H7N9 spreads human-to-human: How scared should we be?

A women wears a face mask as the city's commuters protect themselves against the H7N9 bird flu virus in the downtown area of Shanghai on April 16, 2013. New evidence shows that the virus can be spread by human-to-human contact.

The most recent outbreak of avian flu, the strain H7N9, killed 22 people and infected 108 last April. The cases were only known to be spread through direct contact with birds until Thursday, when new research showed that the virus had jumped for the first time from one human to another.

It's the sort of development epidemiologists have feared, but it's still a far cry from a pandemic scenario. Is there reason to be alarmed?

Jason McDonald, a spokesman for CDC’s National Center for Immunizations and Respiratory Diseases, told GlobalPost that "there is no evidence to indicate that the H7N9 virus in China is spreading in a sustained, ongoing way at this time."

We also spoke with Dr. Neil Fishman, associate chief medical officer at the University of Pennsylvania Health System, who is optimistic that human-to-human contagion is limited. The following is a summary of our exchange with him:

New research indicates that the recent flu strain in China was spread by human-to-human contact. How important do you think this is?

Sporadic human-to-human transmission is expected and not a cause for alarm.

Scientists previously acknowledged that human-to-human contact was possible with H7N9. Is this a tipping point for the virus?

I wouldn’t call it a tipping point. This is expected. It would only be concerning if human-to-human transmission was widespread and sustained, and this has not been reported.

The prior bird flu outbreak, the H5N1 strain, has been smoldering for well over a decade. This is H7N9 and, on the optimistic side, there haven’t been that many cases.

What is the likelihood of an international spread of H7N9?

Still low given the relatively rare human-to-human transmission reported thus far. I am much more concerned about Yemen.

Widespread human-to-human transmission remains unlikely, particularly given the H5N1 experience.

How should the new evidence effect our response to future outbreaks?

I do not think it changes our approach. We must continue to remain vigilant for changes in virulence, disease manifestations and transmission patters, but this is consistent with our prior approach.

What do you think of the media response to the researchers’ findings?

Appropriately measured thus far. There is no cause for alarm at this time.

There’s still a lot to learn about this virus. I don’t believe that there is a saturation effect, that people are getting used to these outbreaks. I prefer to think of it as more of an educated response. There have been more outbreaks, the public has learned, the press has learned … we need to gather all of this information to see how an outbreak progresses.