From Beijing to Hong Kong, Tracking H7N9's Spread

The H7N9 virus is the newest strain of avian influenza to infect humans. New cases of the infection have surged in recent weeks after a temporary slowdown in 2013. The Chinese government has restricted live poultry sales and quarantined farms in cities with the most H7N9 infections.

Graphic Updated Jan. 27, 2014

New Infections Surge as Winter Sets In

Through June 11, 132 cases of H7N9, including 39 deaths, have been confirmed by the World Health Organization. Investigations into the cause are ongoing and there is no evidence of sustained person-to-person spread of the virus. Most of the infections have occurred in middle-aged or older men, according to WHO reports.

Laboratory-confirmed cases of A(H7N9) in humans,
by reported date of illness onset or death1

Cumulative figures
Non-fatal cases
Total deaths
Hong Kong

Comparing Recent Flu
Outbreaks to H7N9

A(H7N9) is a novel influenza strain that shares genes of three previously recognized avian flu viruses. The H7 subtype of influenza viruses were first detected in people in 1996, and rare, sporadic human infections have since occurred in the U.S., the Netherlands, Italy, Canada, Mexico and the U.K.

The H7N9 now circulating in China hadn't been reported in people before the confirmation of infections dating back to February 2013. The virus is unrelated to the H5N1 strain that was first detected in China in 1996 and has since killed hundreds globally.

of Virus
H1N1 Swine Flu
(2009 Pandemic)
H5N1 Bird Flu
(Ongoing Strain)
H7N9 Bird Flu
(Ongoing Strain)
How does
it spread?
From person to person From infected birds,
person to person is rare
Currently unknown, possibly through contact with birds
Reported cases worldwide As many as 89 million 649 cases 132 cases
as of June 11
Reported deaths At least 18,449,
possibly up to 575,000
385 deaths 39 deaths,
as of June 11
About 0.02-0.9% About 60% About 25%,
based on limited data
Symptoms Fever, cough, headache, body aches, sore throat, runny nose High fever, cough, sore throat, muscle aches Severe pneumonia, fever, cough, shortness of breath
Vaccine availability Readily available Vaccines developed, but not ready for widespread use No vaccine available,
currently in development

1 – Case information reflects World Health Organization information and may not represent total number of human infections or deaths. Figures after April 15 reflect changes to how the WHO reports prior infections and deaths. Flu cases and deaths are based on laboratory confirmation and often thought to significantly under-represent actual figures.

Sources: World Health Organization, U.S. Centers for Disease Control and Prevention, British Medical Journal 2009;393:b5213

Graphic: David Ingold & Chloe Whiteaker / BLOOMBERG VISUAL DATA