African swine fever vaccines yet to be fully understood

In mid-November, the prime minister sent an express dispatch to ministries, ministerial-level agencies, agencies under the government, people’s committees of provinces, and centrally-run cities on the implementation of solutions to prevent and control African swine fever (ASF).

African swine fever (ASF)

The dispatch came amid continuing outbreaks of the dangerous infectious disease. According to a report from the Ministry of Agriculture and Rural Development (MARD), since early this year, over 530 ASF outbreaks have appeared nationwide, forcing the cull of over 20,000 pigs in 44 cities and provinces, especially in Lang Son, Cao Bang, Son La, Quang Binh, and Dak Lak.

Deputy Prime Minister Tran Luu Quang, on behalf of the government, asked for an urgent review and organise vaccination to prevent dangerous infectious diseases in pigs such as foot-and-mouth disease, and blue ear, especially the ASF vaccine for pig herds in localities that have had or are currently having epidemics, or are at risk.

High-risk animals include pigs that have been vaccinated, but the dose has expired or is about to. The plan is to ensure the rate reaches over 80 per cent of the total herd at the time of vaccination.

“We must continue coordinating with international organisations and countries in supporting Vietnam in disease prevention and control, research, and production of ASF vaccines for sows, males, and breeds,” DPM Quang said.

Vietnam was the first country in the world to embark on the approval of various ASF vaccines. Currently, the country has given marketing authorisation for vaccines from the companies AVAC and Navetco.

Dabaco, the third vaccine producer, also announced plans to have a vaccine developed.

In October, AVAC entered into an export cooperation agreement with five partners from the Philippines, Indonesia, Malaysia, India, and Myanmar.

In the domestic market, although the MARD asserted that the vaccines were eligible for circulation and use nationwide, a number of livestock companies are still concerned about the efficacy of the products.

A representative of a foreign-invested livestock company told VIR, “We have yet to be absolutely convinced by the ASF vaccine. The products’ safety is ensured, but we are not sure about the efficacy. To date, we have just been allowed to organise vaccinations at a few farms for pilot testing. We are still prioritising biosecurity measures.”

“The vaccine is recommended for sows only, meanwhile the risk of infection of this virus is high. This is one of the biggest disadvantages of ASF vaccines.”

According to the representative, the information about efficacy of the vaccine is also unclear. Some local media reports stated that more than 650,000 doses of the vaccines were tested on hog herds in 40 provinces, with an efficacy rate of 95 per cent.

According to the June 2023 Swine Health Information Center Global Disease Monitoring Report, the AVAC ASF LIVE vaccine has shown promise in clinical trials conducted since March 2022 and has been used in some pig farms after receiving conditional distribution approval in July 2022.

The report states that preliminary results on over 600,000 pigs from 545 pig farms, in partnership with livestock company C.P. Vietnam, demonstrated over 93 per cent of the technical requirements as a result of sample tests on almost 6,000 randomly selected pigs.

“The 650,000 pigs combined with over 600,000 pigs at C.P. Vietnam Group means the testing result is not convincing enough. In addition, the evaluation of vaccines’ efficacy involves many factors, for example, safety, genetic stability of continuous clinical replication, characteristics of horizontal transmission, and vertical transmission, all affecting pig farming productivity,” the representative said.

A new draft standard for the production of safe and effective vaccines against ASF was proposed in the September report from the Biological Standards Commission under the World Organisation for Animal Health.

The organisation urges vaccine manufacturers and members to consider these draft standards when developing and evaluating ASF vaccine candidates for regulatory approval, and to provide their comments.

Made-in-Vietnam African swine fever vaccines exported to five countries Vietnam has successfully produced and officially exported African swine fever vaccine of AVAC Vietnam Joint Stock Company to five countries, including Philippines, Indonesia, Malaysia, India, Myanmar.