Pharmaceutical companies are preparing to secure supplies of influenza drugs as more people in China contract bird flu.

The World Health Organization sees antiviral drugs such as Tamiflu, Inavir and Relenza as effective in containing the H7N9 strain that is reported in China if administered early enough.

Chugai Pharmaceutical Co. is in close touch with the Roche group of Switzerland, which manufactures Tamiflu and supplies Chugai with the drug for sale in Japan. Daiichi Sankyo Co., which manufactures Inavir, said the company is “prepared to boost production immediately if a major outbreak occurs.”

The Japanese unit of British drugmaker GlaxoSmithKline, which makes Relenza, said if health care institutions run out of the drug, the government’s stockpile will have to be tapped.

According to the health ministry, municipalities nationwide had enough Tamiflu and Relenza to treat 67.22 million people at the end of March. With the drugs’ shelf life spanning six to seven years, the amount “should be sufficient” to meet an uptick in domestic demand, a ministry official said.