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Is the Delta variant more transmissible outdoors?

Outdoor transmission of COVID-19 has been rare with previous strains of the virus. But as the hypercontagious Delta variant continues to drive up cases in some areas of the country, many have begun to wonder if this variant is more transmissible outdoors. As Labor Day approaches and many Americans plan to have outdoor gatherings, the question has become more urgent.


Dr. Diego Hijano, an infectious disease specialist at St. Jude Children's Research Hospital, explains what we know so far about Delta's transmissibility outdoors and how you can best protect yourself against it.

Video transcript

DIEGO HIJANO: I think there is no question, at this point, that Delta is much more transmissible than any other version of the virus that we have had here or any other part of the world that has been described. There's no question about it. It's not something that we can determine at this point. It's like, oh, the Delta outdoor is going to makes things more contentious. But certainly, it's more contagious period.

So if you, again, are in a situation outdoors with somebody, where you are in close proximity for a prolonged period of time, and the individual is coughing or not feeling well, then the risk is there probably more so than what it was before without a variance. The Delta variant definitely is more contagious, and the initial hypothesis, our thought is that we're seeing that individuals infected with this variant have a lot of virus in their noses. And that's what's driving the transmission, especially when you have an unvaccinated individual infected with this virus.

I think it's very important to note that the virus that you have in your nose needs a vehicle to go from one person to the other, and that's what we call the droplets, right? So when you sneeze, you cough, you talk. Those droplets are the ones that are carrying the virus from one person to the other.

That's why mask are so helpful, because they prevent from somebody coughing, throwing all those droplets into the air. But also, on the receiving end, someone with a mask that will get those droplets would be filtered by the mask. But definitely, the more virus you have in those droplets, the more likelihood that when those droplets get to somebody else, those viruses are able to infect the individual.

Outdoors, we always say, it's safer than indoors. But the nature of exposure is very important, you know? We have rules saying that indoor is riskier. But certainly, if you had a door in close proximity with someone that is coughing on your face, and you are not wearing a mask, then that outdoor rule isn't making any sense, right?

At least, at the end of the day, people need to have that sort of commonsense and say, if there is somebody coughing, even if it is outdoor, I should probably be distant and have my mask on. The most important thing you can do to protect yourself and others is get the vaccine. If you are 12 years of age and older, everyone getting the vaccine, it's the best way to move forward individually, and then as a group.