Reassuring findings about vaccine administration

New research suggests that vaccines against equine influenza virus (EIV) and equine herpesvirus types 1 and 4 (EHV-1/4) can safely be given on the same day.


New research from Ireland suggests that vaccines against equine influenza virus (EIV) and equine herpesvirus types 1 and 4 (EHV-1/4) can be given to a horse on the same day without compromising his immune response.

To investigate the possibility of potential immunological interference between these two commonly administered vaccines, researchers at the Irish Equine Centre in Kildare divided 30 healthy horses into two groups. The first received the EIV vaccine and a combination EHV-1/4 vaccine two weeks apart. The second group was given those vaccinations on the same day. In addition, blood samples were taken from each horse before and after vaccination to measure levels of antibodies against both influenza and equine herpesvirus 1 and 4.

The data showed that the horses vaccinated on the same day had a slightly higher antibody response to the EIV vaccines than did the horses vaccinated two weeks apart and that there was no significant difference in EHV-1/4 antibody response between the groups.

The researchers conclude that administering selected vaccines against EIV and EHV-1/4 concurrently will not compromise the response of the immune system.

Reference: “Concurrent vaccination against equine influenza and equine herpes virus—a practical approach,” Influenza and Other Respiratory Viruses, published online May 2016

This article first appeared in EQUUS issue #467, August 2016.