The estimates have changed over time, but the Centers for Disease Control and Prevention is now saying that some 40 percent of COVID-infected people will be asymptomatic or only mildly symptomatic. This is up from a CDC estimate of 25 percent back in April.

It's all the more reason to remain vigilant and socially distant, because not only is the coronavirus highly unpredictable in who it strikes down with extreme force, it's highly capricious in passing between people who have no idea they are even sick.

This latest estimate is cause for concern, certainly, but UCSF infectious disease specialist Peter Chin-Hong suggests that it could be cause for some optimism as well. He and multiple experts have recently been discussing the asymptomatic stats as a sign of the body's T-cell response.

"Usually people with asymptomatic infection are not... identified because there is no motivation to go get tested," Chin-Hong tells KRON4. But the sheer amount of testing is showing experts a better picture of how frequently the virus infects people without many health impacts at all — a fact that has some experts surmising that for some people's immune systems, this isn't a new virus at all, but it's triggering a normal and quick response based on other coronaviruses the body has encountered.

"It’s comforting to know that at least not everybody who is asymptomatic will progress on this train to bad things and there’s many people with asymptomatic disease who may kind of be the chosen ones or protected and may not get sick," Chin-Hong says, "but the problem is we don’t know who those people are that’s why we need to all maintain safety right now."

From the beginning, though, experts have warned that the term "asymptomatic" is misleading — for many people testing positive, they may simply be pre-symptomatic, and the data about their later symptoms does not get recorded, or they may be mildly symptomatic and just not recognizing the symptoms at the time for whatever reason.

And here's another alarming statistic to tell your overly cavalier friends under 40: A UCSF study recently found that 1 out of 3 young adults could be susceptible to a severe COVID case requiring hospitalization.

Anyway, wear your mask! And not just a neck gaiter!

Related: Young Adults Now Represent Nearly Half Of All COVID Cases In SF, Over One-Third Of Cases In California

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