Editor — Equine influenza vaccination is something that occupies a significant amount of our time and is deserving of more of our attention. It was therefore useful to publish this article (Rendle et al, 2019) outlining some relevant information and opinions. However, I was very surprised that the authors expressed a view of the relative likelihoods of adverse reactions to the different vaccine brands (Table 2) in the absence of any supportive evidence.
Readers and authors may be interested to know information from the Veterinary Medicines Directorate detailing numbers of reports of suspected adverse events following use of equine vaccinations. From January 2017 until June 2019 there were 132 suspected reactions to Proteq flu and Proteq flu-Te combined, and 194 suspected reactions to Equilis Prequenza and Equilis Prequenza Te combined. Data for just the first half of 2019, when many of us will have been vaccinating increased numbers of horses, indicate 39 Proteq flu/flu Te suspected reactions and 68 Prequenza/Prequenza Te suspected reactions. Clearly these data must be interpreted carefully as this is based on only those cases reported to the VMD and/or the vaccine manufacturer, and also market share will influence likelihood of reactions occurring; however, it does not appear supportive of an increased incidence of reactions to canarypox vectored vaccines as suggested in the article.
Yours faithfully,
Professor Andy Durham