What makes some flu cases deadlier than others?

The 2017-2018 deadly flu outbreak is now as severe as the 2009 swine flu epidemic. The Centers for Disease Control and Prevention (CDC) estimates 63 children have so far died from complications to influenza. Health officials anticipate more outbreaks and deaths in the weeks to come.

So what makes some people more vulnerable than others? There are few key issues that seem to be arising in many of these cases:

1. Early detection and proper treatment

According to the CDC, the rapid flu test is only about 63 percent effective, so beware of a false negative and get treatment anyway. Anti-viral medicine Tamiflu is most potent in the first 48 hours - so don't wait. And don't skip the rest of the treatment even if you think you are better.

"Whether it's an antibiotic or Tamiflu, take the entire course because even though you might be feeling better, the disease itself might still be present so the illness still may be there," explained Dr. Areo Nazari, a pharmacist with CaryRx in Washington D.C. "The influenza may still be in your body, or the bacterial infection, whatever you are being treated for. So make sure and take the entire course as prescribed."

2. Bacterial or other infection developed during the flu

- Heather Holland, 38, of Texas, and Jenny Ching, 51, of Massachusetts, both developed pneumonia. It's one of the most common deadly complications of the flu.

- Savanna Jessie, 7, from Indiana, had strep throat and scarlet fever in addition to the flu.

- Eli Snooks, 5, of Georgia, developed an infection in his brain while with the flu. It wasn't found until after he was better and then got worse again.

"After treatment a patient may start feeling better and then another fever will arise," explained Nazari. "And so that is another possible presentation of a secondary infection. They will get that second fever. And it is important to know if you do get that second high-grade fever, go seek attention. Just because you saw your doctor a couple days ago and now you are getting that second infection does not mean you shouldn't show that just as much medical attention."

3. Other medical complications that may be beyond your control

- Kira Molina, 15, of Georgia, had liver failure in addition to the flu.

- Aaron Masterson, 12, also of Georgia, was fighting cystic fibrosis when he got the flu.

The bottom line: even though each case is unique and complicated, this year's flu strain is stronger than most and passive treatment may not be enough. To really protect yourself, seek early detection and treatment, know what is normal and what is not - such as additional symptoms or a returning fever, and get the flu shot. Reducing symptoms by even 10 to 20 percent could be the amount needed to save your life, doctors say. Dr. Nazari also advices people to get the pneumococcal vaccine to protect against pneumonia.