COVID-19 Case Rates & BA.2: A Q&A With Our Health Officer, Dr. Jeff Duchin

In recent weeks, we’ve heard a lot about fluctuating COVID-19 case rates in other cities and countries, and the spread of the BA.2 variant. We sat down for a Q&A with King County’s Health Officer, Dr. Jeff Duchin, to get a better sense of what we’re seeing in King County.

Q: What are we seeing in terms of COVID-19 case and hospitalization rates?

Dr. Duchin: Big picture – new case and hospitalization numbers in King County are significantly lower than the peak we saw in January of this year. At that time, we were seeing an average of 6,500 new cases daily. Currently, we’re seeing an average of just over 300 new cases reported each day. It’s a similar story for hospitalizations – in early January, we had an average of 60 new COVID-19 hospitalizations daily, compared to an average of three to four currently. These metrics mean that King County is classified as “low” according to CDC’s COVID community level framework.

However, in the last two weeks, the number of new COVID-19 cases in King County has been increasing. We’ve seen a 91% increase in the last two weeks, from an average of 186 new cases daily the week of March 21, to an average of 356 new cases daily this week. Hospitalization rates have stayed relatively steady, hovering around two to four new hospitalizations per day since mid-March, and deaths have been falling since early February.

Because we’re starting at a relatively low baseline number of cases, hospitalizations and deaths currently, small increases lead to percentage increases that appears large compared to the actual size of the increase (check out this webpage for more info on this effect).

Although the number of cases is rising, hospitalizations right now are lower than what we’ve seen during most of the pandemic.

Q: How should we interpret this recent increase in cases? Do you think we’ll see another COVID-19 surge?

Dr. Duchin: It’s too soon to make any definitive statements about the course of our recent increase in cases. With what we’re seeing now, it’s not possible to accurately predict the timing or severity of potential future surges. My best estimate is that we will see a rise in cases that could last for several weeks, but I don’t expect the extent of the rise or the number of associated hospitalizations and deaths to be as severe as our recent wintertime Omicron surge.

Right now, for people who are fully vaccinated and boosted, the risk in King County of acquiring COVID-19, particularly of developing a serious infection, is greatly reduced compared to the peak of our recent Omicron surge early this year. COVID-19 cases, hospitalizations, and deaths have declined significantly from what we saw in January, and our vaccines and boosters provide a high level of protection against serious illness from COVID-19.

But, with increases in cases comes increased risk of infection in the community. We’re carefully watching and assessing the case and hospitalization trends to help inform public health guidance.

Q: What’s causing the recent increase in cases?

Dr. Duchin: There are lots of different factors that impact COVID-19 transmission, and these factors interact in complex ways. Factors influencing our recent increase in cases likely include the spread of the more contagious BA.2 variant locally, the relaxation of precautions (like loosening of mask mandates), and changes in behavior, such as more in-person group activities. The extent of a potential surge is also influenced by the level of protection we have against infection and serious illness from vaccination plus boosters, and recent infections.

Q: You mentioned the BA.2 variant. Are we seeing a rise in COVID-19 cases from BA.2 in King County?

Dr. Duchin: In recent weeks, we’ve seen an increase in COVID-19 cases caused by the BA.2 variant locally, in Washington state, and across the U.S. As of the week of March 20, 78% of King County COVID-19 cases sequenced by the University of Washington were the BA.2 Omicron variant.  

In other words – BA.2 is replacing other variants in King County, but we’re not seeing a large growth in cases overall at this time.

While BA.2 is highly contagious – it spreads more easily than the previous version of Omicron we just experienced – our current vaccines, particularly if someone is fully vaccinated and boosted, protect well against BA.2.  But it’s important to understand that the booster dose is needed for full protection against hospitalization and death.

Q: A lot of people have already had COVID-19. What do we know about natural immunity to BA.2 for people who’ve previously had COVID?

Dr. Duchin: The Omicron variant has three sub-lineages, BA.1, BA.2, and BA.3. BA.1 quickly became the dominant strain circulating globally and in the U.S. and was the cause of the massive surge seen in recent months. Now on the scene is BA.2, which can be thought of as a cousin of BA.1. That means people who were previously infected with the Omicron BA.1 variant may have some immunity to BA.2. This may help protect against a particularly large BA.2 surge in King County and the U.S., as so many people were recently infected with Omicron.

However, studies show that people who were infected with COVID-19 prior to the Omicron BA.1 surge likely don’t have much protection against the BA.2 variant. And even if you were previously infected, vaccination increases your level of protection.

The bottom line is that our current vaccine and boosters are effective against serious infections from BA.2 and other variants of COVID-19 – more so than immunity from a previous infection. Getting vaccinated and boosted is the best thing you can do to protect yourself and your family from serious illness from COVID-19.

Q: What are your recommendations for the public at this point?

Dr. Duchin: People should be aware of the increasing trend in cases and take precautions. When cases are increasing, all COVID-19 prevention measures become more useful.

One of the most important elements is making sure you’re not just fully vaccinated, but that you’ve also received your booster dose. We have excellent vaccination rates in King County (85% of residents ages 12 years and older are fully vaccinated), but we’re not seeing the same excellent rates in terms of getting a booster dose (55% of King County residents ages 12 years and older have received a booster dose).

In order to protect against serious infection, everyone ages 12 years and older should get a booster dose with an mRNA vaccine at least five months after the second dose of Pfizer or Moderna, or two months after one dose of J&J. Even if you’ve already been infected with COVID-19, the booster is key to keeping up your immunity. And, those who are age 50 years or older or who are immunocompromised are now able to get a second booster dose, based on CDC’s new guidance. People who had two doses of the J&J vaccine (a J&J primary dose followed by a J&J booster) should also get an mRNA vaccine booster at least four months after the J&J booster. More information about booster guidance is available from the CDC.

It’s important to understand how important good indoor air quality and ventilation is to prevent the spread of COVID-19. Now is a great time for everyone to work to improve the indoor air quality in their home or business. Check out our blog post on ventilation and guidance from the U.S. Environmental Protection Agency for more info.

High-quality well-fitting face masks, of course, also remain an important way to decrease your risk of infection, especially when COVID-19 spread in the community is increasing. It’s appropriate for many people to continue to wear high-quality face masks (N95, KN95, KF94) in crowded indoor settings if they have weakened immune systems or are at increased risk for severe disease, are unvaccinated, or are in contact with someone at high risk. Some people may choose to wear a mask out of consideration for people who may be at high risk in public settings, or if they want to further reduce their own risk for any reason. 

And, if you do develop COVID-like symptoms, even if they’re mild, isolate yourself from others and get tested for COVID-19.

Originally published April 6, 2022.