Health Highlights: June 9, 2020

Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

New Coronavirus Introduced to California Several Different Times: Study

The new coronavirus appears to have arrived in California several different times, new genetic research suggests.

“We found out that there have been multiple introductions into California of different lineages of the virus,” study leader Dr. Charles Chiu, professor of laboratory medicine at the University of California, San Francisco, told CNN.

In the first few weeks after the new coronavirus first appeared in the United States, it wasn’t spreading freely across California, but was introduced in a number of separate incidents, according to the study published in the journal Science.

“It shows that there were several different sparks landing in Northern California, many of which fizzled out probably due to a combination of public health measures and luck,” evolutionary biologist Michael Worobey, who was not involved in the study, told CNN.

For the study, Chiu and colleagues analyzed the genomes of the new coronavirus that infected 36 people in nine California counties.

One finding was that an outbreak that infected more than 700 people on the Diamond Princess cruise ship in February most likely originated with one passenger who carried a strain that circulated widely in Washington state and elsewhere, Chiu told CNN.

Another outbreak in Solano County was limited to three people — a patient and two healthcare workers who cared for her. Contact tracing and quick isolation of the new cases prevented further spread, according to Chiu.

Even though it’s a small study, it helps show how a few cases can turn into a pandemic, and how rapid response can stop the spread, Chiu told CNN.


Spread of New Coronavirus by People Without Symptoms is Rare: WHO

The spread of the new coronavirus by people without symptoms of COVID-19 appears to be rare, a World Health Organization official said Monday.

“From the data we have, it still seems to be rare that an asymptomatic person actually transmits onward to a secondary individual,” Maria Van Kerkhove, head of the WHO’s emerging diseases and zoonoses unit, said during a media briefing, CNN reported.

“We have a number of reports from countries who are doing very detailed contact tracing. They’re following asymptomatic cases, they’re following contacts and they’re not finding secondary transmission onward. It is very rare — and much of that is not published in the literature,” she said.

“We are constantly looking at this data and we’re trying to get more information from countries to truly answer this question. It still appears to be rare that an asymptomatic individual actually transmits onward,” Van Kerkhove said.

She also said that asymptomatic cases of COVID-19 often turn out to be mild disease, CNN reported.

The new coronavirus “passes from an individual through infectious droplets. If we actually followed all of the symptomatic cases, isolated those cases, followed the contacts and quarantined those cases, we would drastically reduce — I would love to be able to give a proportion of how much transmission we would actually stop — but it would be a drastic reduction in transmission,” Van Kerkhove said, CNN reported.