CDC urges doctors to speed subtyping of patients hospitalized with flu to better track H5N1 infections

The CDC is calling on doctors and hospitals to perform subtyping on all hospitalized patients who test positive for influenza A, ideally within 24 hours of admission.

(CNN) — The US Centers for Disease Control and Prevention is urging hospitals to accelerate advanced testing of people they suspect may have bird flu.

Its alert to doctors and hospitals follows a few rare but mysterious bird flu cases in the US – including, most recently, a child in San Francisco confirmed to have had H5N1 influenza – that do not appear to be linked to exposure to animals. Another person in Missouri also tested positive for bird flu last year without any known exposure to animals.

Because public health agencies have learned that these patients had bird flu days or weeks after the person became ill, it has hampered efforts to find out how they were exposed and make sure they don’t pass their infections to others.

One of the ways the CDC has stepped up its surveillance of H5N1 infections in people is by asking state public health laboratories to perform additional testing on all patient samples that test positive for influenza A. This testing tells doctors specifically what subtype of flu – such as H1N1 or H3N2 – a person has.

The CDC is calling on doctors and hospitals to perform subtyping on all hospitalized patients who test positive for influenza A, ideally within 24 hours of admission.

“It’s the subtyping that takes us from knowing that a virus is in the general bucket of ‘influenza A’ to knowing more specifically whether it’s a garden-variety seasonal version of influenza A or, more rarely, a novel version of influenza A like H5N1,” CDC Principal Deputy Director Dr. Nirav Shah said.

Although there is no human-to-human transmission of bird flu in the US and the risk to the general public remains low, there’s a lot of H5N1 virus circulating in animals, as well as usual seasonal flu activity picking up in people, so Shah said it was important to switch to a system that identified potential bird flu cases more quickly.

“The system right now tells us what has already happened. What we need is to shift to a system that tells us what’s happening in the moment. That is what we are doing today,” Shah said.

A more streamlined system would improve the protection of health care workers and contacts of bird flu patients, as well as helping investigators interview patients while their memories of potential exposures were still fresh. It would also help doctors treat patients with Tamiflu and other antiviral drugs when they are most effective, early in the infection.

Additionally, Dr. Demetre Daskalakis, director of the CDC’s National Center for Immunization and Respiratory Diseases, said it would help public health officials identify any change in the frequency of bird flu infections in case the virus began to transmit more efficiently in people.

“One of the motivators of accelerating testing so that we are, again, able to faster see difference between signal and noise, given that the volume of hospitalizations is going up as expected in a rather routine flu season,” Daskalakis said.

About 100,000 Americans have been hospitalized with type-A flu this season, and Shah said officials expect to see another 100,000 hospitalized before its end.

The increased urgency around testing comes just as key leaders at the major federal agencies involved in the bird flu response are preparing to hand off their efforts to the incoming Trump administration and appointed staff.

The US Department of Health and Human Services released a playbook this week “that future administrations can use to continue to protect the nation” that it provided the incoming administration, along with summaries of its investments.

One of the newest investments, announced Thursday, was $211 million to support the development and long-term manufacturing capability of an RNA-based vaccine platform technology to combat evolving 21st century biothreats, including bird flu.

Dr. Eric Deeble, who is leading the bird flu response at the US Department of Agriculture, said there are about 300 people dedicated to the response “across the agency.”

Ensuring a smooth transition between administrations was one of the agency’s “foremost priorities,” he said. Members of the agency have met with members of the Trump administration about bird flu several times, including a tabletop exercise at the White House on Wednesday.

Career staff will remain in place to help with the transition, and Deeble says he has “full confidence they will continue to do exceptional work.”

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