As Many as 1,000 Healthy Pigs Die After Vaccine

As many as 1,000 pigs died in Vietnam this past summer after receiving the first commercial vaccine to prevent African Swine Fever (ASF). The exact number of pig deaths is likely between 750 and 1,342 according to the news service Vietnamnews.

Farmer’s Healthy Pigs Die

The pigs, on a farm in the central province of Phu Yen and at least two other provinces, received the NAVET-ASFVAC vaccine, co-developed by the Vietnamese Navetco company and the U.S. Agricultural Research Institute (ARS), which is part of the U.S. Department of Agriculture (USDA). Le Hung Vuong, 57, a pig farmer in Hoa Thinh Dong Commune in Phu Hoa District, said that a few days after receiving the vaccine, all his healthy pigs developed fevers, hemorrhaged and many died.

African Swine Fever, a highly contagious, double-stranded DNA virus, causes hemorrhagic fever and death in pigs but does not affect humans.

First identified in East Africa in the early 1900s, the disease spread from Africa and European nations in the 1960s and 1970s to Brazil and the Dominican Republic in 1978, according to the Animal and Plant Health Inspection Service, a division of the of the USDA.

AFS swept mercilessly across China in 2018, Bloomberg reported, “slashing herds in the world’s biggest producer and consumer of pork, boosting imports and sending meat costs soaring,” and advancing to Europe. Between 2018 and 2020, ASF killed half of China’s pigs.

The virus is now in 73 countries, including in the Dominican Republic and Haiti – U.S. neighbors – though it’s not yet in the U.S.

Pigs die after new vaccine. Image by Michael Strobel from Pixabay
Pigs die after new vaccine. Image by Michael Strobel from Pixabay

An Urgent, Lucrative Vaccine

According to Farm Progress, a study conducted by Iowa State University showed that an ASF outbreak in the U.S. would be devastating. It would immediately close international markets to U.S. pork and lower U.S. live hog prices by 40%-50%.

The U.S. pork industry would lose between $15 billion – $50 billion and 140,000 jobs would be lost after 10 years, according to the study.

The ASF vaccine would have made Vietnam the first country to export an ASF vaccine but the product is now suspended. Navetco, the vaccine co-developer, is under Vietnam’s Ministry of Agriculture and Rural Development.

The “market” for live and attenuated vaccines to prevent AFS and other swine fevers is estimated at $2,724.5 million, according to EIN News.

Players include Merck Animal Health, Ceva, Zoetis Services LLC, Boehringer Ingelheim International and other animal drug-related companies.

The stated need for an effective ASF vaccine, especially as the U.S. braces for – and dreads- an ASF outbreak, helped funding for Genvax, a vaccine startup in Ames, Iowa.

In April, the company received a $145,000 grant from the Foundation for Food & Agriculture Research, to develop a “self-amplifying” ASF vaccine.

Self-Amplifying Vaccines Take Off

Self-amplifying messenger RNA vaccines (saRNA) may be the next step in vaccine development. They “copy” themselves after injection and may represent lower costs because smaller doses are required and storage is easier says Science magazine.

A transgene or “gene of interest” is inserted into the vaccine platform, provoking an antibody response without a need for the whole pathogen to be used, explains Genvax. Self-amplifying has “shown enhanced antigen expression at lower doses compared to conventional mRNA, suggesting this technology may improve immunization,” notes an article in Nature.

The FFAR grant awarded to Genvax specifies collaboration with the USDA’s Agricultural Research Services Plum Island Animal Disease Center, a controversial animal disease research facility off the coast of New York.

The 2005 book, “Lab 257: The Disturbing Story of the Government’s Secret Plum Island Germ Laboratory,” exposed biological meltdowns, infected workers and virus outbreaks at the facility including lab leaks that were seriously underreported by mainstream media.

In August, shortly before the Vietnamese pig deaths, Genvax, received additional funding – $6.5 million from a coalition of meat packers, feed manufacturers and other food supply chain groups to develop its portfolio of self-amplifying vaccines. “As a stakeholder in the pork industry, we feel this is a necessary step in helping prepare for and protect against African swine fever and other emerging diseases,” said Kevin Ladwig, managing director of Johnsonville Ventures, about the funding. Other Genvax investors were the Iowa Corn Growers Association, Summit Agricultural Group and Ag Startup Engine.

Vietnamese Pig Deaths Cast a Cloud Over the First Commercial ASF Vaccine

When news of Navetco’s successful ASF vaccine and the company’s plan to begin the world’s first mass production of such a vaccine broke in January of 2021, stocks doubled. After initial tests, Navetco and ARS scientists wrote in Transboundary and Emerging Diseases in 2021 that the vaccine, “is able to protect pigs against the virulent ASFV [African Swine Fever Virus] isolate currently circulating and producing disease in Vietnam.”

Douglas Gladue and Manuel Borca, co-authors of the Transboundary and Emerging Diseases article and research microbiologists with ARS even took out patents on the vaccine, called ASFV-G-ΔI177L, according to the journal.

Dr. Jianqiang Zhang, associate professor of veterinary diagnostic and production animal medicine at Iowa State University, also lauded the vaccines. ARS scientists “not only identified a gene they could delete to attenuate the virus within the ASF virus’s large and complex genome, but also developed a cell culture-adapted ASF virus strain that could replicate in inoculated pigs but was attenuated and able to induce protection against ASF,” he told the American Veterinary Medical Association in 2021. After the ASF vaccine passed a regulatory test in April, 2022 that showed it did not revert to baseline ASF virulence after injection, Gladue, Borsa and the ARS were even more encouraged.

But after the animal deaths and suspension of the vaccines, Vietnamese officials began conducting investigations and looking for answers. Phùng Đức Tiến, deputy minister of the country’s agriculture and rural development said, “If the vaccine quality was poor, all the vaccinated pigs would die,” Instead, he suspected that the problems occurred during the vaccination process because many rural farmers had bought the vaccine and injected the pigs themselves without the help of an expert or veterinarian consultation.

Dr. Paul Sundberg, the executive director of the Swine Health Information Center in the U.S. and a member of the Swine Innovation Porc African Swine Fever Research Working Group, pointed out after the pig deaths in Vietnam, that initial reports suggested the vaccine worked well and initial safety studies went well.

syringe vaccine. Image by Liz Masoner from Pixabay
Image by Liz Masoner from Pixabay

Damage Control

In September, a Vietnamese agriculture news website announced that successful trials of the ASF vaccine were completed and vaccination against ASF would begin again. Agricultural officials said the hundreds of pigs that died after vaccination in August stemmed from use of the wrong vaccine dosages, vaccinating the wrong aged animals or other procedures not in compliance with Ministry guidelines. A few pigs exhibited “mild fevers” after the trials but mass vaccination will now proceed.

Meanwhile, U.S. pork producers have two fears – that the vaccine they co-developed is ineffective and dangerous and that the devastating African Swine Fever will reach US shores.

Martha Rosenberg

Martha Rosenberg is the Investigative Health Correspondent for NewsBlaze. Martha illustrates many of her stories with relevant cartoons. She was staff cartoonist at Evanston Roundtable.