The science behind Oregon’s surge, new restrictions, and vaccination guidelines

By Erin Ross (OPB)
April 30, 2021 1 p.m. Updated: April 30, 2021 7:24 p.m.

For five weeks now, COVID-19 cases in Oregon have been surging. Friday, fifteen counties will fall under new social-distancing restrictions to curb the virus’ spread.

Here’s everything you need to know about the coronavirus variants currently driving infection, new restrictions, updated guidelines for the vaccinated and unvaccinated, and the science underlying them.


Much of Oregon is under new social distancing restrictions effective on Friday, and the CDC has released new guidelines. What is the science behind them?

Closing restaurants and indoor dining:

Eating indoors has been consistently listed among the most COVID-19-dangerous activities. When you eat inside, you remove your mask. And depending on the air circulation in a room, tiny droplets of water and virus can remain in the air for a very long time, said Chunhuei Chi, the director of Oregon State University’s Center for Global Health.

Raising the maximum number of outdoor diners from 50 to 100 per establishment:

“Since the start of the pandemic, the evidence that this virus is hard to transmit outdoors has been very strong,” Chi said. Fences, tents, and canopies can increase the chances of the virus transmitting, and it’s still important to wear a mask when you aren’t eating or drinking.

Related: Surge in COVID-19 hospitalizations triggers new restrictions across much of Oregon

Limiting capacity at gyms, pools, and other indoor sports facilities:

“When you exercise, your metabolism is much faster,” Chi said. “If you are a carrier, then potentially there will be more virus exhaled in the air.”

Limiting capacity at outdoor pools and other outdoor sports facilities:

Relatively speaking, it’s safer to do sports outside than it is to do them indoors, but sports still represent a high risk.

“For the kind of sports that involve very close physical contact, a mask is very important. Even though it’s outdoor,” Chi said. It’s important that spectators are kept far apart. Like running, cheering for your favorite team puts out a lot of virus.

Take it outside

The most dangerous activities involve chanting, yelling, singing, exercising, and playing wind instruments. Wearing masks and taking those activities outside makes them much safer.

“Last year I was following the continuous protests in the Portland area,” Chi said. “The vast majority were wearing masks, and the cases did not rise.”

Colin Rath (right) one of the owners of Migration Brewing, is frustrated governor Brown may impose new dining restrictions, “It’s a whole lot of a guessing game. Staff don’t know what to plan on. Guests don’t know what to plan on.”

Colin Rath (right) one of the owners of Migration Brewing, is frustrated governor Brown may impose new dining restrictions, “It’s a whole lot of a guessing game. Staff don’t know what to plan on. Guests don’t know what to plan on.”

Kristian Foden-Vencil

Masks, masks, everywhere:

The CDC recently released new mask guidelines for the vaccinated and unvaccinated. In other states, it can mean big changes. But in Oregon, where public spaces have been open for much of the pandemic, not much has changed. If you are indoors, in most cases the CDC recommends everyone wear a mask. If you are outdoors and it is not crowded, you probably don’t need a mask. More detailed information can be found in the CDC’s charts, here.

Cases are going down in the U.S. Why are they going up here?

This is difficult to say. There are a lot of potential factors.

For much of the pandemic, the prevalence of COVID-19 in Oregon has been low, compared to other states. That means that fewer unvaccinated Oregonians have some level of immunity to the COVID-19 virus. Simply put, there could be more people here to infect.

The weather is another possibility.

”It’s April. People have spring fever and want to get outside,” Brett Tyler said. Tyler is a principal investigator at Oregon State University’s TRACE project, and the director of OSU’s Center for Genomic Research and Biomedical Computing. TRACE has been conducting randomized studies to estimate the prevalence of COVID-19 in different Oregon communities since the early months of the pandemic.

But there’s another possibility, and it’s also something TRACE monitors: different, more infectious COVID-19 variants.

What versions of the virus are making Oregonians sick right now?

When the U.S. first documented new COVID-19 variants circulating, Oregon was somewhat spared. While cases on the East Coast and in the Midwest surged because of the more infectious and more deadly B.1.1.7 variant first found in the United Kingdom, the West Coast saw its own, homegrown variants emerge. The two Californian variants, B.1.427 and B.1.429, are only slightly more infectious than the original virus.


But in March, that started to change. And by the first week of April, B.1.1.7 had become the most common coronavirus variant circulating in Oregon.

“The fraction in the sequence cases in Oregon reported to are going up very sharply for B.1.1.7,” Tyler said. “It went up from 10% [of cases sequenced in Oregon] to 60% from March 14 through April.”

It’s not clear what caused B.1.1.7 to take off so rapidly. It is among the most contagious COVID-19 variants found so far. It’s also possible, Tyler said, that spring travel could have brought more cases of B.1.1.7 to Oregon. Data for April is still incoming.

The good news: all vaccines available in the U.S. are very effective against B.1.1.7. Other variants — like P1, first identified in Brazil and B.1.351, initially detected in South Africa — do appear to be a bit better at getting around vaccines, but have been much less common.

“They’re both here, they make up about 2-to-6% of cases, but it’s not dramatically increasing in any way,” Tyler said. Because vaccines may not be as effective against them, “we’re keeping a very close eye on them.”

Who is getting sick?

In Oregon and across the country, hospitals have seen a big shift in the types of patients they’re treating. Throughout most of the pandemic, the most severe cases of COVID-19 have been in older adults and people with underlying conditions.

Most people in those groups are now fully vaccinated, so they’re much less likely to catch COVID-19. Ideally, that would mean hospitals would be seeing very few cases, since younger adults were less prone to severe infection.

But that’s changed in the last few weeks. In Oregon, more and more young people are getting seriously ill from COVID-19.

“In the past few weeks we are caring for more patients with COVID in our (intensive care units) who are sicker, younger, and without underlying medical conditions,” Oregon Health & Science University Chief Medical Officer Dr. Renee Edwards said in a press conference April 23.

The idea that B.1.1.7, and potentially other variants, could be behind these severe cases in young, healthy adults is supported by anecdotes from around the world. Michigan also saw intensive care units full of youthful patients, as did the U.K. late last year.

Right now B.1.1.7 and another variant have been implicated in the outbreak in India.

”The current wave of COVID has a different clinical behavior,” Dr. Sujay Shad, a senior cardiac surgeon at Sir Ganga Ram Hospital in India, told the New York Times, “It’s affecting young adults. It’s affecting families. It’s a new thing altogether. Two-month-old babies are getting infected.”

What is the latest research on vaccine efficacy?

These vaccines work. A vaccine is the best way — besides never getting exposed — to prevent hospitalization from COVID-19. And even though some vaccines are less effective against some variants, they make you much less likely to be hospitalized or die.

A study released on Wednesday by the Centers for Disease Control and Prevention found that adults over 65 who received both doses of either the Pfizer or Moderna COVID-19 vaccine were 94% less likely to be hospitalized than unvaccinated people of the same age.

It also appears that people vaccinated for COVID-19 are significantly less likely to spread the disease.

Is one shot enough? Can I just be half-vaccinated?

One-shot confers some protection, so once you get it, you can breathe easier. But you can’t let your guard down. The same CDC study found that a single dose of either vaccine made adults just 64% less likely to be hospitalized.

Why do I need to distance if I’m vaccinated?

It is important to follow social-distancing guidelines if you are vaccinated, Tyler said. It’s even more important if you are half-vaccinated.

“Think of it like, how if you don’t take a full course of antibiotics, you can evolve antibiotic-resistant bacteria,” Tyler


Seven needles filled with vaccine doses sit on a table next to the gloved hand of a medical worker.

COVID-19 vaccine preparation at a drive-thru vaccination clinic at Portland International Airport, April 9, 2021. The clinic is a joint operation hosted by Oregon Health & Science University, the Port of Portland and the American Red Cross.

Kristyna Wentz-Graff/ OPB

Right now, there is a lot of virus circulating in Oregon. About a quarter of the state is fully vaccinated, and about an equal amount has received just one dose. That means the odds of the right virus finding a person with the right weakness is fairly high. A virus that succeeds in spreading among people who have only received one dose of the shot could, eventually, become better at spreading in people with both doses. By social distancing now, we are decreasing the chances of vaccine-resistant coronavirus variants evolving.

When can I be around other people?

It’s possible to catch COVID-19 in the first few days after receiving your shot, and, indeed, when you get the shot. Even though immunity reaches full strength in just a few days, the CDC recommends waiting at least two weeks before considering ‘safe.’

Tyler suggests taking it even further. “We’ve seen a few cases where people tested positive after two weeks. But they caught it ten days earlier.” That would be before they developed full immunity.

So if you can wait a few extra days before re-entering society, do it.