david eisenman say at least 50% of the community needs to use the tracing app for it to be effective.>> doctors are sounding the alarm on a hidden crisis. focused on fighting the coronavirus, many hospitals have banned nonessential surgeries and some serious medical procedures have been postponed. some doctors say down the line more people could die from not getting surgeries they need than from covid-19. >> it's just this constant head pressure, so it's always on my mind. it's just the fear of the unknown. >> she's having brain surgery. this is not elective. nobody elects to have brain surgery, right. >> the gray zone are urgent procedures which should be done within one or two weeks and those are not being done. >> one san francisco hospital went from doing 70 operations per day to just 8. >> wow, huge drop there. >>> and coming up, a big surprise at a dog shelter in florida, plus a new way to get yourself a cold beer coming up next. ♪ you make my heart sing ♪ but i wanna know for ♪ sure yeah we all wanna know, honey... so... blue. blue means boy. blue means boy! it's a boy! if you

david eisenman.tudy out today suggests that people may be most infectious before theyhow ey do have symptoms.as what is it going to take to change that process, and how concerning is this for you? >> well, the study confirms what we've believed for a while, which is that people are contagious approximately 2 1/2 days before they develop symptoms. so it really reinforces the importance of social distancing. because people can spread the disease when they are asymptomatic. it also reinforces the value of the recent new york restriction or law that requires wearing a face covering in public. because you can spread it during those 2 1/2 days before you're sick just by talking and exhaling. it also gets to the point that we absolutely must have much more testing than we do. that everybody who wants a test needs to be able to get a test, like president trump offered on march 6th. anybody who feels mild symptoms should be able to get a test. anyby who isxp someboen thoey may not feel sick at the moment, wan

david eisenman. as always, thank you for joining us this morning.reopening the country, the cdc director is warning that the second wave of covid-19 next winter could be even worse when coupled with the normal flu season. dr. deborah birx from the white house task force says we will have better ways to target the virus in the fall and better testing by then, but how confident are you about our preparedness for the second wave? >> yes, so flu plus covid-19 at the same time, that's a one-two punch. it's going to be very hard for doctors and patients to tell them apart. it's going to make it incredibly important that we have tests for everybody. everybody's going to need both a flu test and a covid-19 test. so what this comes down to once again is the issue of massive scaling-up of our testing. we are going to need to give that covid-19 test to every possible flu patient. it also comes down to us having a really massive vaccination program for influenza so we can take that as much as possible out of the equation, and really building up our supply of in

david eisenman from ucla's center for public health and disasters. asked him what he thinks. >> the flu plus covid-19 at the same time, that's a one-two punch, so we were lucky this year the covid-19 arrived in march, which was the end of our flu season, but, you know, flu seasons are really busy times in hospitals. emergency rooms are typically stacked up with patients, beds against the walls, hospitals are filled. doctors' offices are filled. nursing homes have lots of cases and now imagine having a second respiratory virus and looks just like the flu coming around at the same time. it's going to make it incredibly important that we have tests for everybody. everybody is going to need both a flu test and a covid-19 test. so what this comes down to once again is the issue of massive scaling up of our testing. >> and a new preliminary study is warning that the anti-malaria drug hydroxychloroquine, that drug has been touted by many people including the president. it has shown no benefit in helping coronavirus patients and more deaths among coronavirus

david eisenman what it could tell us about the coronavirus. >> herd immunity is the protection that a population of people get, it's the indirect protection that they get when enough people are immune to the disease. they can get immune to it from either having the disease and recovering or from vaccination so i kind of think of it this way, if the -- if i get infected and i recover and everyone around me is immune from it already, it's harder for the virus to find someone new to infect. so the studies are very interesting. we'll look forward to the results. whether we can use them for our policies here, probably not. we can't allow people to become immune from getting infected. that's just not a policy we would tolerate in the united states. we can get to immunity once we have vaccines. >> this week we saw in wuhan, china, the city partially re-opened, but schools there are still closed and police are still taking people's temperatures before they get onto the subway. people's health is getting tracked on apps. what do you see the re-opening of american society looking like and do yo

david eisenman from ucla. and whether we should all be wearing a mask. >> the study shows first that we know that many people can spread the virus even without having symptoms or before they have symptoms. and we also have found studies now that show that normal speaking generates lots of small spit droplets, really too small for the eye to see, and the virus is contained in that saliva that's disbursed when we talk. so this may partially explain how people without symptoms are spreading the disease in those studies, and it appears that a mask or even a cloth covering your mouth can stop this emission. >> when it comes to testing, the president says he took a second test. it was much more pleasant. it was much faster. in his words. yesterday detroit became the first u.s. city to use what's called rapid test on first responders, medical professionals and city workers. what do we need to know about the new testing? >> there is a few things. one is that we don't really know how accurate it is. the current tests t

david eisenman. the latest research says this virus can be spread simply by talking and breathing, not just coughing and sneezing. what should people know about this latest study? >> it's a bunch of studies all put together. so yes, we're also going to now be recommending that masks are no longer for sick people only. so it comes from a few studies that we're saying now you need to cover your mouth and nose whenever you go out of your house and into public. the studies show first that we know that many people can spread the virus even without having symptoms or before they have symptoms. and we also have found studies now that show that normal speaking generates lots of small spit droplets, really too small for the eye to see. and the virus is contained in that saliva that's dispersed when we talk. so this may partially explain how people without symptoms are spreading the disease in those studies. and it appears that a mask or even a cloth covering your mouth can stop this emission. so more and more

david eisenman. is looking at california where cases are nowhere near the levels we've seen in new york have some herd immunity because they may have been exposed earlier to the virus, perhaps as early as last fall. what exactly is herd immunity, and what can it tell us about how we can get out of this crisis? >> herd immunity is the protection that a population of people get, it's the indirect protection they get when enough people are immune to the disease. they can get immune to it from either having the disease and recovering or from vaccination. so i kind of think of it this way. if i get infected and i recover, and everyone around me is immune from it already, it's harder for the virus to find someone new to infect. so if even 30% of the people around me are immune, it's harder for the virus to infect somebody. and kind of break the chain of transmission that the virus has, jumping from one person to the next. so you don't have to have everybody in a population immune. herd immunity says that i