A lot has happened in the six weeks since I first posted on the Wuhan coronavirus, now called COVID-19. In mid-January there were a handful of cases, not a lot of data, and almost no cases outside of one province in China. All three of those situations have changed somewhat, and with several confirmed cases and (as of this writing) six deaths in Washington state, it’s worth pausing for a moment and taking a hard look at what we know now.
After initially clamping down hard on communications regarding the virus, the Chinese government reversed course and opened up. And now that the number of cases there are in the tens of thousands, the medical community in China is starting to publish studies that give us important insights into COVID-19, papers that tell us how quickly it spread, the major symptoms, which cases tend to become critical or fatal, and the results of various treatments.
An important caveat when reading these studies is that they are specific to China’s outbreak, and the extent to which they apply to the rest of the world is unknown. That is a theme that will come up frequently as we discuss the results.
We now know something about how quickly COVID-19 spreads, as a number of studies in China have estimated its “reproduction rate,” also known as “R0”. An R0 rate for a disease is an estimate of the number of people an infected individual will tend to pass the infection on to when the population is not taking active measures to prevent spread and no vaccine is available. In China, the COVID-19 R0 rate has been estimated in several studies to be in the range of 1.3 to 3.0. To put this in context, here are the R0 values for other diseases:
1918 Spanish Flu: 1.8 – 2.0
Seasonal influenza: 1.5 – 3.0
Measles: 10 – 15
Pertussis: 16 – 18
Polio: 8 – 12
An R0 of 1 indicates a stable population of sick people that isn’t growing, whereas an R0 of 2 represents a population that is doubling in size with every new generation as it’s passed along. It’s important to understand, however, that the R0 for COVID-19 isn’t an inherent property of the virus; it’s affected heavily by the context of the population that it is spreading through. Populations with poorer sanitary standards and more close social contact will see higher R0 values; though populations that physically isolate infected persons and/or employ effective treatments will see lower values. Ambient temperature and weather, and the demographics of the population also have effects; for example, the early studies from China show that older men have a higher chance of getting infected — though we don’t know why.
So what’s the R0 value for COVID-19 in the U.S.? We don’t know. That’s largely because up until only a few days ago, we have only been testing people in the United States who present with the most serious symptoms of COVID-19 and who had traveled to China or interacted with a known carrier. In mid to late January, the CDC had developed a test for its own lab (and health centers could send samples there to be tested), and they were working on test kits to be sent out to labs across the country starting with the 100 public labs (they are relying on the commercial sector to develop tests for hospitals and primary care facilities). And in early February they began sending those test kits out — but it was soon discovered that the test kits were faulty. That was mistake #1: according to reports coming out now, the CDC’s test was ambitious: the kit had a specific test for COVID-19, plus a second test for a broad set of other coronaviruses. But the reagent used in the second test didn’t work, and labs were unable to verify the test kits as accurate when they received them. Mistake #2 was that the CDC and FDA, instead of certifying the kits for just the COVID-19 test, told the labs to wait for a fixed reagent. So for nearly all of the month of February, the only lab testing for COVID-19 was CDC’s own, which required shipping samples to them and waiting for the results. The CDC wanted not only to enable the 100 public labs and other health institutions to be running their own tests, but also to mobilize the existing network of public health organizations that test and gather data on the spread of influenza every year to supplement their testing with the COVID-19 test so that they could detect whether it was spreading quietly in communities through mild cases. Mistake #3 by the CDC was that it could have enlisted the help of the WHO, which had developed its own test that it was shipping out around the world; it chose not to, and has yet to explain why.
Because of the limited testing ability, the CDC recommended testing only for cases presenting serious symptoms and where the person had traveled to China or come in direct contact with someone who had already tested positive for COVID-19. As of last week when it had finally fixed its test kits, the CDC slightly expanded that to persons experiencing serious symptoms of COVID-19 — in particular respiratory distress. So the United States is STILL not doing widespread testing, despite the clear cases of “community spread” that have been documented in the last few days here in the Seattle area and in Oregon and California.
All this is important context to the news reports we are seeing now of new confirmed cases, and sadly deaths, from COVID-19 in the greater Seattle area. COVID-19 did not suddenly become explosively contagious and start spreading last week; it’s been here for weeks already. We’re seeing more cases now because health organizations are finally testing for it. We can work backward and estimate how long it’s been present, in a couple of different ways. In China, the incubation period was about 6 days; after symptoms appeared, it took on average 9.5 days before the more serious cases needed to be moved to the ICU; and of those, it was on average another 7 days before death for those who tragically succumbed to the disease. Assuming those averages are approximately right and transfer over, it means that those in Kirkland who passed away over the weekend were infected at least three weeks ago. Also, a Fred Hutch research team has been examining genetic samples of COVID-19 from patients, knowing that all viruses pick up small mutations as they are reproduced inside their hosts and passed on to others. The mutation rate for coronaviruses is well understood, and based upon the mutations the researchers found, they estimate that COVID-19 has been present in the Seattle area for at least 6 weeks.
And here is mistake #4 by the CDC, and by the Trump administration: they are actively suppressing information on COVID-19 cases, both from the public and from the rest of the medical community. The CDC, as of today, has stopped publishing information on the number of tests completed as the scandal over its mishandling of testing picks up steam. It also has released little to no information about the existing cases of COVID-19 in the United States, including the ones where the patients fully recovered. This has doctors fuming, as it departs from previous precedent and deprives them of critical information about emerging and best practices in diagnosing and treating cases they are dealing with now — or may deal with in large numbers very soon.
In the meantime, there are other things we can learn from China, while continuing to assume that mileage may vary as COVID-19 shows up in other countries. A recent paper summarizing 52 critically ill patients in Wuhan provides important details on what happens with the most serious cases (understanding that the vast majority of cases are mild). They found that while the most common initial symptoms are fever, cough, and labored breathing, the fever often lagged the other symptoms by 2-8 days. They also found that the “fundamental pathophysiology” of when COVID-19 cases turned critical was severe ARDS — fluid in the lungs. Men and older people (i.e. over 65) are more likely to develop ARDS, putting them at greater risk from catching COVID-19. The researchers also found that the more severe cases happened in people with certain other medical issues, such as pre-existing ARDS, kidney injuries, cardiac injuries and cerebrovascular disease (such as a stroke), but not generally cardiovascular disease or for smokers.
There has been a lot of public discussion of the mortality rate of COVID-19 based upon what happened in China where around 2% of those infected died. That has become the oft-quoted expectation for other parts of the world too, but that is based on several poor assumptions. First, the mortality rate in China varied significantly by age, from 0% for children under 10 to over 14% for those over 80. And, as we have already discussed, some pre-existing medical conditions lead to worse outcomes for COVID-19 patients. Since those underlying demographics are different across countries — and communities — the mortality rate will vary as well.
Another critical point: here in Seattle we have a handful of confirmed cases, and now six deaths. That seems like a very high mortality rate. But remember that there has been almost no widespread testing, so we don’t have any actual idea how many cases there are here (and what percentage of the have died). And nearly all of the deaths over the weekend were related to one long-term care facility in Kirkland, a hotspot of community spread that not only doesn’t represent the broader demographics of the community but is perhaps worst-case for generating serious cases given the research from China. At this point we should be drawing no conclusions about the mortality rate for COVID-19 in Seattle or more broadly in the United States. We simply don’t have the data that would tell us.
Today there is no vaccine to protect against COVID-19, and no proven effective treatments beyond basic support and hoping the patient recovers on their own. But healthcare professionals are working on both. That is important context for where we are in dealing with COVID-19. The virus has been here for at least three weeks and probably more; it is spreading through the community, and it will continue to do so. Most people who catch it will have mild flu-like symptoms; some will get more ill, and sadly some of those will die. If the R0 estimates from China prove valid here as well, we won’t be able to stop the virus; we will just slow down its inevitable march. Geographically it will be everywhere, though only a fraction of the population will catch it; as a point of comparison, the CDC estimates that only about 8% of the U.S. population catches seasonal influenza in a typical year, and the R0 for influenza seems to be in the same range as COVID-19. But slowing it down is important: we are collectively stalling for time until vaccines and treatments can be developed. That helps us and our families, but it also helps to protect those in our communities who are at higher risk of contracting the virus — and who will likely have a more serious reaction.
We should all be doing the following things to fight back against COVID-19:
- Wash your hands frequently, and well. Wash them for 20-30 seconds using soap and warm water.
- Cover your coughs and sneezes, preferably with your arm or elbow, or a tissue, rather than your hands.
- If you are sick, stay home from work or school. Fortunately Washington state has a paid sick time law, which also prohibits retaliation.
- Contact your doctor if you have “flu-like symptoms”: fever, a substantial serious cough, difficulty breathing, muscle aches. You don’t necessarily need to show ALL of these symptoms to warrant calling your doctor. If you think you’re sick, call first before heading to the doctor’s office.
- If you feel that you are too sick to go to a doctor, contact the home assessment team at Harborview Medical Center, which can arrange to visit you at home and assess your condition.
- Look for further guidance from your doctor, Seattle-King County Public Health, and the CDC.
And here are things you should NOT be doing:
- Don’t panic. We should all be more careful, and practice better hygiene. If we are in a high-risk group, we should be even more careful. But there is no evidence that this is — or will be — a major public health disaster.
- Don’t panic-buy supplies. The supply of food and other necessities to your local grocery store has not been interrupted, and likely won’t be. You should have enough food (and other essentials, such as prescription meds and the other over-the-counter meds you like to take when you get sick) so that if you get sick you can just stay at home for a few days; you don’t need to turn into a survivor and stock up on weeks or months of provisions.
- Don’t buy up 95 masks. They are helpful for people who are infected to prevent them from infecting others, but wearing one has not shown to be effective in preventing you from becoming infected. In the meantime, they are become more difficult to procure for the people who really need them now — including medical professionals.
- Don’t avoid going out to lunch or dinner, unless you’re sick or in a high-risk group. At this point it’s believed that the virus has similar contagion characteristics to other coronaviruses and to influenza: it can only survive outside the body for short periods of time in water droplets or on surfaces. You can pass it on by coughing or sneezing on someone, through touch, or in some cases on surfaces. There is no evidence it’s food-borne, so as long as you’re eating at a clean restaurant where the staff are healthy, you should be just fine; the risk of catching COVID-19 at a restaurant is about the same as catching the flu there. Restaurants need our business year-round; if we want them there in the summer, we need to patronize them now.
- Don’t stop drinking Corona beer. Apparently Corona sales have dropped through the floor in the past few weeks. That doesn’t mean you should start drinking it if you weren’t already; just don’t use the virus as justification for a switch.
- Don’t be racist. Yes, COVID-19 first appeared in China, but people of Asian descent in the United States are no more likely to be COVID-19 carriers than anyone else you meet on the street or at work.
At some point, we may get guidance to start taking more drastic measures. There have already been a couple of instances of closing schools for 1-2 days after someone at the school tested positive for COVID-19; however, that’s not something that scales up, so once there is a steady flow of students who have tested positive, school officials will need to decide whether to treat it like a major illness outbreak (like measles) and close the school for weeks, or to keep the school open, practice good hygiene and ride it out.
We may also be told at some point to start practicing “social distancing” — stop shaking hands when we meet people, and generally keeping a distance of about 6 feet away from others. To that end, large events may get cancelled or postponed: sports, concerts, theater performances, etc. There may also be recommendations on public transit (though buses and trains are being cleaned frequently now), and on air travel.
Colleges and some businesses are also looking at how to let people work and take classes remotely, to avoid large gatherings in small places.
But we’re not there yet. Remember, we’re not seeing a sudden explosion of new infections; we’re seeing a sudden explosion of data because they are just starting to test people for COVID-19. In the coming weeks as we learn more, elected and public health officials will be giving us updated guidance on how best to control the spread of the virus as we wait for better solutions.
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