Behaviors National changes Texas update

National (U.S.) Update

Your national (U.S.) update as of Feb 3 at 8:00PM CST

Cases… continue to plummet. There’s no doubt that the 2020 holiday season caused a surge in cases. Which is consistent with what we saw on Memorial Day and July 4. The impact that human behavior, like the 2020 holiday season, has on human life is really quite fascinating. Anyways, our 7-day average is now the same as it was on November 12. Today, 42 states have a decreasing 7-day average of cases and 8 states are plateauing. Only Texas has an increasing 7-day case rate (11%).

Testing…is continuing to plateau, which isn’t necessarily bad. Especially if cases continue to decrease. Because this means that test positivity rate will be decreasing. Which is fantastic. We want TPR<10% (<5% is ideal) to get a handle on transmission.

Hospitalizations….are tanking too. Hospitalization trends follow case trends, so this makes sense. Hospitalizations in 41 states are decreasing, 9 states are plateauing, and 1 states is increasing (Vermont=15%). This is also fantastic news. But, remember, decreasing is relative. They are decreasing from the highest peak we’ve every experienced. Today, 91,440 people were on hospital beds for COVID19. This is still higher than the peak in April (59,779 hospitalizations) and July (59,718 hospitalizations).

Deaths…are increasing but significantly losing momentum. In other words, we should see our peak here soon (if it wasn’t today or yesterday). 27 states have decreasing deaths, 15 states are plateauing, and 9 states are increasing. The highest increase in deaths is Iowa, closely followed by South Carolina. Today 3,685 souls succumbed to COVID19. In one day. We were predicting 500,000 deaths by mid-February. This may be end of February now. TBD.

Vaccinations…are slowly (but surely) starting to gain speed and exponentially increase. Which is huge. We (the U.S.) are administering 9.71 doses per 100 people. In the last week, an average of 1.34 million doses per day were administered. Alaska leads with 13.4 doses administered per 100 people. This is followed by West Virginia (11 per 100) and New Mexico (10.5 per 100). Idaho, you’re last, with administering 6.0 doses per 100 people. (Texas you’re close to the bottom too, at 7.2 per 100 people).

Variants...are gaining speed.-B.1.1.7 variant: Has popped up in 541 Americans across 33 states (Florida has, by far, the most people followed by CA). -B.1.351 variant: Detected in 3 Americans in 2 states-P.1: Detected in 2 Americans in 1 state

We are, quite literally, in a race: vaccination rate vs. variant transmission rate. Hopefully we win before mid-March hits.

Love, YLE

Case data: COVID tracking project

Vaccination data:

More vaccination data:

Variant data:

Behaviors National changes Side Effects Variant

Quick update…

Several COVID19 developments popped up in the past 24 hours. Here’s my attempt to keep you up to speed…

-Data are stabilizing and we are starting to see the impact of the holidays. For the second day in a row the United States had more than 4,000 deaths per DAY. This is about what we, epidemiologists, expected because 22 days ago there were 239,795 daily cases. Today, 131,889 people are hospitalized and 7,900 people are on ventilators. We are hitting new records across every metric.

-There is NO scientific evidence of a new US variant (this is different than the UK or SA variant). This misinformation stemmed from a document circulated yesterday that speculated the increase in winter cases (compare to summer) must be due to a new variant. In Nov and Dec, 5,700 samples were collected and analyzed by the CDC and there is no evidence of this. However, the more this thing spreads, the more opportunity this virus has to mutate. Can we agree to start wearing masks and stop seeing friends?

-The Biden administration announced that they will not withhold the second dose. This is still a highly debated topic in public health (maybe the most debated since the pandemic began). My scientific opinion: Supply isn’t our issue right now; capacity and logistics are. As of this morning 22.1 million vaccines have been sent off; only 6.68 million Americans received their first dose. Yes, some of this discrepancy may be due to reporting lags, but this doesn’t explain it all. Our federal priorities should be setting up vaccine surveillance, setting up mass vaccination sites, and clear, consistent communication. Way too many people are in the dark. Now, if we get off the ground from this rocky start, then we can talk about the second dose.

-Every Friday the CDC Vaccine Adverse Event Reporting System (VAERS) is updated. The more people that get vaccinated, the closer we get to the “true” rate of adverse events. 6.68 million doses of the vaccine have been distributed and 3,907 adverse events have been reported to VAERS. The most common symptom is headache, nausea, and pain. 30 people/physicians reported anaphylactic reactions. On Jan 6, CDC published a report describing 21 of these cases in 1.89 million doses. Of which, 71% occurred within 15 minutes of vaccination. There are limitations to VAERS data (which I’ve posted about before).

Okay, I think that’s it for now.

Love, YLE

Data Sources:
Graph 1: Covid Tracking Project
Graph 2: Made by yours truly with VAERS data
Vaccine tracker:
CDC report:

Behaviors Children Daycare Social Distancing

COVID19 infections among kids…

Kids (<18 years) make up of 10% of COVID19 infections in the United States. Because of that, it’s taken a bit more time to have enough infected kids for meaningful analyses (compared to adults). The CDC published an important study Tuesday assessing school, community, and close contact exposures associated with child and adolescent COVID-19 infection.

The study took place from Sept to Nov 2020 in Mississippi. 397 parents of children who recently had a COVID19 test completed a phone survey. They answered questions about symptoms, close contact with a person with known COVID-19, school or child care attendance, and family or community exposures ≤14 days before the COVID test. Then, scientists compared the answers across kids with a COVID19- test to kids with a COVID19+ test. There were a couple things they found…

COVID+ kids were MORE likely to have…

  • Had close contact with a person with known COVID-19. And, this close contact was more likely to be a family member than someone at school
  • Attended gatherings with people outside their home, including social gatherings (weddings, parties, funerals, birthday parties), playdates, or to have had visitors at home

COVID+ kids were LESS likely to have…

  • Consistent mask use by students and staff members inside school or child care facilities

Interestingly, there were essentially no difference between COVID+ and kids going to…

  • Sports events or concerts (18% COVID+ vs. 20% COVID- kids)
  • In-person school or child care (62% COVID+ vs. 68% COVID-)
  • Religious services (13% COVID+ vs. 18% COVID-)
  • Restaurants (20% COVID+ vs. 16% COVID-)
  • Travel with others (5% COVID+ vs. 3% COVID-)
  • Household member working in health care (24% COVID+ vs. 21% COVID-)

Before I get the comments, here are a few important notes…

1. This doesn’t mean, for example, you have carte blanche to go to indoor restaurants. This is a study of kids. This does not mean you, as a parent, won’t get it or spread it

2. No, there is no data on teachers or staff. Yes, that would be a needed analysis. I’m sure it’s coming.

3. Yes, masks work. This study showed that adults wearing masks helps kids, especially within schools and child care center. If you need more evidence, check out my previous post (

4. Opening schools is a bit more complex than kids getting infected. Kids are less likely to get sick (and not go get a test), but they harbor the disease and have the potential to spread it to others. Unfortunately, we still don’t know the rate of transmission from kids to adults.

Finally, I would like to take a moment to recognize how quickly and hard these scientists had to have worked to get this information out to the public. Data collection ended November 5, 2020. That means, within a MONTH, they cleaned the data, analyzed the data, came to meaningful conclusions, wrote up the science, sent it up the CDC ranks for approval, responded to feedback, and submitted for publishing. For the record, this typically takes 1-2 YEARS. Absolutely incredible.

Love, YLE

Data Source: Hobbs CV, Martin LM, Kim SS, et al. Factors Associated with Positive SARS-CoV-2 Test Results in Outpatient Health Facilities and Emergency Departments Among Children and Adolescents Aged <18 Years — Mississippi, September–November 2020. MMWR Morb Mortal Wkly Rep 2020;69:1925-1929. DOI:

Behaviors Social Distancing


…is coming during the highest peak of COVID19 cases (and hospitalizations) the U.S. has ever seen. This holiday’s potential impact on transmission, hospital strain, and mortality cannot be understated.

Here are three published, peer-reviewed case studies that illustrate COVID19 transmission at family gatherings:

•In February 2020, a funeral was held for family in Illinois. The evening before the funeral, the index case (with mild cold-like symptoms) shared a takeout meal, eaten from common serving dishes, with two family members of the decedent at their home. At the meal, which lasted approximately 3 hours, and the funeral, which lasted about 2 hours and involved a shared “potluck-style” meal. The index patient also embraced family members of the decedent and others attending the funeral. Three days after the funeral, the same index case (who was still experiencing symptoms) went to a family birthday party. They embraced each other and shared food during the 3-hour party. Between the funeral and the birthday, 16 family members were infected and 3 died.

• Back in June, a family (two parents, two sons, and one daughter with a stuffy nose) traveled to a vacation home to meet with 15 other relatives. These relatives were from five households from several states whose ages ranged from 9-72. During this vacation, relatives did not wear face masks or practice physical distancing. Another 6 relatives (aunt, uncle, and four cousins) visited a few days later but stayed outdoors and maintained physical distance from the other 15 relatives. What happened? Well the stuffy nose was actually a COVID19 infection. She proceeded to infect 11 other relatives, 2 of which went to the hospital. The 6 relatives that stayed outdoors and physically distanced did NOT get infected.

• In January, a Chinese elderly couple celebrated the Chinese Spring Festival in public. Neither had symptoms when, a few days later, the couple’s daughter, son-in-law, and 2 grandchildren visited them. A few days after this visit, the daughter went to have dinner with another family unit. The grandma (who went to the Chinese Spring Festival) was infected with COVID19 without knowing it. She directly or indirectly infect all (but one) family members. One, of which, was admitted to the ICU.

We are all tired of this disease. But I hope these examples show you how easily this is spread, even if you aren’t experiencing symptoms. With all the good news this week (vaccine, new task force, new antibody treatment) we know there’s light at the end of the tunnel. We will be through these dark times. But, we aren’t at the end of the tunnel yet.

It’s time to re-evaluate your Thanksgiving plans. This may mean reorganizing (go to a park instead of a home), having conversations with family/friends to set expectations (yes this may be awkward), cancelling plane tickets (this will avoid spreading clusters), and cancelling plans (stick with immediate family). It’s hard. And heartbreaking. But it’s the reality of the situation.

Love, YLE

Data Sources:

Funeral/Birthday party:


Chinese family:

More from the CDC:…/daily…/holidays/thanksgiving.html



And we have the scientific evidence to back it up. In fact, we have over 85 peer reviewed, scientific studies. 35 have been published in 2020 alone.

What do these studies say? Mask use…

* …is associated with a decline in the daily COVID-19 growth rate

* … stopped more than 200,000 COVID-19 cases in the US by May 22, 2020

* …In countries with positive mask norms or government policies, per-capita mortality increased on average by just 15.8% each week, as compared with 62.1% each week in remaining countries

* … decreases R(t) below 1, leading to the mitigation of epidemic spread.

* …among index cases in households, decreases secondary transmission by 79%* …does NOT reduce the amount of oxygen you’re receiving

* …reduces transmission of infected droplets in both laboratory and clinical contexts

* …prevents transmission, particularly in high risk settings like healthcare, planes, and hair salons

* …reduces the dose of virus a wearer might receive, resulting in infections that are milder or even asymptomatic

* …drives the wearer and those around them to adhere better to other measures, such as social distancing, reminding people of shared responsibility.

And my small list just touches the surface of evidence. Since July, mask use in the United States has been at a steady 60%. But we need this to increase.

Studies show that if…

* ….80% of the population wore masks, this would do more to reduce COVID-19 spread than a strict lockdown

* … 95% of population wore masks, we could have avoided 33,000 deaths in the US (as of October 1)

I’m not entirely sure why the efficacy of mask use is still up for discussion. But, nonetheless, this simple, low-cost intervention has the potential for a large impact. Concurrently, it’s important to recognize that mask wearing it’s not the cure all. It has to be combined with other public health efforts for ultimate success. (Many epidemiologists use swiss cheese to illustrate).

This virus is smart. We have to be smarter.

Love, YLE

Data Sources: Here are 70 studies, but this was last updated July 3. Since there have been quite a few more including the most recent here: Graph comes from the Institute for Health Metrics and Evaluation (IHME)…an independent global health research center at the University of Washington:…

Behaviors National changes

US Presidential Rallies

The close of election season is upon us. A new study found that this is particularly good news for epidemiologists, as U.S. presidential rallies were associated with an increase in COVID19 cases.

In a recent study, scientists looked at the change in COVID19 cases across 20 counties that hosted rallies from August to September 2020. They compared the change in COVID19 cases to US counties that did not host a rally.

What did they find?

-On average, COVID19 increased in host counties by 50% compared to non-host counties

-Peak increase was 5 days post-rally (which is consistent with the time interval from infection to detection)

-The county with the highest COVID19 increase was Lackawanna PA (a 3.8 fold increase in COVID19). Before the rally, this county had the 2nd lowest number of COVID19 cases per 100,000.

-2 out of the 20 counties (Saginaw MI and Yuma AZ) had a DECREASE in county-level COVID19 cases

-The county with an indoor gathering had an increase, but the relative increase in cases was higher in 9 outdoor counties.

Translation: Mass gatherings outdoors OR in counties with low incidence did not entirely prevent the spread of COVID19. Additional public health measures, ensuring multiple layers of protection, must be taken.

Love, YLE

Data Source:…/2020.10.22.20184630v1.full.pdf

Behaviors Deaths

Superspreading Events (SSE)…

…are fascinating to me. Maybe because they are so difficult to predict, and therefore, challenging to prevent. They are also not new. In 1997, scientists estimated that 20% of the population contributes to 80% of transmission of infectious diseases. This has been seen with TB, measles, SARS, MERS, and Ebola. For example, during SARS, one hotel guest caused 4 national and international clusters. For Ebola, 3% of cases were responsible for 61% of infections.

Several SSEs have been described during the COVID19 pandemic (see my previous posts). Last month, there was another one at a Maine wedding. This wedding took place in Millinocket, Maine, a rural town with a population of 4,300. Before the wedding, there were NO cases of COVID19 in the town. The wedding turned into the state’s largest outbreak.

What happened? See figure. Briefly,

  • 65 people attended the wedding; 56 caught COVID19 (86% attack rate)
  • This has now spread to 270 people over 500 miles
  • 8 people have died, of which, none attended the wedding

Small events can add up to a lot. In fact, the “smallness” can cause a false sense of security. What does matter is… 1) how infectious that index case is; 2) how many close contacts the index case had at the event; 3) over what time period; 4) and where (indoor vs. outdoor).

A psychologist at Princeton recently stated, “When you live in a war zone, after a while, everyday risk becomes baseline. Our neurons are wired in such a way that we only respond to change. People have gotten used to being in this new state of danger, adapting to it, and therefore have not taken enough precaution anymore”. The wedding was inside. No one wore masks. No one social distanced. It exceeded Maine’s 50-person limit. This is yet another example of pandemic fatigue. Also, an example of the importance of coordinated and timely contract tracing, testing, and quarantining during a pandemic. Speed is essential.

Love, YLE

Data Sources:


20/80 rule:


Maine CDC briefing:


COVID19 and flying

Flying and COVID19.

If you’re anything like me, you’re dying to get away for the holidays this Fall. But traveling, in terms of COVID19, comes with risk. And, like anything, each one of us have to weigh the pros and cons of this risk.

Yesterday, the CDC published two case studies demonstrating COVID19 spread on airplanes. Both of the flights were in March (so “early” on the pandemic), but shows that, if we don’t do anything, attack rate of COVID19 on a plane is high. What did they find?

  • On a 10-hour flight from London to Vietnam (March 2), a symptomatic passenger (Female, 27 years old) was sitting in business class. 16 other people (out of 217 passengers and crew) were infected during the flight. The attack rate was 62% among people in business class. People sitting closer to the index case (2 meters) were more likely to get infected than sitting more than 2 meters from the index case.
  • On a 15-hour flight from Boston to Hong Kong (March 10), two index cases (from North America) infected two others on the flight (from China). This is now known because the scientists used genetics. Because this study was retrospective, they didn’t conduct testing on all passengers, so we don’t know the attack rate. But we do know it was transmitted on the plane.

It’s important to mention that a previous scientific article found no spread on a plane…

  • On a 15-hour flight from Wuhuan to Toronto (Jan 22), there was a symptomatic index case on the flight with approximately 350 passengers on board. This index case also happens to be the first case in Canada. After the flight, close contacts (within 2 meters of passenger) were instructed to monitor symptoms daily and contact public health officials for 14 days. 6 passengers were symptomatic, but all tested negative for COVID19. This study put considerable faith on the limited testing (compared to the first CDC article), and we don’t know the true attack rate. But if there was spread, it likely caused asymptomatic or mild infections.

Air travel requires not just traveling in a plane, but also spending time in security lines and terminals and getting to and from the airport. The CDC states that “once on the plane, most viruses and germs do not spread easily because of how air circulates and is filtered on airplanes. However, social distancing is difficult on crowd flights, sitting within 6 feet of others, sometimes for hours, may increase your risk of getting COVID19”.

If you choose to air travel, check out the company website first. Company compliance and adherence to public health recommendations lay on a spectrum. Before you buy tickets, make sure they are:

  • -Requiring people to wear a mask
  • -Promoting social distancing
  • -Using online or contactless reservations and check-in
  • -Enhanced cleaning procedures

Wearing a mask on a flight is a pain. But it it’s just that…a pain. It can significantly reduce your risk and the risk of everyone else on flight so we can all enjoy the holidays.

Love, YLE

Data sources:

Vietnam flight:

Hong Kong flight:

Canada flight:

Behaviors National changes

Flu and COVID19 and Fall

There are two hypotheses regarding what will happen this Fall: 1) flu season will be, essentially, non-existent because people are wearing masks and social distancing (due to COVID19); or 2) the combination of flu and COVID19 epidemics will add strains to the healthcare system that we’ve never seen before.

The US is lucky though because flu seasons hits the Southern Hemisphere before hitting us. Their flu seasons is from June to September (peaking in August). Every year, we use this to our advantage to predict our flu season.

So, now that their flu season is over, what did it look like in the Southern Hemisphere (and specifically Australia, Chile, and South Africa)?

  • VERY little flu activity. In 2020, Australia, Chile and South Africa had 0.06% positive flu tests (51 out of 83,307). For a comparison, from 2017-2019, they had 13.7% positive flu tests (24,512 out of 178,690).

We are seeing similar trends during the non-flu season in the U.S.…

  • Typically, during the non-season we have about 1-2% of positive flu tests. This year we have 0.2% positive flu tests.

So, it LOOKS like hypothesis #1 is what we can expect this Fall. Thanks to the community mitigation measures to reduce COVID19, we will also reduce flu transmission. We have to keep it up though (and go get your flu shots!) or hypothesis #2 will take over.

Love, YLE

Data Source: Olsen SJ, Azziz-Baumgartner E, Budd AP, et al. Decreased Influenza Activity During the COVID-19 Pandemic — United States, Australia, Chile, and South Africa, 2020. MMWR Morb Mortal Wkly Rep 2020;69:1305–1309. DOI: icon

Behaviors National changes

Need another reason to wear a mask?

We already know a few things…

  • If you wear a mask, you’re protecting those around you (whether you know it or not). A mask reduces the distance and the number of droplets when talking, sneezing, or coughing. With 40% of cases being asymptomatic, universal mask wearing is especially important because you may be spreading the disease even if you feel great
  • A mask can protect the wearer by blocking particles from coming into the nose and mouth. For example, after universal mask wearing was implemented in Boston hospitals, infections decreased among health care workers.

The New England Journal of Medicine recently published another possible reason to wear a mask. This is NOT peer-reviewed science, it is an educated guess (hypothesis). Meaning the scientists used previous studies to make this guess. However, for the TOP medical journal (and I mean TOP) to publish a hypothesis means there is legitimate weight behind this guess.

What are they guessing? Universal mask wearing reduces the severity of COVID19 among those who do wear a mask.

Why? In epi, there is this concept called “dose-response”. For COVID19, this means the more virus particles you are exposed to, the more severe your symptoms/outcomes will be. And vice versa. So, if someone sneezes directly on your face you will get much sicker than touching COVID19 on a surface.

SOO, their thought process is that if you wear a mask, you filter out a lot of virus particles (dependent on mask type), and then your disease/symptoms will be less severe. In fact, this allows more people to get the asymptomatic disease MORE (compared to symptomatic disease). This is good because even among asymptomatic and mild cases of COVID19 you can develop antibodies. We get closer to herd immunity.

We have seen this, anecdotally, in a few instances:

  • Argentinian cruise ship, where people were provided masks, asymptomatic infection was 81% (compared to 20% in earlier cruise ship investigations)
  • US food processing plants, people were provided with masks each day, 95% were asymptomatic and 5% experienced mild-to-moderate symptoms during recent outbreaks
  • Countries with population-wide masking have fared beer in terms of COVID19 rates and deaths
  • Syrian hamster models (i.e. not humans) this hypothesis has shown to work

This is an educated guess. Now, other epidemiologists will (hopefully) test this guess to see if it is true. IF this is hypothesis is true, it’s a game changer, especially in the US while we wait for a vaccine with less-than-ideal testing and response.

Love, YLE

Data sources:

This guess:

Masks work:;;

Hamster study: