While the world has launched frantic efforts to stop the spread of the new coronavirus and Oregon’s governor just announced the state’s K-12 schools will soon close for the rest of the month, the question turns once again to just how contagious is COVID-19?
If you get it, how long will you be sick?
And once recovered, can you catch COVID-19 again?
Read on for some commonly asked questions about the virus that is bearing down on the world.
HOW CONTAGIOUS IS COVID-19?
It appears that it’s more contagious than the flu. The R0 -- pronounced the R-naught -- for the flu is 1.3 to 1.5. That means each infected person typically spreads the flu to 1.3 to 1.5 people.
If the R0 of a virus is less than 1, it will eventually die off the face of the Earth.
A flurry of studies have been done to determine the R0 of the new coronavirus -- with half a dozen that appeared to use sound mathematical methods finding that it spread to about 1.5 to 6.5 people. The average was about 3.28 people.
That pales in comparison to a leader in infectious diseases, measles. It’s believed to have an R0 of between 12 and 18 people by drifting across rooms and lingering in the air for hours. But thanks to mass immunizations, measles was declared eradicated in the U.S. in 2000 -- before an anti-vaccine movement rose in popularity and the disease re-emerged with numerous outbreaks, scientists say.
Experts say when a vaccine is developed for the new coronavirus, its ability to so effectively spread will drastically decline. But the development of a vaccine is still at least a year to 18 months off, by optimistic estimates.
In the meantime, the medical world will continue to furiously work on better treatments to lessen the death rate.
As of early Friday, 30 people had been diagnosed in Oregon and more than 1,700 nationwide. More than 40 had died, according to The New York Times’ tracker.
IF I GET IT, HOW LONG WILL I BE SICK?
The incubation period is thought to be an average of five days -- that is the time between when a person is exposed and that person starts to show symptoms. Researchers have found that the incubation period could be as long as 14 days, although it is possible it’s longer for a tiny number of people.
A study published in the Journal of the American Medical Association followed the illness’ progression in four medical providers in January and February in Wuhan, China, the epicenter of the pandemic. The study found that 12 to 32 days passed from the time they first showed symptoms to when they were deemed recovered.
According to the World Health Organization, people with mild illness typically recover in about two weeks, and it can be up to six weeks for people with severe illness.
Anecdotally, we know that a Forest Grove woman, Rebecca Frasure, was isolated in a Tokyo hospital room for 28 days. She had been plucked from the Diamond Princess cruise ship in Japan in early February.
She said that long after her light cough and slight fever dissipated, she remained quarantined because she kept testing positive for the virus. She was released after two consecutive negative test results.
On Tuesday, Frasure and her husband, Kent Frasure, returned home to Oregon. Her husband never tested positive for the disease.
ARE PEOPLE WHO RECOVER FROM COVID-19 IMMUNE FOR LIFE?
The best answer that scientists at this time can offer is “the answer is unknown.”
There is so much that still needs to be learned about the novel coronavirus. But studies of other coronaviruses have shown that immunity does wear off over time. And the question is how long might immunity to COVID-19 last -- months or years?
A study published by the U.S. Centers for Disease Control and Prevention focused on nine survivors of Middle East Respiratory Syndrome (MERS), another coronavirus. The study found that the two who suffered the severest pneumonia from the disease still had immunity after 18 months.
But the immunity seemed to wane the less serious the bout with the disease had been.
Three patients who had suffered a more moderate pneumonia all had detectable antibodies in their system three months later. After 10 months, only one of the three did, according to the study published by the U.S. Centers for Disease Control and Prevention.
The remaining patients who had had only a mild reaction to the disease or had shown no symptoms had no detectable antibodies in their systems when tests were later run.
Some scientists say if individuals’ immunity to COVID-19 lasts on the course of years and not a few months, the spread of the disease might noticeably begin to slow when 50 percent or more of the population has been infected and recover. This is known as “herd immunity.”
WHAT ABOUT REPORTS OUT OF CHINA AND JAPAN OF FORMER PATIENTS BECOMING SICK AGAIN?
In late February, reports emerged of a Japanese tour bus guide who had become infected by the new coronavirus in January. The condition of the Osaka woman, in her 40s, improved, and she tested negative in early February. Three weeks later, she came down with chest pain and tested positive.
The study of the four medical providers who fell ill from the virus in Wuhan noted that all four were discharged from the hospital or home quarantine after their fevers had been gone for at least three days, they no longer had respiratory symptoms and throat swabs tested negative for the new coronavirus.
The four were tested again five to 18 days later, and their tests came back positive.
Virologists or researchers in both the Japanese and Chinese cases suspect that the patients weren’t re-infected so soon. Rather, they might have harbored low levels of the virus that weren’t detected from the throat swabs.
The Wuhan study concluded that the medical system might need to reconsider its standards for releasing COVID-19 patients from the hospital or from home quarantine orders because it’s unknown if people whose bodies still have detectable levels of virus can spread the disease to others.
SO CAN ‘RECOVERED’ PEOPLE STILL SPREAD THE VIRUS?
Because so many Oregonians -- as well as Americans nationwide – haven’t been able to get tested, the Oregon Health Authority has stressed that one sensible way to lessen the spread of the disease is to stay home if you have flu-like or cold-like symptoms. In particular, that’s a fever (found in 88 percent of patients in a massive Chinese study) and a dry cough (found in 68 percent of those cases).
So for those many Oregonians who want to get tested but haven’t been able to, the Oregon Health Authority recommends staying home for at least 24 hours after they feel better.
But some studies have found that the new coronavirus is detectable in saliva, mucus or stool days or a few weeks after people think they’ve recovered.
Some scientists are skeptical that people are still contagious at this point.
Dr. Richard Leman, who is on the Oregon Health Authority’s COVID-19 response team, said that people are most effective at spreading the virus when they cough or sneeze on other people.
A student at South Meadows Middle School in Hillsboro tested positive on Saturday showing mild symptoms. Health officials have said the child will return to school after those symptoms disappear.
When asked by The Oregonian/OregonLive on Wednesday if the child will be required to test negative before returning to school, Leman said that’s yet to be decided.
“We are working with an advisory group in order to help us make that decision,” Leman said.
Also of concern in the larger scientific community is whether people are contagious before they realize they’re sick. Some research has found that people infected with COVID-19 are shedding the virus even before they show recognizable symptoms, and the question is how contagious these people are that early on. On top of that, some people are infected but never show symptoms, and epidemiologists want to know how effective these people are at transmitting the virus to others.
IF I’M A PARENT, IS MY CHILD GOING TO GIVE IT TO ME?
Research so far shows that children rarely become seriously ill from the new coronavirus. A study of about 55,000 patients by the Chinese Center for Disease Control and Prevention registered no deaths of anyone 9 years or younger.
The Oregon Health Authority and the Hillsboro School District had used this as a reason for keeping South Meadows Middle School open after the student was diagnosed. Officials said they didn’t want to disrupt the learning process and in particular school closures disproportionately affect low-income students who rely on schools for meals.
Late Thursday, Gov. Kate Brown said that she would close the state’s K-12 schools starting Monday until April 1 -- not because she thought it was the best step toward stemming the virus’ spread. But she indicated that many others feel differently – acknowledging parents who’ve pulled their kids out of school and superintendents who’ve said they’re concerned for the health of staff who are over 60 years old or have underlying health conditions, the groups hardest hit by the disease.
“I have heard from superintendents, school board members, teachers, parents, and students that it has now become impossible to functionally operate schools due to workforce issues and student absences,” Brown said.
State health officials said they believed schools should be kept open because children are the least likely to be affected by COVID-19. But some scientists say what needs to be studied is if and to what extent children -- who might show no symptoms at all -- spread the disease to other adults, like their parents, who then in turn could spread it to co-workers or other adults.
Leman, the Oregon Health Authority doctor, said he thinks people who are no longer showing symptoms or who never showed symptoms are unlikely to spread the disease -- that the primary method of transmission is sneezing or coughing.
He said parents can help prevent getting sick themselves by practicing social distancing at home, even with their children.
“A parent who is taking care of that kid needs to avoid getting nailed by a cough,” Leman said. “We all together need to be staying a little farther away from other people than we usually do just in case that other person is ill. That’s one of our strategies.”
HOW HARD WILL THIS DISEASE HIT?
That’s widely debated. Some epidemiologists estimate that 20 to 70 percent of the world’s population could become infected.
The actual number depends, in part, on how dramatically and quickly governments, companies and other private entities act to effectively stop the virus’ rapid spread.
Michael Osterholm, the director of the Center for Infectious Disease Research and Policy, said on the “Joe Rogan Experience” podcast that his center conservatively estimates 96 million of people in the U.S., population 330 million, will come down with the virus in the next three to seven months without dramatic interventions. Of those, 48 million will be hospitalized and 480,000 will die without some sort of drastic change.
A study out of China, where the virus is believed to have crossed from wild bush animals to the first human last November, 80 percent of people who tested positive for the virus were able to recover at home while 20 percent required hospitalizations.
But in Italy, according to numbers from early March, about half of the people with confirmed cases were being hospitalized. It’s believed that a big reason for that is Italy’s large elderly population. The country is the hardest-hit nation after China and reported Thursday that more than 15,000 people have been infected and more than 1,000 have died.
Studies have shown different rates of death. A February study out of China found the death rate to be 2.3 percent -- with a higher death rate among those over 60 years old or with underlying conditions like heart and lung problems. The World Health Organization estimated the global death rate at 3.4 percent. But some scientists think it’ll be closer to 1 percent.
Osterholm said comparing China’s numbers to the U.S. might not be fair -- given that there’s a big difference in the populations of both countries. About 40 percent of American adults are obese, compared to 15 percent of Chinese adults -- and obesity could hinder the American survival rate, he said.
-- Aimee Green; agreen@oregonian.com; @o_aimee
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