Original Scientific Article
Impact of vaccination against influenza A (H1N1)pdm09 virus on key reproductive performance indicators in a subclinically infected sow herd
Piotr Cybulski * ,
Aleksandra Woźniak ,
Tomasz Stadejek

Mac Vet Rev 2026; 49 (1): i - viii

10.2478/macvetrev-2026-0010

Received: 23 April 2025

Received in revised form: 23 August 2025

Accepted: 03 September 2025

Available Online First: 16 February 2026

Published on: 15 March 2026

Correspondence: Piotr Cybulski, piotr.cybulski.dvm@gmail.com
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Abstract

Even though viral replication and typical clinical symptoms of the infection in pigs are exclusively limited to the upper and lower respiratory tract, there have been case reports demonstrating correlation of IAV with reproductive health issues in sows, probably related to the effect of cytokines. The trial was conducted in a subclinically infected high-performing 8,000-head sow herd immunised against the influenza A (H1N1)pdm09 virus using RESPIPORC FLUpan H1N1 (Ceva Santé Animale, Libourne, France). The aim of this longitudinal field investigation was to evaluate the alterations in key reproductive performance indicators (i.e. abortion rate, return to oestrus rate, farrowing rate, and number of piglets born alive, stillbirths, and born weak per litter) before and after implementation of the vaccine. A significant improvement in selected indicators was achieved. After implementation of the vaccination against the influenza A (H1N1)pdm09 virus, the mean abortion rate decreased significantly (p=0.0025) in site A, whereas it remained unaffected in Site B. The return to oestrus rate increased significantly (p=0.0091) in Site B only (2.23% to 2.97%). The mean number of piglets born alive increased significantly at both locations (p<0.0001), reaching 17.7 animals per litter in each. The mean number of weak piglets born per litter was not significantly affected. Analysis of the number of mummified and stillborn piglets revealed a significant reduction of these parameters at both locations. The mean farrowing rates were not significantly altered by the vaccination. The findings highlight the role of less obvious problems affecting porcine reproduction.

Keywords: sows, influenza A virus, vaccination, reproductive performance, field study

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Copyright

©2026 Cybulski P. This is an open-access article published under the terms of the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Conflict of Interest Statement

The authors declared that they have no financial or non-financial conflict of interest regarding authorship and publication of this article.

Citation Information

Macedonian Veterinary Review. Volume 49, Issue 1, Pages i-viii, e-ISSN 1857-7415, p-ISSN 1409-7621, DOI:  https://doi.org/10.2478/macvetrev-2026-0010

The all content of the Macedonian Veterinary Review, except where otherwise noted, is licensed under a Creative Commons Attribution License.