As a rare respiratory virus continues to sicken children around the country, spreading to hundreds in almost every state in a matter of weeks, the actual number of infections has remained a mystery. That is because the volume of possible cases requiring testing has been so large — and the testing process so, so slow — that public health officials are still working through a backlog that stretches back about a month.

This is about to change, as a new form of testing announced Tuesday by the Centers for Disease Control and Prevention should provide an up-to-date number of people infected with enterovirus 68, the rare virus strain, which is also known as EV-D68..

Of course, this means the number of confirmed infections is about to surge, which will only increase anxiety about a virus that has been linked to at least six deaths. Still, even as the CDC acknowledged that the number of cases “will likely increase substantially in the coming days,” the agency stressed that this didn’t mean there was a sudden surge in enterovirus infections.

“These increases will not reflect changes in real time or mean that the situation is getting worse,” the CDC said in a statement.

Rather, the higher numbers expected sometime next week will be due to the new testing, which will screen more than four times as many samples each day as the older lab tests.

So far, about half of the samples sent to the CDC for testing have been checked. These tests have found nearly 700 confirmed cases in 46 states and Washington, D.C., since the virus began sickening children in mid-August, according to the CDC.

The positive test results were found in about 60 percent of the 1,100 samples that have been tested from August through Oct. 10. And there are still about 1,000 samples that need to be tested, many of them received over the last month.

“CDC has received substantially more specimens for enterovirus lab testing than usual this year, due to the large outbreak of EV-D68 and related hospitalizations,” Anne Schuchat, director of the CDC’s National Center for Immunization and Respiratory diseases, said in a statement Tuesday.

The older test, which had been used by the CDC for nearly a decade, required more time and labor, and it only allowed about 40 tests to be conducted each day. This also took several weeks, Schuchat said. The new test is shorter, has fewer steps and actually lets the CDC check out multiple samples at the same time. The CDC said it will now be able to conduct about 180 tests each day and have results in just a few days.

The rare enterovirus was first identified as a growing problem for children late in the summer. Enteroviruses are quite common and are responsible for between 10 and 15 million infections each year, typically in the summer and fall, according to the CDC. This particular strain, which causes breathing problems, was first isolated in California in 1962 and has only been seen occasionally since the. There is no vaccination.

Between 2009 and 2013, the National Enterovirus Surveillance System received 79 reports of this strain, the CDC says. It has been blamed for three deaths in the Philippines and Japan, while researchers said earlier this year that some children suffering from polio-like symptoms in California had tested positive for this strain.

This year, hospitals have reported a significant number of cases of this strain over the last two months. Hospitals in Chicago and Kansas City, Mo., reached out to the CDC in August after they saw a higher number of children with breathing problems. Cases were identified in six states by early September, at which point Schuchat said it was difficult to know “just how big” the outbreak was going to be.

The rare strain spreads when an infected person coughs, sneezes or touches some kind of surface that other people touch. Almost all of the confirmed cases so far this year involved children, who do not have the immunity that adults have developed, and children with asthma or preexisting breathing issues are at a particular risk.

However, while hospitals are able to test for enteroviruses, most are not able to check for a specific strain, which is why states are sending their samples to the CDC and waiting. The official numbers grew and grew and kept on growing as the CDC tested more and more samples.

Meanwhile, there have been six known cases where a patient with this enterovirus died. A Rhode Island child died of a staph infection associated with the enterovirus infection, but at the time it was unclear exactly how much of a role the enterovirus played. Authorities directly blamed the enterovirus for the death of a four-year-old in New Jersey late last month, while a child in Michigan died last week while battling the enterovirus infection.

The CDC also said Tuesday it has heard “informal reports” from hospitals and states suggesting that fewer enterovirus 68 infections were seen, but it does not know yet if there is any sort of national decrease occurring.

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