People in their 20s continue to be the most likely to test positive for coronavirus, the Oregon Health Authority said Wednesday.

More than one in five diagnoses since the start of the pandemic has been of a 20-something adult, but this age group is far less likely to be hospitalized or to die after infection. The virus continues to be most deadly to older adults, and has been fatal to one in five people diagnosed after the age of 80.

A breakdown of severity and rates of COVID-19 by age group in Oregon found that:

• 855 children age 9 and younger have been diagnosed with the virus, 2.1% of them were hospitalized, none have died.
• 1,953 children and teens age 10-19 have been diagnosed with the virus, 1% of them were hospitalized, none have died.
• 4,202 people age 20-29 have been diagnosed, 2.5% were hospitalized, one has died.
• 3,385 people age 30-39 have been diagnosed, 4.2% were hospitalized, three have died.
• 3,220 people age 40-49 have been diagnosed, 6.3% were hospitalized, five have died.
• 2,470 people age 50-59 have been diagnosed, 10.8% were hospitalized, 20 have died.
• 1,593 people age 60-69 have been diagnosed, 20.1% were hospitalized, 61 have died.
• 977 people age 70-79 have been diagnosed, 33.3% were hospitalized, 86 have died.
• 681 people age 80 or older have been diagnosed, 36.6% were hospitalized, 152 have died.

Positive test results, hospitalizations climb

The Oregon Health Authority released its weekly report Wednesday, with a review of COVID-19 data from the week of July 27 through Aug. 2.

It found that the percentage of tests returning a positive result has increased from 5.1% to 6.4%. That’s still better than the national average of 8.7% positive test results, according to Centers for Disease control figures.The World Health Organization advises that positivity rates should be at 5% or lower for two full weeks before communities begin to reopen.

The state report said that 141 people were hospitalized in Oregon with the coronavirus in the most recent week, up from 127 people a week earlier.

In most cases, health officials were not able to identify how newly diagnosed people became infected.

Oregon nears 20,000 diagnoses

Oregon edged closer to its 20,000th coronavirus diagnoses Wednesday, as health officials announced 299 new confirmed and presumptive COVID-19 cases. That means 19,979 people have been diagnosed with the virus in Oregon since the pandemic's start, with 4,037 confirmed recoveries.

The Oregon Health Authority also reported five more deaths due to the coronavirus Wednesday:

• An 87-year-old Clackamas County woman who died at home. She tested positive on July 8, but state officials had not confirmed the date of her death. She had underlying health conditions.
• A 74-year-old Umatilla County man who tested positive on July 17 and died July 28 at a hospital in Kennewick, Washington. He had underlying health conditions.
• A 74-year-old Umatilla County man who tested positive on July 12 and died Aug. 1 at St. Anthony Hospital in Pendleton. Officials were not able to confirm whether he had underlying medical conditions.
• A 67-year-old Washington County man who tested positive on July 20 and died Aug. 3 at Kaiser Westside Medical Center in Hillsboro. He had underlying medical conditions.
• An 83-year-old Josephine County man who tested positive on July 19 and died Aug. 3 at his home. He had underlying medical conditions.

Related: COVID-19 by the numbers

How does the weather affect the spread of COVID?

When the outbreak first started in the winter, many people looked forward to the summer with hopes that the warmer weather would make it harder for the new coronavirus to spread. Weather does play a role in the proliferation of illness spread — think about cold and flu seasons in dry, winter months — but does it hold true for this new coronavirus?

So far, there isn’t enough data to say for certain. And recent spikes across the nation complicate the picture. But OPB spoke with Dr. Dawn Nolt, the medical director for infection prevention and control at Doernbecher Children’s Hospital, about what science knows about the effects of weather on viruses.

Related: The weather can affect the spread of coronavirus. Here’s how