The bird flu outbreak in U.S. dairy cows is prompting development of new, next-generation mRNA vaccines — akin to COVID-19 shots — that are being tested in both animals and people. Next month, the U.S. Agriculture Department is to begin testing a vaccine developed by University of Pennsylvania researchers by giving it to calves. The idea: If vaccinating cows protects dairy workers, that could mean fewer chances for the virus to jump into people and mutate in ways that could spur human-to-human spread. Meanwhile. the U.S. Department of Health and Human Services has been talking to manufacturers about possible mRNA flu vaccines for people that, if needed, could supplement millions of bird flu vaccine doses already in government hands. “If there’s a pandemic, there’s going to be a huge demand for vaccine,” said Richard Webby, a flu researcher at St. Jude Children’s Research Hospital in Memphis. “The more different (vaccine manufacturing) platforms that can respond to that, the better.” The bird flu virus has been spreading among more animal species in scores of countries since 2020. It was detected in U.S. dairy herds in March, although investigators think it may have been in cows since December. This week, the USDA announced it had been found in alpacas for the first time. At least three people — all workers at farms with infected cows — have been diagnosed with bird flu, although the illnesses were considered mild. But earlier versions of the same H5N1 flu virus have been highly lethal to humans in other parts of the world. Officials are taking steps to be prepared if the virus mutates in a way to make it more deadly or enables it to spread more easily from person to person. Traditionally, most flu vaccines are made via an egg-based manufacturing process that’s been used for more than 70 years. It involves injecting a candidate virus into fertilized chicken eggs, which are incubated for several days to allow the viruses to grow. Fluid is harvested from the eggs and is used as the basis for vaccines, with killed or weakened virus priming the body’s immune system. Rather than eggs — also vulnerable to bird flu-caused supply constraints — some flu vaccine is made in giant vats of cells. Officials say they already have two candidate vaccines for people that appear to be well-matched to the bird flu virus in U.S. dairy herds. The Centers for Disease Control and Prevention used the circulating bird flu virus as the seed strain for them. The government has hundreds of thousands of vaccine doses in pre-filled syringes and vials that likely could go out in a matter of weeks, if needed, federal health officials say. They also say they have bulk antigen that could generate nearly 10 million more doses that could be filled, finished and distributed in a matter of a few months. CSL Seqirus, which manufactures cell-based flu vaccine, this week announced that the government hired it to fill and finish about 4.8 million of those doses. The work could be done by late summer, U.S. health officials said this week. But the production lines for flu vaccines are already working on this fall’s seasonal shots — work that would have to be interrupted to produce millions more doses of bird flu vaccine. So the government […]