A shortage of monkeys is posing a problem for COVID-19 vaccine research

Scientists worldwide are racing to develop a COVID-19 vaccine — with optimistic estimates that say one could be ready by the end of the year. One crucial element for these researchers is in high demand and short supply: monkeys.

Last year the U.S. imported nearly 35,000 monkeys for medical research, and 60% of them came from China. But China stopped exporting monkeys once the pandemic started, and now researchers are scrambling to find primates for the final phases of testing.

Sarah Zhang covered this for The Atlantic, and she says China enforced a blanket ban on wildlife trade due to the pandemic. 

She notes that China is a major exporter of monkeys for biomedical research worldwide. “Monkeys are native to China, first of all. They also have these large breeding facilities. Breeding monkeys is an expensive, time-intensive process. And China has really invested in that infrastructure.” 

She says some people suspect China is possibly saving these monkeys for their own research.

The U.S. does have its own breeding facility, and a big part of that is the National Primate Research Centers, which are funded by the National Institutes of Health. However, the monkey breeding pool in the U.S. is a lot smaller than China’s, and monkeys are not native to America, so they still have to be acquired abroad, Zhang says. 

Animal rights activists have also been critical of primate research in the U.S., and they’ve lobbied airlines to bring in monkeys (for research) from places beyond China. 

Monkeys are typically the last stop before human trials. Zhang explains, “The way it usually works is that you might start first with cells in a petri dish. And if your drug, for example, is promising, you might go to a small animal, so something like a mouse or a hamster. And if that still looks promising, then you finally go into monkeys. And then you finally go into humans.”

How worried are COVID-19 researchers about this monkey shortage? Zhang says larger companies have the clout to buy these monkeys. Researchers who’ve been able to get the monkeys they wanted — those monkeys came from other parts of the world or were used in past research such as toxicology studies. 

Is there any other way to effectively do this research without involving monkeys? 

Zhang says on the one hand, researchers are trying to think of creative ways to use fewer animals. “When you do experiments, you usually have to treat one group of animals with your drug. And then another group is the control, and you don't give them anything. So finding ways to like reuse these control animals, so then you can at least have fewer animals being used.”

On the other hand, some scientists are thinking about skipping primate trials entirely. “If, for example, it's a vaccine candidate where you have really good data from small animals, or it's something that looks similar to something that's been in humans before, maybe you don't need to do that primate trial first, you can go straight into humans. I think that's really going to be a case by case basis,” Zhang says. 

The COVID-19 pandemic is an emergency, so human and monkey trials are happening at the same time, she says. 

She adds, “On the other hand, I think some private scientists I spoke to, they sort of felt like this pandemic and sort of this need for a vaccine has made very clear the stakes of what primary research can be. One example that they mentioned is that we want kids to be able to take this vaccine, right? I think there are probably a lot of adults who might say they want to volunteer, but then how do we run these trials in kids? And maybe one of the steps is to study it in young monkeys first. And if that's the case, then maybe we can go into children.” 

Zhang says right now, there’s hope that China will start exporting monkeys again but it’s unclear, and meanwhile, researchers are trying to make do with the monkeys they have and source them from other countries. 

Finally, monkeys are also expensive. “One of the scientists I spoke to mentioned that a rhesus macaque costs around $5,000. And because of recent demand, it's now about twice that, so about $10,000 a monkey.”

— Written by Amy Ta, produced by Rebecca Mooney



  • Sarah Zhang - staff writer at The Atlantic who covers science and health