Rapid communication Open Access
Like 0


We estimated interim influenza A vaccine effectiveness (VE) following a late sharp rise in cases during an influenza A(H3N2)-dominated 2021/22 season, after lifting COVID-19 restrictions. In children aged 2–6 years offered a live attenuated influenza vaccine, adjusted VE was 62.7% (95% CI: 10.9–84.4) in hospitalised and 64.2% (95% CI: 50.5–74.1) in non-hospitalised children. In non-hospitalised patients aged 7–44 years, VE was 24.8% (95% CI: 12.8–35.2); VE was non-significant in remaining age groups and hospital/non-hospital settings.


Article metrics loading...

Loading full text...

Full text loading...



  1. Emborg HD, Carnahan A, Bragstad K, Trebbien R, Brytting M, Hungnes O, et al. Abrupt termination of the 2019/20 influenza season following preventive measures against COVID-19 in Denmark, Norway and Sweden. Euro Surveill. 2021;26(22).  https://doi.org/10.2807/1560-7917.ES.2021.26.22.2001160  PMID: 34085632 
  2. Grove Krause T, Jakobsen S, Haarh M, Mølbak K. The Danish vaccination register. Euro Surveill. 2012;17(17):2.  https://doi.org/10.2807/ese.17.17.20155-en  PMID: 22551494 
  3. Voldstedlund M, Haahr M, Emborg H-D, Bang H, Krause T. Real-time surveillance of laboratory confirmed influenza based on the Danish microbiology database (MiBa). Stud Health Technol Inform. 2013;192:978. PMID: 23920752 
  4. Lynge E, Sandegaard JL, Rebolj M. The Danish national patient register. Scand J Public Health. 2011;39(7) Suppl;30-3.  https://doi.org/10.1177/1403494811401482  PMID: 21775347 
  5. Chung JR, Kim SS, Kondor RJ, Smith C, Budd AP, Tartof SY, et al. Interim estimates of 2021-22 seasonal influenza vaccine effectiveness - United States, February 2022. MMWR Morb Mortal Wkly Rep. 2022;71(10):365-70.  https://doi.org/10.15585/mmwr.mm7110a1  PMID: 35271561 
  6. Kissling E, Nunes B, Robertson C, Valenciano M, Reuss A, Larrauri A, et al. I-MOVE multicentre case-control study 2010/11 to 2014/15: Is there within-season waning of influenza type/subtype vaccine effectiveness with increasing time since vaccination? Euro Surveill. 2016;21(16).  https://doi.org/10.2807/1560-7917.ES.2016.21.16.30201  PMID: 27124420 
  7. Subbarao K. Live attenuated cold-adapted influenza vaccines. Cold Spring Harb Perspect Med. 2021;11(9):a038653.  https://doi.org/10.1101/cshperspect.a038653  PMID: 32253347 

Data & Media loading...

Submit comment
Comment moderation successfully completed
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error