The U.S. Food and Drug Administration said on Wednesday that preliminary results of additional testing of more dairy products has shown that pasteurization inactivates the bird flu virus.

The FDA released results from tests of products including sour cream and cottage cheese, after reporting last week that preliminary results from testing showed pasteurization kills the virus in milk and baby formula.

The U.S. Department of Agriculture (USDA) has confirmed bird flu in 36 dairy herds in nine states since late March. One Texas dairy worker tested positive for the virus.

The FDA said it has looked at 297 total retail samples of dairy products, and the results released on Wednesday represent tests of a group of 201 of those samples.

“It is a pretty good body of results,” Donald Prater, acting director of the FDA’s Center for Food Safety and Applied Nutrition, said on a call with reporters that also included officials from the U.S. Centers for Disease Control and Prevention (CDC) as well as the USDA.

“There are probably a few more products that we would look at just so that we make sure that we’ve got a good national sample,” Prater added.

CDC official Dr. Demetre Daskalakis said that 25 people had been tested so far for bird flu and that no additional positive cases had been found.

The agency tested a sample of the virus taken from the farm worker who was infected with H5N1 and found that all three commercially available antiviral flu treatments are effective against it. The worker’s only symptom was conjunctivitis, commonly known as pink eye. Currently approved antiviral drugs include Roche’s Tamiflu as well as a generic versions, GSK’s Relenza and BioCryst Pharmaceuticals’ Rapivab.

—Julie Steenhuysen, Tom Polansek and Caroline Humer, Reuters