Coronavirus research tests reinfection, spread facts

Six feet or 13 feet apart? Two weeks or a month to recover? If you get it once, can you get it again?

Globally, the coronavirus has sickened more than 2 million people and killed more than 128,000 as of Wednesday, data from Johns Hopkins University shows.

And the U.S. has the most cases, with more than 609,600 infections and 26,000 deaths.

Here is some of the latest research on the coronavirus.

Can you be infected with COVID-19 again after you recover?

In South Korea, 133 people have retested positive for the coronavirus as of Wednesday, according to the Korea Centers for Disease Control and Prevention (KCDC).

“Investigators are looking into whether the cause of relapse is the virus being reactivated or reinfection with the virus. We are also investigating whether relapse cases lead to secondary infection,” KCDC chief Jeong Eun-kyeong said this week, the Yonhap News Agency reported.

Patients in South Korea must test negative for two tests within 24 hours before being deemed as fully recovered and released from quarantine. Health authorities reportedly have said the coronavirus was likely to have been “reactivated” rather than people getting reinfected.

Dr. William Schaffner, an infectious disease specialist at Vanderbilt University, said some explanations could be that those who recovered could still be excreting the virus in small amounts, or there was an error with testing or in the laboratory that led to cross contamination. He said more data about the patients who retested positive in South Korea is needed.

The World Health Organization has said it would look into why people are retesting positive for the coronavirus.

Amesh Adalja, a senior scholar for Johns Hopkins Center for Health Security, said he does not think people are becoming reinfected so soon after recovery.

“What may be occurring is that the test toggles between positive and negative and those who have recovered because of the operating characteristics of the test. It is also the case that there could be debris and remnants of the virus’ RNA that could be causing a positive reaction,” Dr. Adalja said.

How far can the virus travel?

Health officials recommend staying 6 feet from another person, but a team of researchers suggests the virus can be transmitted farther than that.

A group of researchers in China collected swab samples from potentially contaminated objects in an intensive care unit and a general COVID-19 ward at the Huoshenshan Hospital in Wuhan, the city where officials say the coronavirus outbreak began. The research team also sampled indoor air and air outlets to detect aerosol exposure.

The team split the ICU workplaces into high-risk and low-risk areas to monitor aerosol results. In high-risk patient care and treatment areas, the positive rate of the coronavirus was 40.6%, compared to 12.5% in the low-risk doctors’ office area.

By examining aerosol distribution, the researchers concluded that the transmission distance of SARS-CoV-2 (the official name for the coronavirus) could be just over 13 feet, says the study, which was published earlier this month in a journal published by the Centers for Disease Control and Prevention.

“The findings … do not include data on whether the virus was viable and able to make people sick at a distance of 13 feet,” said CDC spokeswoman Kristen Nordlund. “The small amount of virus particles detected at 13 feet was not only the lowest of any sample the investigators assayed, but it was only weakly positive.”

Dr. Schaffner said 3 to 6 feet is the “standard” physical spacing recommendation for the flu and other respiratory viruses.

“As we go out from an individual who’s infected, you have more virus close in, and the farther out you go, you get less virus because of the exhalation,” said Dr. Schaffner. “Three to six feet seems reasonably practical. Is it perfect? Does it contain every viral particle? No. But it’s a reasonable guideline. People can understand it and they can introduce it into their daily lives.”

Are there additional COVID-19 symptoms?

Researchers at UC San Diego Health have offered more evidence that links loss of smell and taste to COVID-19 infections.

“Based on our study, if you have smell and taste loss, you are more than 10 times more likely to have COVID-19 infection than other causes of infection,” Dr. Carol Yan, one of the researchers and a head and neck surgeon at UC San Diego Health, told the university’s news center. “The most common first sign of a COVID-19 infection remains fever, but fatigue and loss of smell and taste follow as other very common initial symptoms.”

The team surveyed 1,480 patients with flu-like symptoms and concerns about possible COVID-19 infection. The patients underwent testing at UC San Diego Health from March 3 to March 29.

Of the total, 102 patients tested positive, while 1,378 tested negative. The study, published Sunday in the International Forum of Allergy & Rhinology journal, included responses from 59 patients who tested positive and 203 patients who tested negative for COVID-19.

How long does it take to recover and no longer be infectious?

Coronavirus symptoms such as fever, dry cough and shortness of breath may appear two to 14 days after exposure.

Under federal health guidelines, people with COVID-19 symptoms who were instructed to self quarantine can discontinue isolation if at least three days have passed since recovery (which means the fever is gone without the use of medications), respiration has improved and at least seven days have passed since symptoms first appeared.

“A rough guide for other infections is that infectiousness drops when the fever subsides,” Ben Cowling, a professor of public health at the University of Hong Kong, told NPR.

Meanwhile, Dr. Aaron Carroll, a professor of medicine at Indiana University, told NPR there’s still some uncertainty. “We still don’t have enough data to really know how long people are infectious,” he said.

For mild illness, Dr. Schaffner said the two-week time frame seems pretty accurate for recovery time. However, those with severe illness could take longer to recover.

What tests are available? What treatments are being tested?

The Food and Drug Administration has approved the first saliva test to detect coronavirus, allowing for “broader population screening” than the current method of using nose and throat swabs, Rutgers University announced Monday.

So far, the FDA has issued 34 emergency use authorizations for diagnostics tests and more than 180 labs have begun testing under the guidelines set by the federal agency.

The FDA said Tuesday that it has not authorized any at-home testing for COVID-19, including self-collection of samples with or without the use of telemedicine.

The agency said it is working with developers toward approving at-home tests and has to consider issues such as whether the test user can safely and properly collect specimens and whether test samples can be properly shipped.

Last week, the first blood purification system received FDA approval to treat adults with serious cases of coronavirus.

The system, which is for patients 18 years old and older who have been admitted to intensive care with respiratory failure, reduces the amount of proteins in the bloodstream that control a cell’s immune response — known as cytokines — by filtering the blood and returning the filtered blood to the patient.

There are a number of therapies for COVID-19 in development and undergoing clinical trials including remdesivir, hydroxychloroquine, plasma therapy and a monoclonal antibody.

The National Institutes of Health announced a new study last week to determine how many adults in the U.S. without a confirmed history of coronavirus infection have antibodies, which indicates a prior infection.

The researchers aim to collect and analyze blood samples from as many as 10,000 volunteers to learn how much the coronavirus has spread undetected in the country and to gain insight into which populations are most affected.