Giving mice a special nasal spray vaccine called BPZE1 helps them stay healthier when they get a common lung virus, not by killing the virus, but by calming down their overactive immune response so they don’t lose as much weight.

Scientists gave mice a nasal spray vaccine called BPZE1 to help calm their allergic asthma symptoms—like wheezing and lung swelling—and it worked without making their allergy antibodies worse, while also switching their immune system from an allergy mode to a more protective mode.