Coronavirus pandemic in the US

Antibody tests used to determine if people have been infected in the past with Covid-19 might be wrong up to half the time, the US Centers for Disease Control and Prevention said in new guidance posted on its website. 

Antibody tests, often called serologic tests, look for evidence of an immune response to infection. “Antibodies in some persons can be detected within the first week of illness onset,” the CDC said.

They are not accurate enough to use to make important policy decisions, the CDC said.

“Serologic test results should not be used to make decisions about returning persons to the workplace.”

Why this matters: Health officials or health care providers who are using antibody tests need to use the most accurate test they can find and might need to test people twice, the CDC said in the new guidance.

“In most of the country, including areas that have been heavily impacted, the prevalence of SARS-CoV-2 antibody is expected to be low, ranging from less than 5% to 25%, so that testing at this point might result in relatively more false positive results and fewer false-negative results,” the CDC said. It’s a point that’s been made frequently in recent weeks by public health experts, but the CDC spells out the problem in the new advice on antibody testing.

A false positive will lead someone to believe they have been infected when in fact they have not been. There’s little evidence now about whether having been infected gives people immunity to later infection, but doctors worry that people will behave as if they are immune if they get a positive antibody test.

The new CDC guidelines echo advice from groups such as the University of Minnesota, which cautions against using antibody tests to make policy decisions.

The CDC explains why testing can be wrong so often. A lot has to do with how common the virus is in the population being tested. “For example, in a population where the prevalence is 5%, a test with 90% sensitivity and 95% specificity will yield a positive predictive value of 49%. In other words, less than half of those testing positive will truly have antibodies,” the CDC said.

“Alternatively, the same test in a population with an antibody prevalence exceeding 52% will yield a positive predictive greater than 95%, meaning that less than one in 20 people testing positive will have a false positive test result.”

Therefore, it is best to use tests with high specificity – which are unlikely to produce a lot of false positives – and in populations where doctors suspect there are many cases,” the CDC said.

Stocks closed sharply higher on Tuesday on optimism about a potential Covid-19 vaccine and the further reopening of the economy.

The three major stock indexes rallied all day, but they each finished below their session highs.

Here's where things closed:

Both the Dow and S&P fell short of closing above the key thresholds of 25,000 points and 3,000 points, respectively. They last closed above those levels in early March.

At least 27 states are now investigating cases of multisystem inflammatory syndrome in children, or MIS-C, a condition doctors believe could be linked to Covid-19. 

The Florida Department of Health told CNN on Tuesday it has “received information regarding seven confirmed cases of multisystem inflammatory syndrome (MIS) in Florida and is working to investigate, confirm and ensure the appropriate care for any other potential cases.”

Florida joins 26 other states and Washington, DC known to have potential and confirmed cases, totaling more than 350 children, according to a CNN survey of health departments across the country.

This represents just a small fraction of more than 1.6 million cases of Covid-19 currently being reported across the United States.

“You may not notice the disease emerge in a small group of 10 or 20,000 cases. But if you get to 90 or 100, or a million cases, that one is a very rare, potential side effect, or consequence of the infection can become apparent," Ryan added.

Maine is significantly increasing their contact tracing capacity by hiring more skilled staff and volunteers, adding innovative technology, and securing social services, Department of Health and Human Services Commissioner Jeanne Lambrew said. 

Right now the state has a contact tracing and case investigation team of about 30 people, but is looking to more than quadruple the team.

Here's what Lambrew said the state is planning to do:

The expansion of the contract tracing program will be paid for with federal dollars, Lambrew said, and it is estimated it will cost about $7.5 million.

The latest numbers: Maine is reporting 35 new cases of Covid-19, for a total of at least 2,109 probable cases statewide, Dr. Nirav Shah, the director of the Maine Center for Disease Control and Prevention said.

The state also announced one additional death related to Covid-19, bringing the total of deaths related to the virus in Maine to 79. 

Starting today, hair salons and barbershops can begin to reopen in California, but only in counties that have been approved to move forward in the state’s four-phased reopening plan, Gov. Gavin Newsom announced.

Of California’s 58 counties, 47 are moving forward with reopening, now including hair salons. These areas of regional variance have attested to stabilization in infection rates and proven that hospitals are ready with space, staff and personal protection equipment. Those areas include San Diego and Sacramento. The state’s two largest metro areas – Los Angeles and San Francisco – are still in the beginning phase of reopening.

Health guidelines for reopening barbershops and hair salons include having both workers and clients wear masks. Scissors, shears and smocks must be cleaned and disinfected between each client, as should chairs, headrests, combs and brushes.

Contactless payment services are encouraged, as are the removal of magazines in waiting areas.

These measures are accompanied by physical distancing and hand washing protocols.

The University of Colorado at Boulder plans to restart in-person learning for students for the fall 2020 semester.

The school chancellor said new changes will be implemented, including classes being divided into multiple sessions, and a unique plan to keep first-year students in small groups.

The cohort groups will be kept small. “We believe by reducing that population density will certainly help to mitigate some of the problems with the virus,” DiStefano said.

He added that while the school cannot control students from socializing with people outside of their cohort the campus will be “Covid ready by requiring our students to wear masks during the day while they are on campus.”

At the very least, the school can mitigate virus-related problems while students are on campus, DiStefano said.

More details on the school's plan: For academic instruction of the university's 35,000 students, the school plans to split single classes into multiple sessions and use larger spaces to reduce the number of students in classrooms.

It also plans to extend the class schedule to Monday through Friday, from 8 a.m. to 9 p.m., to decrease student density on campus.

Approximately 7,000 first year students will have a slightly different experience. Their housing assignments and class enrollment will be done by dividing students into "small cohort groups." Those groups will live together and have all their classes together. The plan did not specify how the university will enforce these groups not co-mingling.

The university said in order to be a "Covid-19-ready campus" it will have testing capability and rapid response teams for tracking and isolation on infected individuals to meet public health guidelines.

Watch full interview here:

This post has been updated with new details about the cohort groups.

If you have had coronavirus, or know someone who has tested positive, the US Centers for Disease Control and Prevention's new guidance contains information about how long you should stay away from others.

According to the guidelines, posted over the weekend, people who have been sick with coronavirus infections should stay away from other people until...

“Depending on your healthcare provider’s advice and availability of testing, you might get tested to see if you still have Covid-19. If you will be tested, you can be around others when you have no fever, symptoms have improved, and you receive two negative test results in a row, at least 24 hours apart,” the CDC said in the new guidance.

People who tested positive but had no symptoms can still infect others, and the CDC says people should wait for 10 days after a positive test before mixing with other people again.

And people who are exposed to someone with coronavirus need to stay at home for at least 14 days, the CDC said, since it can take that long for symptoms to develop.

Virginia Gov. Ralph Northam announced today that people 10 years old and older will be required to wear masks within a public indoor spaces in the state starting Friday.

People who are eating and drinking will be exempt.

Here's where masks will be required:

Northam apologized for an incident over the weekend where he was photographed while not wearing a mask.

Northam said he was approached by a group of people who wanted to take a picture with him.

Los Angeles County, California, will appoint an independent Inspector General to oversee nursing homes throughout the coronavirus outbreak. 

More than half of Covid-19 fatalities in Los Angeles County, accounting for more than 1,000 deaths, have stemmed from outbreaks at nursing homes.

County Supervisor Janice Hahn described it as “a pandemic within a pandemic in our skilled nursing facilities.” 

The inspector general will likely be in place by July and will be responsible for overseeing the health and safety of residents and staff. 

Auditing more than 300 facilities within the county, this person will ensure compliance with testing, training, staff levels, and mitigation plans, as well as oversee investigations of outbreaks.

On nursing home staff and administrations, Health Director Barbara Ferrer said, “This is in no way to a reflection on the fact that they’ve failed or have done something wrong. They’ve worked their hardest and done their best, but it hasn’t been enough.”

The measure also calls for development and implementation of a digital dashboard in which to collect and display the data.