Covid-19 is still surging around much of the world. And though experts believe influenza rates might be lower than usual, we’ll still collectively be facing multiple contagious respiratory illnesses at the same time. A “twindemic,” if you will.  

Don’t fall victim to the mistruths. Here are five big misconceptions people have about the illnesses, which everyone needs to unlearn as we head into flu season and a possible second wave of Covid-19:

Myth: The flu won’t be a problem because we’re wearing masks.

Doctors “are hoping — but not betting on — a lighter influenza season this year as people practice physical distancing, mask wearing and better hand hygiene,” said Dr. Timothy Laird, interim chief medical officer of Health First Medical Group.

Sometimes you can do just about everything right — mask up, maintain social distance, wash your hands — and still catch a virus. Which is why layering preventive measures is so important. People can get the flu by touching surfaces or objects that have been contaminated with flu viruses (which is also true with Covid-19, although that isn’t the primary mode of transmission).

“Everything we’re doing reduces risk,” said Dr. Aaron Milstone, an epidemiologist and professor of paediatrics at Johns Hopkins Medicine. “It doesn’t make risk zero.”

Myth: The flu vaccine could make you sick, weak or more vulnerable to Covid-19.

The persistent claim that the flu vaccine can give you the flu just is not true, experts say. However, you could develop a flulike reaction to the vaccine (including muscle aches and fever) as your body produces antibodies.

“You may get a sore arm, maybe even feel a bit achy or have a low grade fever or scratchy throat,” Laird said. “But that’s not an illness, that is a side effect experienced by a small number of people with nearly any vaccination.” 

There are a few other possibilities for why you might get sick after vaccination: You could catch the flu in the two-week window between getting your hab and when it takes effect. Or you could get sick if you’re exposed to a flu virus that isn’t a good match with those used in this year’s vaccine. 

But the vaccine itself will not give you an illness. That’s a key misconception to clear up now for anyone who is reluctant to get vaccinated over concerns the jab will make them sick and weaken their immune system amid a pandemic, making them more vulnerable to Covid-19. It won’t. 

On the other hand, it is possible to get both Covid-19 and the flu at the same time, which could be “catastrophic” to the immune system, some experts warn. 

Myth: The flu vaccine could “mess” with a Covid-19 vaccine.

“We give vaccines together all the time,” Milstone explained. “The only time we sometimes worry about separating vaccines with a little bit of time is when we give a live viral vaccine.”

For example, doctors might space out other vaccinations around the measles, mumps, and rubella vaccine, so patients get the full immune response. But all the injectable flu vaccines currently available right now are not live vaccines, Milstone said, so it shouldn’t be a concern. 

Myth: Covid-19 and the flu are essentially the same. 

It’s not true in terms of the effect on the body; it’s not true in terms of how long people are contagious or how contagious the various viruses are; and it’s not even true in terms of who tends to get really sick. 

“There’s a difference epidemiologically,” Milstone said.

It’s also not true for death counts. Distinguishing the difference has implications for everything ― from how doctors might watch for more serious developments to how long someone needs to quarantine and how people who’ve come into contact with a sick individual should behave.

Which brings us to … 

Myth: If I were to get sick, I would manage Covid-19 and the flu in the same way. 

There is definitely significant overlap in the symptoms of Covid-19 and influenza, like fever, chills, fatigue and cough. They are also both highly contagious respiratory viruses. So in some ways, yes, a person who becomes ill with the flu might behave pretty much the same as a person who becomes ill with Covid-19. 

“There are a few common principles to keep in mind. First, you are contagious,” Laird said. “Protect others. Wear a mask if around them. Everyone should practice excellent hand hygiene, and you should isolate yourself as much as possible. Secondly, hydrate and rest.”

But knowing which particular virus you have will likely change how you proceed beyond that. Researchers are still grappling with exactly how long someone can spread Covid-19, but they believe the period of contagiousness is longer than with the flu. With the flu, people are generally cleared to head back into the world once they’ve been fever-free for 24 hours; with Covid-19 it’s at least 10 days since symptoms appearedand the individual has been fever-free for at least 24 hours. 

That’s one reason why doctors, like Milstone, are advocating that people who develop symptoms be particularly diligent about getting tested this season.

“I think most people are going to need to get a test result to know: When can I safely return to work, school, daycare, etcetera,” Milstone said. 

Experts are still learning about Covid-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.