Dr Diep presents Avac’s latest data on its ASF vaccine, including claims of protection in sows and against G1–G2 recombinant strains. He noted that cross-protection could vary depending on infection pressure and the level of virus exposure in the field.
Avac says its ASF vaccine may now protect pigs not only against genotype 2 (G2), the strain that has dominated outbreaks in Vietnam since 2019, but also against the newly emerged recombinant genotype 1–2 (G1-2) variant. The company also says the vaccine can be used in breeding sows, provided it is administered at appropriate stages before mating.
For an industry still struggling with ASF, these claims naturally attract attention. Yet farmers remain careful in how they respond to such developments, as the performance of any vaccine ultimately depends on how it is applied under real farm conditions.
To better understand how the vaccine is being used in practice, PigTalks followed up with Avac’s CEO, Dr Nguyen Van Diep, and spoke with farmers who have applied the vaccine on their farms for several years. Their insights offer a closer look at how vaccination performs under farm conditions.
Sow vaccination requires careful timing
While the vaccine formulation itself does not change, its application in breeding herds requires greater attention to timing.
Avac recommends administering the vaccine to sows before mating, when they are not pregnant. “Vaccination during late pregnancy is discouraged, as the vaccine virus may cross the placenta and affect piglet development,” explained Dr Diep.
For replacement gilts or sows entering the breeding herd, the company recommends a two-dose schedule spaced four weeks apart, with mating taking place after vaccination. In subsequent cycles, a single booster before breeding may be sufficient.
“Some large integrated farms in Vietnam are already using a similar two-dose schedule in growing pigs, typically vaccinating at four weeks and boosting again at eight weeks of age,” added Dr Diep.
Farm experience: lessons learned from vaccination
For farmers dealing with ASF over several years, vaccination has gradually become part of herd management, but not without adjustments.
Vu, a pig farmer in the Mekong Delta, recalls that his farm was repeatedly hit by ASF after the first outbreak in 2019. At that time, the farm had around 100 breeding sows and 600 finishing pigs. Following repeated outbreaks, the herd shrank to just 20 sows and about 100 finishing pigs by 2022. Facing mounting losses, the farm began using the ASF vaccine.
However, the first attempts also revealed problems.
“When we vaccinated pregnant sows, we saw abortions and premature births,” Vu said. “After that experience, we changed our approach.”
The farm now vaccinates sows about 20 days before mating and avoids vaccination during pregnancy. Replacement gilts and lactating sows are vaccinated only when herd health conditions are stable.
Vu also emphasizes that vaccination alone is not enough.
“When we vaccinated, we also treated secondary infections and improved nutrition to stabilize the pigs’ health. If you just inject the vaccine without managing the herd condition, it’s not the same.”
Today the farm has gradually expanded again to around 150 sows and 1000 finishing pigs.
Monitoring herd health after vaccination
Another farmer, Nguyen Kim Doan, Vice Chairman of the Dong Nai Livestock Association, who has used ASF vaccines for several years, says vaccination became a necessary step for rebuilding production.
“Without the vaccine, it would be very difficult to restock,” he said.
However, Mr Doan also stresses that herd health management is essential before vaccination begins.
Weak animals should be removed from the vaccination group, and pigs should first receive vaccines for other diseases such as PRRS, APP and Glässer’s disease so that their immune system is not challenged by multiple pathogens at once.
Farmers should also closely observe pigs for 10 to 19 days after vaccination, he said. If pigs develop fever or respiratory symptoms during this period, supportive treatment may be necessary to help them recover.
“The health of the whole herd is what matters,” Mr Doan said. “You cannot assume every pig will pass through that stage on its own.”
Vaccines help, but good farm management remains decisive
For an industry still searching for ways to manage ASF, vaccines naturally draw attention. But the experiences shared by farmers suggest that vaccination is rarely straightforward in the early stages.
Both Vu and Doan say the vaccine can offer protection, though the first attempts were not without difficulties. Vu recalls that vaccinating pregnant sows led to abortions, prompting the farm to adjust the timing of vaccination. Doan also noted that herd health had to be stabilised before vaccination, including addressing other diseases and removing weaker animals from the herd.
Over time, both farms adapted their approach. Vaccination was combined with closer monitoring of herd health, improved nutrition and tighter control of secondary infections.
Their experiences suggest that, under farm conditions, the effectiveness of vaccination depends not only on the vaccine itself but also on how it is applied within the broader management of herd health.
By Ha Thu – PigTalks
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