Viet Nam says it has a vaccine for African Swine Fever.
Officials at the National University of Agriculture say the vaccine worked in research trials.
But others are skeptical.
"We need different phases of clinical trials, first in an experimental setting with controlled exposure, and then a field trial with natural exposure to the virus, and that cannot be a small trial," said Dirk Pfeiffer, a professor of veterinary epidemiology at the City University of Hong Kong.
Viet Nam has lost 2.9 million of its 30 million hogs to African Swine Fever and some are now saying that China has lost twice as many as its government estimate of 20 per cent of its hogs.