMPS (the technical sheet and the vaccine leaflet will be delivered in Spanish). Due to this exceptional circumstance, during the 2021-2022 season, the vaccine can only be purchased through the pharmacy services of the hospital network and pharmacy offices that act as clinic warehouses (guarantee pharmacies). As the single-dose presentation is not available this season, the vaccine cannot be purchased in community pharmacies.

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More information

Other references

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update history

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