Why the delta variant is more contagious and prevalent in younger populations

There is still much to learn about the delta variant of the virus that causes COVID-19. Here’s some of what we know now, including why it’s more contagious and how symptoms can differ.

Are younger people more susceptible to the delta variant?

The News & Observer reported that children are at lower risk of being hospitalized from COVID-19 but are at higher risk for spreading the more contagious delta variant. This is because the variant is more likely to spread among those who are unvaccinated — and no vaccine has been approved for children ages 5 to 12 in the United States.

“People who are now getting COVID-19 are largely younger and younger people,” said David Wohl, a professor of medicine who specializes in infectious diseases at the University of North Carolina School of Medicine.

Does the delta variant have different symptoms?

According to Wohl, younger people have “different patterns of symptoms” than older people, and men can have different patterns than women.

“It may just be a feature of who’s getting infected, rather than just what the virus is infecting,” Wohl said. “It’s hard to untangle.”

There is currently very little research on how delta infection symptoms differ from other variants, according to Wohl. But he said the biggest difference in how people present with symptoms is the amount of viral particles.

“The amount of virus that a person has when they get delta is much higher in their nose and throat, so that means more destruction caused by the virus, more of an immune response,” Wohl said.

How does this happen?

Viruses mutate over time to evade immune responses. The delta variant evolved to avoid the initial antibody response in the body, so fewer viral particles are being killed by the body, leaving more in the nose and throat.

“With delta, probably what’s happening is that it’s learned how to get around the initial antibody response. It’s been trained to do it by selection: the virus that happens to be able to do that is selected for and gets transmitted,” Wolf said. “So the initial immune response that protected us from the initial variants is now not really as effective against that.”

When people aren’t able to mount a robust immune response, they can get very sick with the delta variant, and they can also be incredibly infectious.

How can the delta variant be so contagious?

The delta variant is more contagious than the ancestral Wuhan variant of the virus. It is about 50% more contagious than the alpha variant, which was already 50% more contagious than the original coronavirus.

In addition to being spread among unvaccinated people, the higher transmission is also because having more viral particles also makes someone sick with the delta variant more infectious, according to Wohl. With more particles in the nose or throat, when people sneeze or cough, they’re putting more viral particles into the air.

“With many more copies of the virus in every cough or exhalation and for more days, that can lead to what we’re experiencing now, which is this hyper-transmission of the virus,” Wolf said.

Does being vaccinated and masking help protect against the delta variant?

According to Wohl, vaccinated people’s immune systems work better and generate a “broader, quicker response” against the delta variant.

“I think that’s why we’re seeing people who have been vaccinated not really getting sick from delta,” Wohl said.

Medical experts have warned of a potential wave of cases at the start of the school year due to young children not yet having an approved COVID-19 vaccine.

Vaccines are “preventing people from getting really sick and dying,” Wohl said. Vaccinated individuals who contract the delta variant often do not get extremely sick and only develop mild symptoms, according to Wohl.

But Wohl noted that even mild symptoms aren’t ideal — “who wants to not be around people for 10 days or maybe risk long-term COVID-19 and infecting someone else?”

Masking is also an effective barrier method that helps reduce the amount of virus in the air, Wohl said; inhaling fewer viral particles reduces chances of getting severely sick.

“The lower and lower that cloud of virus gets, the more dilute and less virus there is, the less it’s going to be infectious to someone else, and masks can help make that happen,” Wohl said.

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