Merck chicken bronchitis vaccine approved for use in China

BEIJING - Merck said its vaccine against bronchitis in chickens has been approved by the Chinese agriculture ministry for use in the world's largest chicken-rearing country, which is home to over 5 billion birds.

Any chicks that hatch today can be vaccinated from Thursday, with the live vaccine formulation suitable for chickens aged 1 day and above, the U.S. company said on Wednesday.

• The vaccine targets infectious chicken bronchitis strain 4-91, a highly contagious chicken coronavirus first identified in Britain in the early 1990s.

• Side effects of chicken bronchitis typically include reduced egg production and coughing, according to the US National Institutes of Health research institute.

• Chicken bronchitis has a "high mutation rate and rapid transmission," Zhang Guozhong, a professor at China Agricultural University, said in the statement, warning of "severe and complex" epidemic risks across flocks.

(Reporting by Joe Cash;Editing by Elaine Hardcastle)

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This story was originally published May 27, 2026 at 12:11 AM.