Frequently Asked Questions

1-Will the vaccine be of benefit if there is an active     flu infection on the premises?

This has not been tested. In general, live virus vaccines are thought to stimulate a more rapid immune response than killed virus vaccines. In addition, the live virus stimulates non-specific responses (such as interferon production) very quickly that could also help reduce infection by a wild-type virus. The fact that Flu Avert^® I.N. vaccine is administered intranasally, at the most likely site of infection by a wild-type virus, makes it more likely that these non-specific responses could reduce infection by the wild-type virus. So it is theoretically possible that Flu Avert^® I.N. vaccine could help in these situations.

If you use Flu Avert^® I.N. vaccine during an outbreak, it would be a good idea to collect a nasal swab from each horse just before vaccination. Even though you will not know if the horse is shedding virus before you vaccinate, the results could help you explain to your client why the horse got sick after vaccination, if that occurs.

2- Is it safe to use the vaccine in a horse that may      be infected with influenza virus?

There is no scientific reason to think that using Flu Avert^® I.N. vaccine in a horse already infected with influenza will increase the risk of disease for that horse or other horses in contact with it. In 1994, Dr. Julius Youngner and Dr. Patricia Whitaker-Dowling (University of Pittsburgh School of Medicine) and others reported on a study¹ in 27 adult human volunteers. In that study, 13 people were given a mixture of a cold-adapted human influenza vaccine virus and a wild-type human influenza virus, with no indication of any untoward effect. The data demonstrated that administration of cold-adapted influenza A virus to humans at the time of wild-type virus infection is a safe procedure.

3- What is the best strategy for controlling influenza      in horses?

There should be no question that the best strategy is to routinely vaccinate all horses before they are at any risk of exposure. Especially now that we know outbreaks are occurring, vaccinating all horses with Flu Avert^® I.N. vaccine ahead of these outbreaks clearly offers the most effective prevention strategy. In addition, primary immunity is established from a single intranasal vaccination with Flu Avert^® I.N. vaccine. The ideal plan is to vaccinate the horse at least 2 weeks before exposure.

It should be noted that in previous outbreaks in Kentucky, New Jersey and New York, the horses that were previously vaccinated with Flu Avert^® I.N. vaccine were reported as not getting sick and were performing. But if an influenza outbreak has already occurred, vaccinating horses not yet showing clinical signs during an outbreak may help, and there should be no concern about safety.

¹ Youngner JS, Treanor JJ, Betts RF, Whitaker-Dowling P.: Effect of Simultaneous Administration of Cold-Adapted and Wild-Type Influenza A Viruses on Experimental Wild-type Influenza Infection in Humans. Journal of Clinical Microbiology. Mar. 1994, p.750-754