Wednesday COVID-19 Briefing

Special Note: I’m away this weekend. The next briefing will be next Wednesday. Send me your COVID-19 questions while I am gone.


Top news, reports and insights for today:

  1. Curated headline summaries for Wednesday:
  • Two recent peer-reviewed studies show there has been a “sharp drop” in the mortality rate among patients hospitalized for COVID-19 and those with pre-existing conditions. The main drivers of this decline appear to be standardized treatment protocols, better control of blood clots, and because mask wearing means people are acquiring less severe infections. Although good news, the CDC says hospitalized COVID-19 patients are still more than 5-times more likely to die than those hospitalized with influenza (Axios)
  • New survey shows that while COVID-19 test results are coming back faster than in the Spring, results are still too slow to optimize contact tracing and infection control procedures (2.7 days on average in September). Half of those who test positive are never contacted about who they might have exposed (NPR)
  • The World Health Organization (WHO) releases preliminary results of the largest randomized clinical trial in the world to study existing drugs for treating COVID-19 in the hospital. The results indicate that remdesivir, hydroxychloroquine, lopinavir/ritonavir and interferon regimens appeared to have little or no effect on 28-day mortality or the in-hospital course of COVID-19 among hospitalized patients. Many are now criticizing the details and design of the trial (WHO News)
  • Residents were tested in skilled nursing facilities (SNFs) in 20 states. Of those found to be infected, 41% had no symptoms (asymptomatic) and another 19% were presymptomatic (developed symptoms after testing). Many believe nursing home residents, being more vulnerable, are much less likely to have asymptomatic infections. This study shows that is wrong and tells us why screening nursing homes for COVID-19 is so important (JAMA Internal Medicine)
  • A study not yet peer reviewed looked at the impact of temperature and humidity on the viability of SARS-CoV-2 virus indoors. The virus survives better when it is colder and humidity is extreme. Compared to the heat of summer, the virus remains viable on a plastic surface more than 10 times longer when it is cold and dry. If confirmed, this adds to concerns that infections will significantly intensify in the winter (BIORXIV)
  1. U.S. daily cases continue to surge; 7 states remain “white hot”. Putting recent case surges into context requires juggling at least 4 other balls
      Good disease detectives must simultaneously consider multiple intersecting clues to understand the dynamics at play. It’s a scientific case of keeping multiple balls in the air (I do love juggling analogies). As the epidemic moves along, keeping a cool head gets harder, not easier. Today’s briefing is a case in point. Consider our old friend, Figure A, which shows continuing surges in cases. We aren’t there yet, but daily cases are heading back to the previous swell in July; the 7-day moving average peeks over the 55,000 mark. These numbers are alarming, especially in a handful of states where new daily cases are over 40 per 100,000 a day (Figure B): Idaho (43), Montana (60), Kansas (44), North Dakota (an astonishing 102), Nebraska (43), South Dakota (77) and Wisconsin (57). The states currently under control (<5 cases per day per 100K) are now down to three (Maryland, Maine and Vermont).
     To put these numbers into context however, a good disease detective pays equal attention to the other balls aloft. Here are two really important figures that help us to make sense of this. Figure C is my modification of a graph from the COVID Tracking Project showing two weekly average curves: one for daily cases (red) and one for currently hospitalized (blue). In my opinion, there are three distinct epochs, or periods in this figure, shown here as green boxes I added. Period I from late March through mid-June was characterized by twice as many people in the hospital as there were lab-confirmed cases. How could there be more in hospital than cases? Some of this is lag time. But mostly it is because we were just testing people who came to the hospital with symptoms and were already sick. During this period, there were probably 50-500 times more actual cases than we knew about. Our testing fraction was really low given the imaturity of the testing regime. During Period II from July 1 till the end of August, daily cases and hospitalized patients were tracking closely. Our testing had broadened over the summer and we were capturing a bigger fraction of total cases. The current phase (Period III) started in the middle of September, and saw, for the first time, daily cases exceed hospitalizations. This shows our testing is maturing further. The main point here is to notice that during Period II, the case curve is now rising faster than the number of hospitalized patients.
     To make further sense of this, we have to consider two more flying balls. The first is depicted in Figure D showing daily U.S. tests. On top of the CTP data I have imposed the same three “periods”. During Period I, testing ramped up steadily from 100,000 a day to half a million. While that was real progress, we never got close to the critical mass needed to shed light on population dynamics. During Period II, testing rose in July but flattened in August and actually went down for a few weeks. Who could blame us for letting our foot off the gas pedal during the summer when so many people thought we had rounded a corner. Thankfully, we have reversed that trend in Period III. Since September 11, we have boosted testing from 750,000 a day to over a million. When combined with stability in daily deaths (the final ball we are juggling) the overall rise in cases is neither surprising or as profoundly concerning on it’s own as would be the case 6 months ago.
    The bottom line: U.S. cases are on the rise again, spiking especially in seven hot spot states in the Midwest and West. The rise in cases must be seen in the context of rising testing, hospitalization rates, test positivity and mortality. Increasingly, the key barometers of progress against this disease will be the latter metrics. Thankfully deaths remain stable, test positivity is only nudging higher and hospitalizations are increasing in hot spot states, but not as fast as cases. Tracking an epidemic is about juggling, not staring too hard at any one ball.
Figure A
Figure B
Figure C: Daily cases and currently hospitalized in the U.S. (COVID Tracking Project) and three hypothesized periods (green boxes)
Figure D: Daily testing in the U.S. (COVID Tracking Project) and three hypothesized periods (green boxes)
  1. The holidays are coming and it’s time to plan. Is it a good idea to have a family gathering?
     If you are like me, you are thinking about the holidays and wondering if and how to have family gatherings. I don’t have the answer for you, but as I think through things for myself, I can tell you what factors are on my mind. As an epidemiologist and disease detective, I look at family gatherings as risky situations during an epidemic. Infectious disease transmission is all about mixing. How does the virus get from transmitters to those who are susceptible? The purpose of infection control measures is to limit mixing. Social gatherings like weddings, funerals, graduations, and holiday gatherings, involve an especially hazardous kind of mixing because many bubbles interact, exchange pathogenic companions, and then disperse, bringing newly acquired organisms back home. Family gatherings tend to be multi-generational, mixing older or more vulnerable family and friends with young people who themselves do more mixing (have bigger bubbles) and think themselves low risk.
     It is increasingly clear that the recent surge in U.S. cases is being driven by infections in young people that spill over to more vulnerable groups. This, in turn, is driven by students returning to school, pandemic fatigue, and rebellion and distrust among those who perceive themselves to be low risk. A series of reports in the CDC’s MMWR are worth highlighting here. The first comes from an October 16 report looking at changes in test positivity in 767 hot spot U.S. counties in June and July. Overall, it shows the biggest jump in the percentage of tests that were positive before and after the hot spot was detected among the 18-24 year old age group (Figure E). More so than other age groups, test positivity rose in young people prior to the onset hot spots where older people got sick and died. The jump in TPR was much more pronounced in the Midwest and South, the regions that have been on fire in recent months (Figure F). Together, these data strengthen the case that young people are driving outbreaks even though they themselves are not as likely to get severely ill or die. It also shows the social distancing message is not getting through in the Midwest and South.
     The second MMRW from October 6 interviewed young adults in July after a series of outbreaks in Winnebago County Wisconsin, now a super hot spot state. Researchers found young people feel peer pressure not to wear masks and get “odd looks” if they do. Most perceive themselves to be low risk for severe disease but worry about passing the disease to loved ones. Most have received confusing messages and misinformation about the virus. Young people say they wear masks in public or at work but also admit to attending social gatherings with peers where they feel pressure not to mask and distance.
     A third MMWR report from October 9 is about a 3-week family gathering this summer during which a 13 year old girl (who was previously infected but had a negative test) passed the disease to 11 other family members (Figure G). Take home message from this case: 1) a family gathering attended by a child with a runny nose led to 11 secondary infections and an unknown number of tertiary infections once those people returned home. 2) All the secondary infections happened in those who shared the same house and did not wear masks. Other family members who stayed outside and wore masks remained uninfected. 3) The index case came to the event with a negative test that was wrong. This highlights the importance of following up antigen tests with PCR tests and why a 14-day quarantine period is critical for those who have symptoms.
    The bottom line: a series of MMWR reports shed further light on how young people are driving the epidemic. Family gatherings are inherently risky if they connect many bubbles across generations. If you are planning holiday family gatherings, wearing masks, sanitation procedures, good ventilation and staying outdoors will lower the risk. Ultimately, keeping our distance is inherently harder with loved ones when celebrating special occasions.
Figure D: From https://www.cdc.gov/mmwr/volumes/69/wr/mm6941e1.htm#F1_down
Figure E: From MMWR, https://www.cdc.gov/mmwr/volumes/69/wr/mm6941e1.htm#F1_down
Figure F: MMWR: https://www.cdc.gov/mmwr/volumes/69/wr/mm6940e2.htm
  1. Quirky Qorner: Keeping score on the American spirit: Wienermobile 1, Coronavirus pandemic 0!
     I am not sure I would call this a “feel good” story given how I feel after eating them, but let’s put one in the win column for the American spirit. Oscar Mayer has been sending a fleet of Wienermobiles across the country promoting their meat tubes since 1987. Actually, thanks to a delicious story I found in the New York Times, the mobile meal actually began rolling down the streets of Chicago in 1936 during another time of national calamity: the Great Depression. When the pandemic exploded, the company was forced to rest their rambling red-hots for the first time in 33 years. In a testament to the resilience of the American spirit, the company announced in August they would send their fleet of 6 mobile mouth pleasers back on the roads, albeit with some additional safety modifications. Over 7,000 people applied for twelve positions piloting the mechanical meat mobiles. Other fun facts about the “Weenie-bagos”: a) no, they don’t actually serve hot dogs, and b) no, there is no bathroom in the “back” of the bun. Groan!
From: https://www.nytimes.com/2020/10/20/style/inside-oscar-mayer-wienermobile.html
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