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DES MOINES, Iowa — It’s easy to assume that if one person in your household develops COVID-19, then everyone will, but that is not always the case.

A recent report from the CDC showed chances of transmission in close household settings is about 53%, leaving room for some to not develop the virus. A physician with MercyOne, Dr. Joseph McGargill explained that there are many reasons behind this.

“If someone has the stomach flu or influenza, not everyone gets sick. So we see that with COVID as well too. So, we have let’s say five people and two people don’t have symptoms, three people have COVID symptoms. Typically the reason for that is, is it’s multifactorial, there’s lots of reasons for it,” said McGargill.

The main factors are: 

  • Known or unknown pre-exposure: There is a chance that someone had COVID beforehand and not known. This means that their body has antibodies against the current infection in the household, making it easier to not catch it.
  • Current exposure: Although in close contact. There is also a possibility that someone didn’t get a large enough antigen or large enough exposure to the virus, that they don’t actually get sick at all. 
  • Genetics: some people may have COVID, but genetically respond better to the virus, meaning they may have a positive test but are not showing any symptoms. 

“That’s why it seems like certain illnesses like COVID will really be hard on certain families. So you’ll hear of a family that goes to a family reunion and their…their whole family has it severely,” said McGargill. “You know, a lot of people die. A lot of people are just very severely impacted by COVID. And then you’ll have certain families that get it and it’s just a cold and the sniffles, and that’s it. So there’s definitely some genetic factors.”

Dr. McGargill said although this does happen, it is important to act like you could end up sick if someone close to you, like a family member tests positive. COVID is most contagious two days before someone shows symptoms and three days after.