The Washington Post solved some of the mysteries surrounding why the Centers for Disease Control and Prevention suddenly changed its mask guidance without providing any explanations. The CDC had revealed that the COVID-19 delta variant was more dangerous than previously believed and that it is more contagious.According to the document, there was evidence that people who were vaccinated against the delta variant of the virus shed just as much as those who weren't. The Post reported on Friday afternoon that a CDC study had shown that vaccinated people were just as likely to contract the virus as those who weren't vaccinated. The study revealed that nearly three quarters of the outbreak in Provincetown (Massachusetts) that started with July 4 celebrations had been vaccinated.AdvertisementThe CDC director stated that this finding was alarming and led to the updated recommendation for CDC's mask.AdvertisementAdvertisementSlate interviewed Dr. Larry Corey from the Fred Hutchinson Cancer Research Center to understand how alarming this news is. This interview has been edited and condensed for clarity.Slate: This news is so surprising!Larry Corey: It was a teaching moment. It was a moment of learning that density is the fuel for the virus. Potentially, density can be a threat to the human. Indoor crowding, particularly during celebrations where you are speaking or drinking, is still a high-risk situation. There is a limit to what you can do.What should people do to understand this news?AdvertisementOkay, there is an outbreak. This reminds us of the fact that vaccines can be overwhelmed, regardless how effective they may be. There are limitations. It is still rare. If we examine the data from the United States, we see that 99 percent of hospitalizations occurred in people who were not vaccinated in the month when delta was dominant.We have a few hospitalizations where people were vaccinated. They did well, however, from a hospitalization perspective. No one was hurt. It was a kind of teaching moment. I believe that the vaccines were not invulnerable. That delta is a formidable variant. Also, high-risk indoor exposures can overwhelm vaccination. It appears that most people received their second dose of vaccine within 100 days.AdvertisementIn terms of what vaccinated persons should do to change their behavior, you are primarily advising them to avoid indoor crowds.Avoid indoor events that have high density. Personaly, I'll say that when Im going to the grocery or indoor shopping malls, my mask is on.What would you tell people who care less about their safety but more about giving COVID to others?Vaccination can prevent the spread of asymptomatic infections. We don't know how often that happens, or how often you get infected. Although we have a few studies in the field that might help us get a handle on this, it is still a few months away. Unfortunately, we don't have enough data to quantify that. Vaccines are intended to decrease the severity of disease as well as the medical complications. At 94 percent, the vaccines against the first variant prevented you from becoming ill. With delta, this may drop to the 80s or 85 percent. However, that still leaves 98 percent against death and hospitalization. That is the goal. This was the main goal of vaccination.AdvertisementAdvertisementDo you think you might have other big, important questions?Also, I don't think that this outbreak means anything about booster shots at this time. We wouldn't know if it would affect any of this. It would it be more effective in protecting you against nasal colonization? At the moment, we don't know. This outbreak does not seem to reflect that.What should people do right now to be worried about?I don't believe the sky is falling. It is a moment to realize that even if you are vaccinated, it is important to be cautious. Vaccines work. They work. The data from the United States continues to prove that vaccines do work. However, there is no guarantee that anything will work. Transmission can be achieved by bringing together a large number of people in an indoor space.
