The Flu Is Here, And It’s Early

Sasha-Ann Simons (0:11)

—Music— Hey Chicago, I'm Sasha-Ann Simons, and this is In the Loop.

—Music— Be sure to listen all the way through the podcast for a breakdown of the day's top local stories. But first, flu season is here, and if you hadn't noticed, it arrived a little earlier than usual. Across the Chicago area, flu cases and hospitalizations are already climbing fast. And while overall numbers are still relatively low, influenza test positivity is at 2.1 percent. That's higher than we typically see this time of year. So what does all this mean for your household, your workplace, and those holiday plans that you've started putting together? In this episode of the pod, I will ask an expert what's driving the increase, who should be especially concerned, and the steps you can take to protect yourself and your family. I was joined by Dr. Mia Taormina, infectious disease specialist with Duly Health and Care.

It's October, so I started by asking the doctor, is this normal? Here's Dr. Taormina.

Mia Taormina (1:15)

We are seeing numbers come up earlier than I would like. I always tell my medical students to be aware when we start seeing flu cases in September or in October. That sometimes begets a really bad December, January to come.

Oftentimes, we don't see a single case of flu until much colder months, but we've had shifts in the environment and we've had changes in global temperatures, changes in dynamic travel, and here we are with a flu season that's starting earlier than we would like. So first and foremost, if we haven't been vaccinated for influenza yet, it is time right now. That 2.1% positivity rate amongst cultures and studies that are taken in the Chicagoland area is much higher as of the end of October than we've seen in years past. We've had similar years, but this year is starting to look like it might not be a favorable one.

Sasha-Ann Simons (2:11)

Tell me more about some factors that you think may be causing this early spike in flu cases.

Mia Taormina (2:17)

So I think it's a combination of temperature and environmental changes, just being favorable for the spread of influenza. We've had year after year, winters that aren't as cold as we've had them in the past. And when we have colder winters and we have colder fall and autumn seasons, it drives a few things. Certainly viruses don't thrive quite as well, but also we're not necessarily out and about and being more interactive with our friends and socially, and there's those factors as well. So it's a lot more kind of being close together and a lot more temperatures not leading to suppressing this virus as much as we can see in some really cold years. So it's kind of the perfect storm.

Sasha-Ann Simons (3:05)

And so we're clear, when is the typical flu season?

Mia Taormina (3:08)

So usually influenza season peaks in December and January. We sometimes get another bump later on in February, and that's when I see more influenza B cases. Right now, it is dominantly, dominantly influenza A. There are a few B cases popping in, and of the strains of influenza A, it's the H1N1 strain that we are seeing most commonly coming back positive when patients do have influenza right now.

Sasha-Ann Simons (3:33)

Yeah, tell us more about the strains, because there are different strains of the flu. Explain the difference between them as well.

Mia Taormina (3:40)

So, influenza A is, so each vaccine, this year, we have a trivalent vaccine, which means the flu shot is going to cover three of the most common circulating strains of influenza.

For years, we had four strains covered, a quadrivalent vaccine. We've removed one of the influenza B strains, the Yamagata strain, because we just haven't seen that circulating in the last several years. So, the last few years, we've had just three strains in our flu vaccines. So, that's going to be the H1N1 influenza strain, influenza A strain, the H3N2 influenza A strain. And influenza A is what can shift and drift and cause more pandemic influenza if there was ever a pandemic of influenza. Influenza B is less likely to cause pandemics. It can cause some epidemics, meaning local spread of a pocket infection in a particular area, but it doesn't mutate quite like the influenza A strains do. So right now, our vaccine covers all three.

Those are the dominant circulating viruses right now. It seems like the flu shot will be a pretty darn good match this year for what's going around. And of course, those aged 65 and older should get a high dose vaccine which will have more antigen in it for more durable protection.