House Republicans sounded the alarm Friday over an avian flu threat that’s escalating in China, saying it underscores the need to finish and vet an overdue plan for responding to pandemic flu at home.

The H7N9 avian influenza virus mainly affects people who’ve been exposed to live poultry. It’s infected nearly 1,000 people in Asia and had a 40-percent fatality rate since its discovery in 2013, though the latest spurt of cases has been worse than previous ones, according to the World…