Vietnam’s Domestic ASF Vaccine After Field Rollout: Effectiveness, Limitations & Lessons for Proper Use

African swine fever (ASF) remains one of the biggest threats to Vietnam’s pig farming industry. Since ASF first appeared in Vietnam in 2019, millions of pigs have had to be culled, causing major economic losses for the livestock sector. In this context, Vietnam’s development and use of a domestically produced ASF vaccine marks an important step in adding another disease prevention tool.

However, the ASF vaccine is not a replacement for biosecurity. After the field rollout phase, the key question is not only whether the vaccine works, but under what farm conditions, for which groups of pigs, and with what usage process it can be effective.

What is AVAC ASF LIVE, and why did Vietnam develop a domestic ASF vaccine?

Technical characteristics of AVAC ASF LIVE

AVAC ASF LIVE is a freeze-dried, live attenuated vaccine used to prevent African swine fever. It was researched and produced by AVAC Vietnam Joint Stock Company. It is one of the ASF vaccines that has been commercialized and used under field conditions, while many other ASF vaccines globally are still in the research, testing, or evaluation stage.

According to AVAC’s product information, the vaccine contains the attenuated ASFV strain ASF-G-ΔMGF, cultured on the DMAC cell line developed by AVAC. The vaccine is indicated for active immunization against African swine fever in healthy market pigs from 4 weeks of age and older.

The product is administered by intramuscular injection. Each dose after reconstitution is 2 ml. The vaccine must be reconstituted with the accompanying Avac Diluent and should not be reconstituted with any other diluent unless instructed by the manufacturer or veterinary authorities. It should be stored at 2–8°C, protected from direct sunlight, and used according to the manufacturer’s instructions.

One important point to emphasize is that AVAC ASF LIVE should not be used indiscriminately for every group of pigs. Farmers should check the current product leaflet and consult veterinary staff before vaccination, especially if they want to use it for groups outside the standard indication, such as breeding pigs, sows, or breeding boars.

Protection mechanism and limitations that need to be understood correctly

A live attenuated ASF vaccine is expected to stimulate an active immune response, helping pigs better resist ASF virus after vaccination in the right target group, according to the correct procedure, and after sufficient time for immunity to develop.

However, immunity does not appear immediately after vaccination. According to product information, pigs usually need around 2–4 weeks after one dose to develop protective immunity. The stated duration of protection may last up to around 5 months. During the first 2–4 weeks after vaccination, the herd still needs to be protected strictly through biosecurity, because vaccination does not mean the pigs are fully protected right away.

In addition, the vaccine cannot work well if pigs have already been infected with field ASF virus, are in the incubation period, are under severe stress, are malnourished, are co-infected with other diseases, or are living in an environment with very high pathogen pressure.

The rollout context of Vietnam’s domestic ASF vaccine

AVAC ASF LIVE has been licensed for circulation in Vietnam and has been used in real-world conditions. The initial rollout focused on farms with suitable monitoring capacity, proper vaccine storage conditions, a relatively good biosecurity foundation, and supervision from professional veterinary staff or authorities.

This rollout approach reflects the nature of ASF vaccination: it is a disease prevention tool that must be used under controlled conditions. It is not a solution for uncontrolled mass vaccination. A live attenuated vaccine requires stricter storage, reconstitution, vaccination technique, and post-vaccination monitoring than many common veterinary vaccines.

After the field rollout phase, the most important lesson is that vaccine effectiveness depends on the entire management system around it: herd health status, biosecurity, vaccine storage, injection technique, timing of vaccination, and post-vaccination monitoring.

How should the field effectiveness data of Vietnam’s domestic ASF vaccine be understood?

Results under controlled conditions and field conditions

Under experimental or controlled monitoring conditions, AVAC ASF LIVE has been reported to show promising protection and immune response results. However, when applied in the field, farm conditions vary greatly. Some farms have strong biosecurity, while others still have many gaps. Some herds are healthy, while others are under pressure from PRRS, PCV2, parasites, or mycotoxins in feed.

For this reason, results from trials should not be understood as a guaranteed level of protection for every farm. In the field, the vaccine usually works better when pigs are healthy, vaccinated in the right target group, the vaccine is stored at the correct temperature, reconstituted with the correct diluent, injected using proper technique, and the farm has a strong enough biosecurity foundation.

In contrast, on farms with weak biosecurity, circulating pathogens, new pigs introduced without quarantine, uncontrolled feed or drinking water, or vaccination carried out when suspicious clinical signs are already present, vaccination results may be lower than expected.

The key point is this: no ASF vaccine provides 100% absolute protection under all conditions. The vaccine is an additional layer of defense, not a replacement for biosecurity.

Comparing AVAC ASF LIVE with other ASF vaccines or ASF vaccine candidates

AVAC ASF LIVE should not be compared with “imported ASF vaccines” in a broad or absolute way unless there is clear legal information about the product, country of origin, marketing authorization, and permitted use conditions in Vietnam. A safer comparison is to compare AVAC ASF LIVE with other ASF vaccines or ASF vaccine candidates being studied around the world.

Criteria	AVAC ASF LIVE	Other ASF vaccines / ASF vaccine candidates
Origin	Vietnam	Depends on the product or country of research
Vaccine type	Live attenuated, freeze-dried	May be live attenuated, vector-based, subunit-based, or another platform depending on the study
Strain / technology	ASF-G-ΔMGF, cultured on the DMAC cell line according to AVAC information	Depends on each product or candidate
Target use	Healthy market pigs from 4 weeks of age and older, according to current guidance	Depends on the registration dossier and approval of each product
Data in Vietnam	Has domestic use data and continues to be monitored	Should not be assumed if there is no field data in Vietnam
Storage conditions	2–8°C, protected from direct sunlight	Depends on the product
Important note	Do not use outside the product indication without professional guidance	Approval documents and official instructions must be checked

The advantage of a domestic vaccine is greater control over supply, distribution, and use data under Vietnamese conditions. However, to conclude long-term field advantages, data still needs to be monitored across more regions, farm models, and different levels of epidemiological pressure.

Cases where the vaccine may not work effectively: common causes

Immune failure after ASF vaccination may occur if farmers treat the vaccine as an “absolute shield” and ignore the basic conditions needed for it to work. Common causes include:

Vaccine effectiveness may be affected by incorrect storage or reconstitution

AVAC ASF LIVE must be stored at 2–8°C and protected from direct sunlight. If the cold chain is interrupted, if the vaccine is left at room temperature for too long, or if the reconstituted vaccine is not used within the recommended time, effectiveness may be affected.

After reconstitution, the vaccine must be used within the time instructed by the manufacturer. According to product information, the reconstituted vaccine should be used within 3 hours. Do not use any diluent other than the accompanying diluent or a diluent recommended by the manufacturer.

Vaccination is given to pigs in the incubation period or already infected with ASF

The vaccine does not treat ASF. If the herd already has pigs infected with field virus or pigs in the incubation period, vaccination no longer provides preventive value and may complicate later monitoring and evaluation. When ASF is suspected, the priority should be isolation, reporting to veterinary authorities, sample collection for testing, cleaning and disinfection, and handling according to professional guidance.

The herd is co-infected or immunocompromised

Pigs affected by PRRS, PCV2, heavy parasitic infection, malnutrition, heat stress, or mycotoxins in feed may respond poorly to vaccination programs in general. Before implementing ASF vaccination, farms need to stabilize herd health, control underlying diseases, and improve farming conditions.

Pathogen pressure on the farm is too high

If ASF virus is already present in the farm environment, equipment, transport vehicles, carcass disposal areas, or surrounding areas, the vaccine will have difficulty performing as expected. When pathogen pressure is too high, biosecurity is the first layer of defense.

Farm-level factors that determine the effectiveness of Vietnam’s domestic ASF vaccine

Minimum biosecurity conditions needed before vaccination

The ASF vaccine does not work in isolation. Its effectiveness depends heavily on the farm’s biosecurity foundation, the herd’s health status, pathogen pressure in the environment, and proper compliance with the product instructions. This is also a principle emphasized by Vietnamese livestock and veterinary authorities and WOAH in ASF control.

Before deciding to vaccinate, farmers should assess whether their farm meets the following minimum conditions:

• There is a fence or boundary to control the movement of people, vehicles, and animals into and out of the production area.
• There is a disinfection pit or disinfection procedure at the gate, barn entrance, and changing area.
• There is a quarantine area for newly introduced pigs before they join the main herd.
• Wild animals, dogs and cats, rodents, insects, people, vehicles, and equipment that may carry pathogens into the farm are controlled.
• Feed, drinking water, and farming tools are not contaminated by external sources.
• There is a clear process for handling dead animals, waste, and wastewater.
• There are records of pig entry, pig exit, illness, mortality, vaccination, and veterinary drug use.

None of these conditions will appear automatically after vaccination. If a farm does not meet these basic requirements, the vaccine may become an additional cost without solving the root cause.

Herd health status before vaccination

The pigs’ immune systems are a deciding factor in whether the vaccine works well. Before ASF vaccination, farms need to check the following issues:

PRRS and other immunosuppressive diseases

Farms with circulating PRRS or unstable respiratory or reproductive disease problems may respond more poorly to vaccination programs in general. Herd health should be stabilized before ASF vaccination is implemented.

Malnutrition and stress

Pigs lacking protein, minerals, or vitamins, or pigs under stress from heat, humidity, high stocking density, or poor barn conditions, may not develop a full immune response even if the injection technique is correct.

Parasites

Heavy worm, fluke, or parasite infections consume energy and affect immunity. Regular deworming according to veterinary guidance is an important part of herd health management.

Mycotoxins in feed

Mycotoxins in feed can affect immunity without obvious clinical signs, especially in hot and humid climates. Farms need to control raw material quality, feed moisture, and storage conditions.

Lessons from the ASF vaccine rollout among pig farmers

Common mistakes in vaccine storage and reconstitution

Mistakes to avoid include:

• Taking the vaccine out of the refrigerator too early before vaccination.
• Leaving the vaccine at room temperature for too long.
• Reconstituting the vaccine with well water, tap water, or a diluent not specified in the instructions.
• Reusing leftover vaccine after the vaccination session.
• Storing the vaccine together with disinfectants or materials that may affect vaccine quality.
• Failing to check the expiry date, batch number, vial condition, and diluent before vaccination.

The simplest message for farmers is: the vaccine must be kept at the correct refrigerated temperature, reconstituted with the correct diluent, injected at the right time, and used up within the recommended period.

Mistakes in vaccination schedule and pig selection

Mistakes to avoid include:

• Vaccinating pigs that are not at the correct age or do not belong to the target group indicated in the instructions.
• Vaccinating pigs that are feverish, not eating, having diarrhea, coughing, or showing signs of illness.
• Vaccinating while the farm has suspected ASF cases.
• Reducing the dose without guidance in order to save cost.
• Combining the vaccine with other vaccines or changing the vaccination schedule without professional guidance.
• Re-vaccinating or giving booster doses without recommendations from the manufacturer or veterinary authority.

According to current product information, AVAC ASF LIVE is indicated for healthy market pigs from 4 weeks of age and older. Farmers should not use the vaccine on breeding pigs, sows, or breeding boars if the product has not been officially approved for these groups or if there is no specific guidance from professional authorities.

Post-vaccination herd monitoring

After vaccination, farmers need to monitor the herd more closely, especially during the first 7 days.

Some mild reactions may occur, such as slightly reduced feed intake, a short-term mild fever, or brief lethargy. However, if any of the following signs appear, farmers should immediately report them to veterinary staff:

• Persistent high fever.
• Pigs lying lethargically and unable to stand.
• Skin hemorrhage, cyanosis, or widespread loss of appetite.
• A rapid increase in the number of pigs showing symptoms.
• An abnormal increase in mortality.
• Symptoms suspected to be ASF in a vaccinated herd.

Post-vaccination records are not just an administrative requirement. They are data that help farmers and veterinary staff distinguish between normal reactions, process errors, underlying disease, or the possibility that the herd had already been infected with field virus before vaccination.

Step-by-step ASF vaccination guide for smallholder pig farmers

Step 1: Assess herd status and farm conditions before vaccination

Before ordering the vaccine, farmers should answer the following questions:

• In the past 30 days, has the herd had any cases of fever, loss of appetite, diarrhea, hemorrhage, abnormal death, or clear reduction in weight gain?
• Has the farm recently introduced new pigs without completing the required quarantine period?
• Is the area around the farm currently under ASF risk warning from veterinary authorities, or is there a nearby outbreak?
• Are PRRS, PCV2, respiratory disease, or intestinal disease currently circulating on the farm without control?
• Has the farm implemented deworming, parasite control, and mycotoxin control?
• Does the farm have the capacity to store the vaccine at 2–8°C?
• Is there a veterinarian or trained person available to support the vaccination process?

If any answer indicates a risk, the issue should be handled before vaccination is scheduled. Farmers should not vaccinate against ASF simply because there is an outbreak in the surrounding area if their own farm does not yet meet the required biosecurity and post-vaccination monitoring conditions.

Step 2: Prepare the vaccine, tools, and vaccination process

Before vaccination, prepare the following:

• Vaccine that is within its expiry date, has the correct batch number, and remains in good condition.
• The accompanying Avac Diluent or another diluent that follows the manufacturer’s instructions.
• A cold box or vaccine storage tool to maintain proper temperature throughout the vaccination process.
• Clean needles and syringes of the correct size.
• A record book for vaccination date, vaccine batch number, number of vaccinated pigs, and person performing the vaccination.
• A plan for handling abnormal reactions according to professional guidance.

Do not use medication for shock reactions or other supportive drugs without professional guidance. A veterinarian or trained person should support the vaccination process, especially for smallholder farms that do not yet have experience using ASF vaccines.

Step 3: Administer the vaccine and keep monitoring records

During vaccination, follow these rules:

• Administer the vaccine via the route specified in the product leaflet.
• Do not vaccinate pigs that are feverish, not eating, or showing signs of disease.
• Do not vaccinate a herd suspected of having ASF.
• Do not reduce the dose without guidance.
• Do not reconstitute the vaccine with a different diluent.
• Do not use reconstituted vaccine beyond the recommended time.
• Record ear tag number or pig ID if available, vaccination date, vaccine batch number, person performing the injection, and any post-vaccination reactions.

After vaccination, the herd should be observed at least twice a day during the first 7 days. The 2–4 week period after vaccination is especially important because protective immunity has not yet fully developed.

Self-monitoring checklist after ASF vaccination

After vaccination, farmers can use the checklist below for basic monitoring:

• The pigs continue eating and drinking relatively normally after the initial mild reaction period.
• There is no persistent high fever or rapid spread of ASF-like symptoms in the herd.
• There is no abnormal increase in mortality.
• There is no severe or prolonged inflammation at the injection site.
• No new outbreak occurs on the farm.
• The farm continues to disinfect people, vehicles, tools, and barn areas.
• No new pigs are introduced into the herd immediately after vaccination without a clear quarantine plan.
• Records are kept fully, including vaccination date, vaccine batch number, number of vaccinated pigs, and post-vaccination condition.

This checklist is only an initial monitoring tool. Evaluation of post-vaccination response and protective effectiveness should be based on clinical monitoring, epidemiological data, and appropriate testing according to veterinary authority guidance.

FAQ about Vietnam’s domestic ASF vaccine

What percentage of field protection does AVAC ASF LIVE provide?

Under experimental or controlled monitoring conditions, AVAC ASF LIVE has been reported to show promising protection and immune response results. However, the protection rate in the field may differ depending on farm conditions, herd health, pathogen pressure, biosecurity, and vaccine handling technique.

Therefore, one single protection percentage should not be applied to every farm. The correct understanding is this: the vaccine can be an important prevention tool if it is used for the right target group, through the right process, and on a farm with a strong enough biosecurity foundation.

Do smallholder farmers have the necessary conditions to use Vietnam’s domestic ASF vaccine?

Smallholder farmers may consider using the ASF vaccine if they meet minimum conditions: they can control movement into and out of the barn area, store the vaccine at the correct temperature, have support from veterinary staff or a trained person, and have a plan for post-vaccination monitoring.

Smallholder farms with free-ranging pigs, fully open barns, no control over people, vehicles, or animals entering the farm, or no capacity to store the vaccine at 2–8°C will have difficulty achieving the expected effectiveness. In these cases, biosecurity should be strengthened first.

At what age can pigs receive AVAC ASF LIVE?

According to current product information, AVAC ASF LIVE is indicated for healthy market pigs from 4 weeks of age and older. Farmers should check the product leaflet or ask veterinary staff directly before vaccination, because instructions may be updated based on licensing documents and new monitoring results.

Farmers should not use the vaccine on breeding pigs, sows, or breeding boars if the product has not been officially approved for these groups or if there is no specific professional guidance.

Should the vaccine be used if the farm has pigs suspected of ASF infection?

No. The vaccine should not be used when the farm already has pigs suspected of ASF infection. When pigs have high fever, loss of appetite, hemorrhage, cyanosis, abnormal death, or signs suspected to be ASF, the priority is immediate isolation, reporting to local veterinary authorities, sample collection for testing, cleaning and disinfection, and handling according to professional guidance.

The ASF vaccine only has preventive value when it is given before the herd is exposed to clear disease pressure and when the herd is healthy.

How long after AVAC ASF LIVE vaccination does protective immunity develop?

According to product information, pigs usually need around 2–4 weeks after one dose to develop protective immunity. The stated duration of protection may last up to around 5 months. During this period, farmers must continue strict biosecurity, because vaccinated pigs are not fully protected immediately.

Is an ASF vaccine booster needed?

Farmers should not give booster doses without guidance from the manufacturer or veterinary authorities. They need to follow the current product leaflet on dosage, target animals, duration of protection, and usage schedule.

If there are any changes in the usage instructions, farmers should confirm directly with local veterinary staff, the manufacturer’s representative, or official guidance documents before applying them.

Key points to remember when using Vietnam’s domestic ASF vaccine

Vietnam’s domestic ASF vaccine is an important tool in the country’s African swine fever control strategy, but it only delivers value when placed within a complete management system. Vaccine effectiveness does not lie only in the vial. It depends on the entire process before, during, and after vaccination.

Pig farmers need to remember five core principles:

1. Vaccinate the right target group.
2. Vaccinate only when the herd is healthy.
3. Store and reconstitute the vaccine according to instructions.
4. Maintain strict biosecurity.
5. Monitor and record the herd fully after vaccination.

The vaccine does not replace fencing, disinfection, quarantine, control of new pig entry, waste handling, or disease surveillance. If these defense layers are weak, the vaccine will have difficulty creating the expected protection.

On the other hand, if used correctly on farms with a good biosecurity foundation, Vietnam’s domestic ASF vaccine can become a valuable supporting tool, helping pig farmers become more proactive in disease prevention and reduce the risk of losses caused by African swine fever.

Stay Updated on Vaccine and Livestock Disease Prevention Solutions at VIETSTOCK 2026

VIETSTOCK 2026 – Vietnam’s Premier International Feed, Livestock and Meat Processing Industry Show – is expected to bring together more than 300 brands and 13,000 trade visitors from many countries, including manufacturers and distributors of vaccines, veterinary medicines, biosecurity equipment, and pig herd health management solutions. This is an opportunity to:

• Meet directly with vaccine, veterinary medicine, and disease prevention solution providers operating in the Vietnamese market
• Discuss disease prevention protocols, epidemiological updates, and biosecurity solutions for different farm scales with veterinary experts and businesses
• Connect with regulatory agencies and industry associations to stay updated on the latest policy directions in disease control, especially for ASF, avian influenza, and other dangerous diseases

Time: October 21–23, 2026

Venue: Saigon Exhibition and Convention Center (SECC), 799 Nguyen Van Linh, Ho Chi Minh City.

Register now to seize opportunities for growth and networking in the livestock industry:

Visitor registration: https://www.vietstock.org/en/online-registration-2/

Event website: https://www.vietstock.org/en/

Contact information:

• Exhibiting: Ms. Sophie Nguyen – [email protected]
• Group Delegation Support: Ms. Phuong – [email protected]
• Marcom Support: Ms. Anita Pham – [email protected]