CNN's Anderson Cooper, Dr. Sanjay Gupta, and WHO technical lead Dr. Maria Van Kerkhove. Source: CNN

The world is "weeks to months" away from knowing what drugs will work to fight Covid-19, said Dr. Maria Van Kerkhove, the technical lead for the World Health Organization's coronavirus response.

The WHO is tracking a number of studies that are trying to determine exactly how many people have been infected around the world, Van Kerkhove said.

According to one study in Germany, the number of people who have antibodies that show they've had the coronavirus infection ranges from 2% or 3% up to 14% of the population, she said during CNN's coronavirus town hall earlier tonight.

"What’s interesting about this is that these numbers, this seroprevalence, is a lot lower than some of the earlier models had predicted that would have suggested that this virus was circulating a lot more, and that much more of the population was already infected." Van Kerkhove said. "So these studies right now are not actually showing us that."

Seroprevalence is the number of people in a population who test positive for a disease.

The WHO is also closely monitoring the hundreds of Covid-19 drug trials.

"Everyone in the world wants to know which drugs, which medications are going to work, which medications are going to save lives," Van Kerkhove said. "Unfortunately, right now, we don't have any evidence one works, yet."

It’s critical that the studies are done and done well, Van Kerkhove said.

"So we can get to the answer that everybody needs," she said. The results, she added, "can't come soon enough." But the world is "weeks to months" from knowing what works.