October 5, 2020

Science and outcomes

Seattle was the epicenter of the Covid-19 pandemic when it first arrived in the US. We didn’t really know what to expect, but feared the worst based on what we saw in Wuhan, China. That is when I wrote my first brief post about the pandemic. Luckily, the initial outbreak got everyone’s attention, including the governor, the mayor, the health department, hospitals, tech companies, and citizens. Our city shutdown pretty quickly and we amazingly avoided the scenario we were preparing for. We thought we were headed for an overwhelming surge, like New York City and New Orleans eventually had, with hospitals overwhelmed and many deaths.

But the surge never came and still isn’t here. Data shows that Seattle has the lowest rate of Covid-19 cases among major US cities. I attribute it to our leaders, our health department, and our citizens, taking Covid-19 seriously and having empathy and care for others. Ok, maybe a little bit the Seattle Freeze.

It has been a long 7 months. We have faced lots of challenges, but people have kept their distances, worn their masks without complaining, and the number of infections shows that. Despite the large Black Lives Matter protests, infections did not rise. An analysis shows this is also true across the country due to the protests being outdoors, with natural distancing, and almost everyone wearing masks.

Of course, despite our success, there are challenges and failures. Salish Lodge and Spa has been dealing with an outbreak at their hotel/restaurant by Snoqualmie Falls. They are also dealing with the fallout and controversy about not notifying the public. UW is trying and failing to contain an outbreak on its “Greek Row” area of frat houses. Overall, though we have done well to contain the virus.

Which brings us to the CDC’s once again changing their tune back to Covid-19 transmission can be airborne. Airborne transmission explains many of the superspreader events which are traced to one or two people infecting people in close quarters without masks. The Atlantic has an excellent in-depth article about how to think about transmission of SARS-CoV-2, the virus that causes Covid-19. I have talked before about the R0 (R naught) which is the number of people one infected person, on average, infects. But really we should be thinking about a different concept, dispersion, or k, because many people with SARS-CoV-2 don’t infect anyone, but a few people cause most of the new infections as superspreaders. These clusters of infections are forms of overdispersion. The concept needs more attention, especially since we just had an example at the White House reception for Judge Amy Coney Barrett. The ceremony was outdoors with 150 people sitting knee to knee, but the reception was indoors, with few people wearing masks. Not all cases are yet accounted for. I expect there to be more. Other superspreader clusters also involved prolonged contact in poorly-ventilated indoor spaces with minimal people wearing masks .

These are reasons why sticking with our imperfect but effective techniques of washing our hands, wearing masks, keeping a good distance outdoors or in an area with good ventilation, and for shorter periods. These add up to very effective ways to avoid dispersal of the virus, why Seattle nailed it and flattened the curve. We hope to make it through the winter without a surge, but it will be a challenge as life moves indoors. We can do this until a safe and effective vaccine is available. We have done it for 7 months.

Wash your hands, cover your nose, keep safe six, outdoors as much as possible. We know what works.