Public submissions on the application have now closed with the Environmental Risk Management Authority (ERMA).
Acting general manager, new organisms, Geoff Ridley, said a total of 29 submissions had been received.
It is understood four have requested to be heard in person, requiring the scheduling of the hearing.
The application to use the vaccine has been made by the New Zealand Racing Board and the Equine Health Association. They seek to import the Proteqflu and Proteqflu Te vaccines, which contain a genetically modified component.
The application is the first for a conditional release of a GM organism in New Zealand.
Equine influenza (EI) caused major disruption to the Australian horse racing and breeding industries last year, with a knock-on effect for the New Zealand industry, with horses stranded across the Tasman.
The Proteqflu vaccine was used in Australia to control the outbreak, and that country has now been declared free of the disease.
ERMA is preparing an evaluation and review report on the application which will analyse the risks, costs and benefits of the GM vaccine. It will also look at the types of conditions that could be placed on the vaccine if it were to be approved.
This report will be a source of information to a decision-making committee of the authority which will consider potential adverse effects on public safety and health, valued species, societies and communities, the economy, the environment and natural habitats.
The decision-making committee will use information provided by public submissions and other relevant sources as well as the ERMA New Zealand report in reaching its decision.
ERMA New Zealand's responsibility is limited to the GM micro-organism component of the vaccine. Approval to use the vaccine must also be obtained from the New Zealand Food Safety Authority's Agricultural Compounds and Veterinary Medicines group.
The New Zealand Green Party has already voiced its opposition to the vaccine, arguing it would endanger the country's GM-free status.