If it would just get cold and stay cold
I don't know what the weather has been like where you live but here in western New York State it has been a yo-yo. Many swings in temperature of at least 30 degrees F within 24 hours.
When young calves have issues with passive transfer of immunity combined with marginal nutrition these temperature swings seem to unerringly pick out the weakest calves for pneumonia.
In my personal experience nutrition seems to be a critical factor. I changed my feeding protocol from 16 ounces of powder to 30 ounces daily. Before the change I routinely treated 25 percent of the calves between birth and 2 months for pneumonia in the period from November to April.
After the increase to 30 ounces of powder per day that treatment rate dropped to 5 percent. The first year I thought maybe it was just a mild winter, maybe we didn't have too many stresses (like wild temperature swings). Then the next year and the next year the same low treatment rate. I became convinced that providing plenty of clean, wholesome milk/milk replacer can make a difference in the ability of calves to withstand the stresses of yo-yo weather.
If you have had a similar experience drop me a line; I would enjoy hearing from you.