The number of infected properties officially stood at 4011 yesterday, with another 850 considered either "suspect" or "dangerous contact".
NSW disease experts monitoring the spread of the disease predicted that the number of infected properties would reach about 4000.
NSW chief veterinary officer Bruce Christie confirmed that horses in Dubbo, Armidale, Parkes-Forbes, Wellington, Mudgee and Barmedman buffer zones are now receiving vaccinations. They include ponies, donkeys, polocrosse, draft and working horses.
In Wellington, where a buffer zone has established following a recent outbreak, 48 miniature horses and more than half a dozen donkeys have been vaccinated.
Veterinary teams fully decontaminate after visiting each horse property to ensure equine flu is not spread further.
"It's a time-consuming process as the teams have to take swabs and blood tests before horses are vaccinated and mirco-chipped."
Mr Christie reiterated that vaccination will not stop horses becoming infected with flu or replace the need for strict biosecurity.
"Vaccination will reduce the severity of clinical signs of horse flu, enabling faster recovery from infection and reduce the quantity of virus shed by infected horses, lessening the chance of spreading the virus," he said.
"Biosecurity measures must continue - even when immunity has developed - until all infected animals have stopped shedding the virus.
Nine vaccination centres in the state have either opened or are about to.
No mass vaccination programme is planned at this stage. Successful containment will allow the disease to "burn itself out", a spokesman said.
Horses in buffer zones have the highest priority for vaccination, followed by uninfected horses within existing restricted areas.
"At least 50% of the available vaccine doses have been allocated for use in the buffer zones," the spokesman added, "with the bulk of the remainder allocated to horses in restricted areas".
Most horses in the buffer zones are recreational or pleasure horses.
In Queensland, where the number of infected properties stood at 928 yesterday, Primary Industries Minister Tim Mulherin said free movement of horses within Queensland's red zone was possible by Christmas if the strategy to contain equine influenza to the south-east remains on track.
The Christmas goal was achievable if all Queenslanders involved in the equine industry played their part in ensuring all quarantine safeguards were adopted and upheld.
He said with a horse standstill in place, the greatest threat to equine influenza spreading beyond the red zone was through human contact with horses and human failure to properly decontaminate.
He said he expected the buffer zone around south-east Queensland to be fully effective from mid to late December, after administration of the second booster dose.
Mr Mulherin said he had asked his department to look at ways of increasing security and surveillance of the border between the red and green zones.
While movement restrictions would be loosened in the red zone at Christmas, there will continue to be strict controls between the red to green zones.
Meanwhile, a new steering committee to help the sport and recreation horse industry get back on its feet met for the first time yesterday.
The committee includes representatives from the Horse Industry Council (Queensland), Equestrian Queensland, Pony Club Association, Sport and Recreation Queensland, the Department of Primary Industries and Fisheries, Communities, and Tourism, Regional Development.
"The sports horse industry is very valuable to Queensland - not only economically through export revenue and job creation but also through their contribution to the Queensland lifestyle," Mr Mulherin said.
"But with so many diverse groups, everyone needs to come together with the common goal of how to reduce the spread of the disease and get horse events back up and running."
Mr Mulherin said as well as an opportunity to bring horse sport industry groups under the one banner, the steering committee would develop and roll out an equine flu economic recovery plan.