Five takeaways on the science behind the CDC's latest mask guidance
With surges in Covid-19 cases driven by the Delta variant, most Americans are now being advised to wear masks indoors -- regardless of vaccination — by the US Centers for Disease Control and Prevention.
Since CDC guidelines updated Tuesday, we have learned more about the science that motivated these changes, both from a leaked agency document and a study published Friday by the agency. The new research reinforces the ongoing need for everyone who can get vaccinated to get vaccinated. Here are five key takeaways:Delta is super transmissibleWe knew Delta was spreading fast. In the United States and around the world, it swiftly overtook another variant, Alpha, that was already more transmissible than earlier strains.Read MoreNew research from Helix, a company whose Covid-19 tests have helped track a number of variants, shows how quickly that happened: Alpha made up 67% of cases in mid-May. Ten weeks later, it was down to just 2.3% -- replaced by Delta, estimated around 90% of cases.What's different about the Delta variant? Here's what's known"It's one of the most transmissible viruses we know about. Measles, chickenpox, this -- they're all up there," Walensky told CNN Thursday.In terms of how quickly they spread, early strains of the coronavirus were similar to the common cold, according to an internal CDC document. Left unchecked, an infected person may have transmitted the virus to two or three people, on average, early in the outbreak. But now, with Delta, that number could be five to nine.This may be partly explained by Delta's ability to"replicate faster and lead to higher viral loads earlier in infection compared to other variants," according to the preprint study from Helix.The CDC document also notes that Delta is"likely more severe" than what came before it.Breakthrough infections may be contagious, but spread is driven by the unvaccinatedPrior to Delta, even if you developed a breakthrough infection, you'd likely have less virus in your airways. Thus, you might be less likely to infect someone else if you were vaccinated.Experts say that vaccination still makes it less likely that you'll catch Covid-19 in the first place -- but for those who do, new data suggests that Delta causes similar viral loads in both vaccinated and unvaccinated people.The data is based on an outbreak investigation in Massachusetts in which nearly three-quarters of infected people had been fully vaccinated. Of them, 8 in 10 developed symptoms, but only a few were hospitalized and none died.Analysis: CDC fails to publish data needed to judge risk of breakthrough infection"The idea that someone could still test positive and still develop enough virus in their nose and mouth to transmit is really what this data is showing," explains CNN's Chief Medical Correspondent Dr. Sanjay Gupta.The finding that the Delta variant resulted in similar viral loads"was a pivotal discovery leading to CDC's updated mask recommendation," Walensky said Friday. But viral load by itself may not be a definitive measure of contagiousness. For example, the immune systems of vaccinated people includes a number of moving parts that might impact how much they are able to spread it.Walensky said that ongoing outbreak investigations will help uncover more about what happens when these breakthrough infections do occur."We are now continuing to follow those clusters to understand the impact of forward transmission of those vaccinated people," she said earlier this week."But again, I want to reiterate, we believe the vast majority of transmission is occurring in unvaccinated people and through unvaccinated people."Vaccination is the best tool against Delta The effectiveness of Covid-19 vaccines is a spectrum: As you move from asymptomatic infection to hospitalization and death, effectiveness eventually reaches over 90%. Pfizer data suggest third dose of Covid-19 vaccine 'strongly' boosts protection against Delta variantCDC documents estimate that vaccines reduce the risk of infection three-fold, and the risk of severe disease or death 10-fold or greater."Getting vaccinated continues to prevent severe illness, hospitalization and death -- even with Delta," Walensky said this week. CNN's Gupta pointed out we've seen this trend reflected in the Covid-19 numbers on a national level."Last year when we would talk about a rise or surge in cases, almost predictably, you would see a certain percentage of hospitalizations that would follow thereafter, and a certain percentage of people who would die a few weeks after that," he said.But the country has not yet seen the same magnitude of tandem hospitalizations and deaths. Experts say this metric is key when discussing if and when people might be advised to get a booster shot -- but as for now, the vaccines continue to hold up in this regard.Masks are another necessary toolMore than 8 in 10 Americans live in a county with enough Covid-19 transmission for CDC to recommend people mask up indoors, even if they're vaccinated.These fully vaccinated Americans got breakthrough infections. They say it could have been worse without being vaccinatedThe move has already prompted a number of places, like businesses and school districts, to update their mask policies.It's not just Delta's prevalence and contagiousness that motivated the CDC to update its guidance, but also lower uptake of Covid-19 vaccine than hoped."Given higher transmissibility and current vaccine coverage, universal masking is essential to reduce transmission of the Delta variant," internal CDC documents say.Similarly, research published Friday in Nature Scientific Reports maintains that vaccination alone won't stop the rise of new variants. The authors also warn of an"evolutionary arms race" where the virus may be allowed to spread and evolve among vaccinated people, potentially outsmarting our immunity in the future.However, experts say we can bring the virus under control by layering strategies on top of vaccination -- masks especially, but also measures like distancing and testing."The measures we need to get this under control -- they're extreme. The measures you need are extreme," Walensky told CNN.As more people get vaccinated, we'll see more breakthrough infectionsBreakthrough infections were always expected. Simply put, no vaccine is 100% effective.It also makes sense that, as more and more people get vaccinated, you'll see more breakthrough infections.In April, mathematician and epidemiologist Adam Kucharski wrote on Twitter that these"patterns in highly vaccinated populations don't always do what you may assume."As illustrated in CDC documents, a mathematical formula known as Bayes' theorem can give us some rough estimates: Get CNN Health's weekly newsletter Sign up here to get The Results Are In with Dr. Sanjay Gupta every Tuesday from the CNN Health team.
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The most trusted name in mis-information. good The Frankenstein Virus . Observe that the increase in cases started along our southern border. Did illegal migrants bring the delta variant? Investigate!!!!! If you cover your face your’e simple, no ifs or buts, you’re as thick as they come. The shot is fake!! Covid is fake!! Its really the FLU!!. Test are fake!!…… getting a shot of God knows what to Allow people to be out and about open businesses and schools has gotten proven what a BIG HOAX it all has been… wake up people
COVID-19 live updates: New CDC brief says vaccines may be less effective against delta variantJapan’s government will put in place a coronavirus state of emergency covering three of Tokyo’s neighboring prefectures and Osaka on Monday. Today, Japan has 9 deaths and US has 382 deaths. Uh…🤔 One question. How many hours are until Monday? About time we need the same thing because of the GOP Hesitancy Policy. The GOP open the door for China to win the economic fight by shutting down the economy with COVID again.
CDC shares 'pivotal discovery' on Covid-19 breakthrough infections that led to new mask guidanceA new study shows the Delta Covid-19 variant produced similar amounts of virus in vaccinated and unvaccinated people if they get infected -- illustrating a key motivation behind the federal guidance that now recommends most fully vaccinated Americans wear masks indoors. You’ve lost the plot! Fear mongering and lies, damn I feel sorry for my American friends Well, this is a disturbing turn of events. expect to endure the war. you have my brother HUSHPUPPI. it is the war which started. I will be in New York to do your skin
Most COVID-19 cases in Massachusetts outbreak among vaccinated, says CDCThree quarters of people infected with COVID-19 at public events in a Massachusetts town were fully vaccinated, a study by the U.S. Centers for Disease Control and Prevention (CDC) showed. 주님을 섬기는 것은 마음에서부터 지시받는 것입니다 OurEternalHome Why is that? Is that because the unvaccinated are not going anywhere or because the vaccine does not help and make people more susceptible to the disease? Because most of MA is vaccinated and they can carry Delta
CDC & WHO: People Who've Had COVID Should Still Get The VaccineCDC & WHO: People Who've Had COVID Should Still Get The Vaccine “If you're eligible to get the vaccine, GET. THE. VACCINE.”
COVID-19 live updates: Delta leaves vaccinated, unvaccinated with similarly high viral loads, CDC saysA pandemic of the novel coronavirus has now infected more than 195 million people worldwide and killed over 4.1 million of them. Blame the unvaccinated for the continued virus uptick. The trump virus is like trump it just won't go away. If it’s soooo alarming why hasn’t POTUS closed the borders? I’ll tell you why the news on delta covid is a political distraction so you don’t have to report all the things being ruined by Biden! Load of crap. If you want the vaccine get it if not don’t and wear a mask. Simple -
CDC director tells Bret Baier government 'looking into' potential COVID-19 vaccine mandateCDC Director Rochelle Walensky was pressed Friday on 'Special Report' as to whether she supports or foresees a federal vaccine mandate, as the Biden administration publicly laments continued vaccine hesitancy in parts of the country. Welcome to the service The world went all wrong .. all because of greed and hate.. its sad to watch To hell with that!