The rapidly-spreading new coronavirus has put test kits at the center of how infected patients are diagnosed, so they can get treatment quickly.

But there's one issue with these nose and throat-swabbing tests.

The results aren't always accurate.

At the center of the epidemic in Wuhan, some people tested negative, only later to find out that they actually have the disease.

In the U.S., the CDC sent out test kits to public health labs that gave inconclusive results in the verification process.

The unreliability of these tests even forced Chinese health officials to expand how they classify patients, which resulted in a surge of more than 14,000 cases in one day.

They are now including results from test kits and other diagnostic methods like chest scans.

So how do these test kits exactly work, and why are there so many problems?

This government lab in Singapore has produced test kits for the country's public hospitals.

It's also shipped about 10,000 tests to China.

Dr. Sidney Yee leads the team that developed them.

She says most doctors use a type of lab test called RT PCR, which can be used to detect small amounts of pathogens including viruses like HIV.

So this is the gold standard that's being used.

What it does is, it actually directly detects the presence of the pathogen.

It's pretty easy to use.

A doctor collects samples from a patient by swabbing the nose or throat for mucus.

Those swabs are then sent to a lab for a test that detects the genetic material of a pathogen.

The sample is first mixed with reagents in a tube, then put into a machine that duplicates the genetic material.

So if the virus exists, these copies will amplify its presence, confirming that a patient has tested positive for the coronavirus.

Dr. Yee says the first place for error could be at the swabbing stage.

Most of the time, the sampling for COVID-19 comes from a throat swab.

COVID-19 is actually a lung infection disease, so doing the throat swab really depends on how much of the pathogen you're able to capture.

Another place for error is the time it takes for the sample to reach the lab.

The pathogen on the swab is not going to last for many, many hours, so that transportation, the logistics, is also important.

Transportation is a huge hurdle in Wuhan, where the city has been on lockdown since mid-January.

When the sample gets to the lab, what is the infrastructure of the lab that is able to deal with running tests, as well as the expertise and the experience of the lab technicians that are running these tests?

Dr. Yee says the most critical moment for human error is when doctors decide to use the test kit.

For instance, many people have been showing mild symptoms, but that doesn't mean they don't have the pathogen.

It's very hard to make the direct correlation between what our test kit can be used, on which stage of the disease progression, with respect to how much the pathogen is present in the patients.

Just how accurately these test kits are being used is on trial in Wuhan.

Here, hospitals have been overstretched with limited resources.

There are not enough staff to swab patients, and labs are inundated with the backlog of samples that wait to be tested.

There are many, many different steps, and different processes involved in just running a test.

It's not just, with respect to the test kit itself.