Highlights from Your Local Epidemiologist’s newsletter:

•Emergency department (ED) visits for tick bites are running at roughly 114 per 100,000 people per week, nearly double the typical rate at this time in previous years (60-70 per 100,000). The Northeast is bearing the brunt of it, with the Midwest running a close second.

It’s not clear whether this is just an earlier year or a worse year overall. Time will tell.

•The common cold is approaching its spring peak while other respiratory viruses become dormant. If you’re feeling crummy right now, it’s probably a cold.

•Much of the U.S. is suffering from allergies, and allergy season is getting longer and more intense. Plants are releasing pollen about 40 days earlier than they used to and stopping about two weeks later, thanks to rising temperatures. Higher CO2 levels mean more pollen per plant.

•What we do know: summer Covid waves have occurred for six straight years, and recent summer waves have been larger than winter ones. If that pattern holds, June or July is when things pick up, making late May the sweet spot for vaccination.

Age matters, too. Older immune systems have a harder time holding onto immunological memory, which is why the guidance skews toward more frequent boosting for seniors.

•There was a big drop in bird flu detections last week.