On Tuesday, April 23, 2024, the U.S. Food and Drug Administration (FDA) announced that grocery store milk had tested positive for H5N1 fragments using a quantitative Polymerase Chain Reaction (qPCR) test. This test does not give information about the viability of the virus. A qPCR test can be positive even if the searched-for organism is dead. The FDA stated that egg inoculation tests were being conducted to help determine milk safety. Egg inoculation tests are considered the gold standard for determining if an infectious virus is present.
On Friday, April 26, 2024, the FDA announced that preliminary results from egg inoculation tests showed that pasteurization is effective at inactivating the virus, and no live, infectious virus was detected in the qPCR-positive samples. Additionally, the FDA stated, "Several samples of retail powdered infant formulas were tested, as well as powdered milk products marketed as toddler formula. All qPCR results of formula testing were negative, indicating no detection of viral fragments or virus in powdered formula products."
On Wednesday, May 1, 2024, the FDA announced that additional egg inoculation testing of more qPCR-positive samples of cottage cheese, sour cream, and fluid milk was negative indicating there was no live, infectious virus and that pasteurization continues to be effective.
The FDA is also continuing to test samples of pooled raw milk that has been routed to pasteurization and processing for commercial use. This will be used as a basis to characterize potential virus levels that pasteurization may encounter and will be used to inform studies to further validate pasteurization.
The FDA concluded that "in addition to preliminary results released late last week, these results reaffirm our assessment that the commercial milk supply is safe."
Source : umn.edu