"These farms are often open, rustic, with access to bats that are abundant in the region," he said. A spill could have occurred on one of the farms and an infected human could have infected others on the Wuhan market.
There is also the question of where the virus evolved its ability to easily pass from human to human. That could have happened in animals, Dr. Andersen said, which means it would have come up ready to cause a pandemic. Or it could have circulated in humans in a less efficient way, from the virus's point of view. Then his human pandemic team evolved.
In any case, Dr. Andersen said, although the current pandemic is the war we are waging, there is no doubt that another could come. This was not a surprise, he noted. He said, "We hear that no one could have predicted a pandemic," he paused, "except for everyone who works on infectious diseases."
However, he admitted that before the current pandemic, his main concern was not the coronavirus family. "If I had to guess earlier," he said, "I would have said the flu."
Dr. Andersen said that the best defenses for the future would be widely effective vaccines, such as a universal flu vaccine and a SARS-like coronavirus vaccine.
Monitoring animal sources and understanding how viruses evolve is essential, but, he said, it would not prevent the next pandemic.
As for finding the animal that was the intermediate host, it can happen. But without viral genetic material from the earliest human or animal cases with very similar viruses, including animals that might have been present in the Wuhan seafood market, that search is very difficult.