A team from the University of Massachusetts Amherst and Johns Hopkins in Baltimore has created a new algorithm that signals when flu transmission is rising and helps public health officials and hospitals declare the start of flu season.
"You don't want to declare flu season too early," said Nicholas Reich from the University of Massachusetts Amherst, because once flu season starts, hospitals begin taking extra precautions with personal protective equipment and reduced visitor access, among other actions. "For hospitals, there is a strong incentive to define a really clear period as flu season. It does not start the moment you see the first case in the fall. If you begin the full response too early, you set yourself up for a long slog and too much effort will be spent on too few cases. You want to be as effective and efficient as possible in your preparations and response."
The algorithm, called Above Local Elevated Respiratory Illness Threshold, or ALERT, will help hospitals and other healthcare professionals declare the start of flu season in their area. It uses routinely collected data, like weekly counts of lab-confirmed flu cases, and hospital epidemiologists upload historical flu data ALERT uses for comparison.
"The algorithm can help you to estimate the threshold at which you should start to think about declaring that flu season has started," said Mr. Reich. "And, very importantly, your staff can have a sense that it will not go on forever, but that for the next 11 or 12 weeks, for example, you'll be taking the extra precautions."
ALERT is open-source and publicly available.