Post #1513: William and Mary, last COVID-19 update for the semester


The uptick in new COVID-19 cases at William and Mary that started a few weeks back appears to be ending.   But, because students have been/continue to leave the campus at the end of the semester, that’s not crystal clear.  But the current week continues the downward trend seen last week.

Source:  Calculated from William and Mary COVID-19 dashboard, accessed 5-16-2022.

You can see that the infection rate for the comparable (age 18-24) Virginia population rose last week, in line with the overall increase in the official count of new infections in Virginia.

For sure, this is the last usable reading for the semester. Everyone but the Seniors has gone home at this point.

In truth, this is likely to be my last update ever.  My daughter graduates this year, and I no longer have a reason to track after that.  Let’s hope that by that time fall semester rolls around, the new case rates are so low that nobody need to bother to track it.

Post #1506: COVID-19 at William and Mary, no better, no worse.


Source:  Calculated from William and Mary COVID-19 dashboard, accessed 5/9/2022

William and Mary updated their COVID-19 dashboard last night.  The most recent new infection rate in the student body is about 100 per 100K population per day.  Roughly speaking, the uptick that started a few weeks back is not getting any worse.  But neither has it disappeared.

I looked at last weeks numbers and didn’t get a booster shot.  I figured I’d wait to see if this weeks numbers resulted in any greater clarity.  No such luck.

So now, push comes to shove on the question of getting a vaccine booster before attending graduation ceremonies, because those are now less than two weeks away.  We’re about at the time limit, as it takes some time for antibodies to build after a booster shot.

To boost or not to boost?

Time for some guesswork calculation.

First, I want to guess the likelihood that I’m going to be in the same room as somebody who is infectious with COVID-19.  At that stage, that’s not the odds of getting infected.  (Being in the same room does not guarantee infection).  It’s just a way to start getting a handle on the riskiness of the situation.

For that, I need two figures:  How many people are involved, and what fraction of them are likely to have an active COVID-19 infection?

I expect to attend three small indoor graduation ceremonies, with an average of maybe 100 student and 200 family members each.  Call that a total cumulative crowd of 900 people with whom I’m be sharing an indoor space. 

Currently, Virginia is averaging 27 new cases per 100K population per day.  If we stick to our current trend, that’ll be around 50, two weeks from now.  Taking the weighted average of that (for the family members) and 100 new cases per 100K (for the students in attendance), I come up with an expected average of 67 known new cases per 100K population per day.

You have to multiply the new-case rate that by two factors — one to account for cases that are not officially reported, and one to account for the number of days an infected person typically remains in circulation and capable of infecting others.  At various times, I’ve guessed estimates for both of those.

At the low end, I’d multiply the current new-case rate by six.  That’s a factor of two, to account for cases not counted in the official statistics, and an average of three days walking around in an infectious state (combining both symptomatic cases and asymptomatic cases).  But I could easily see a factor of nine, if you figure there are three true cases, now, for every one that gets officially diagnosed and reported.

So, take either a nine-fold rule or a six-fold rule as a reasonable way to estimate the number of actively infectious individuals in a crowd, based on the current official daily new case rate figures.

Now I do a lookup on a chart I worked up a few months ago.  Once you accept either a nine-fold or six-fold multiplier above, the rest is just math.  So the chart itself is nothing but a bunch of arithmetic, tabulated.

Without belaboring the assumptions behind the “N-fold rule”, I think it’s a foregone conclusion that I’m going to end up in the same room as somebody who has an active COVID-19 infection. 

I don’t think that’s a surprise, given that this boils down to hanging out in a crowd of about 1000 people in the middle of a modest new wave of COVID-19 cases.

How may people would I expect?  Maybe four or five actively infectious individuals, total, in the crowds I’ll be part of two weeks from now.  Same assumptions, just slightly different math.

Now comes the less-quantifiable part.  What are the odds of being infected, given that?  Let’s say there’s a roughly 0.5 percent chance (4.5 persons out of 900) that any one seat in that room is occupied by an infected individual.  And, in total, I expect to spend about three hours in situations of that type.

Literally the only quantitative analysis I have to go on is a study of Chinese train passengers from early in the pandemic.  This has the multiple disadvantages of being a) train service, and b) the original Wuhan version of COVID, for which the R-nought (basic infectiousness) is at least five times lower than the current strains (BA.2 and BA.2.112.1).

Whatever.  This is the best I’ve got.  This is a study of known infected individuals who took a train trip, and the subsequent infection rates of the people seated around them.  I infer from the writeup that these passengers were not wearing masks.  I’m just going to fuzzy-up the details, and state the following.

On average, for a relatively short exposure, risk in that study was only observed for persons sitting within two rows and two columns of the infected individual.  That means 5 x 5 = 25 seats, less the two occupied by myself and my wife, or 23 strangers sitting within range of me, at each of three one-hour ceremonies.  If, by contrast, W&M leaves every-other-seat empty, then that would mean sitting next to roughly 13 strangers.

Looking at Figure 4 from that study, at the one-hour mark, averaged across all nearby sites, the risk of infection was 0.14 percent per hour, for all those seats.   And, luckily for me, that’s by far highest from the person sitting next to you, on the same row, which will be my wife.

But that was for the Wuhan strain.  There’s no direct way to translate it, but the R-noughts of the current strains are at least five times greater than that.  So, as a rough cut, let me multiply that baseline infection (attack) rate by five, to yield 0.7 percent per hour risk of infection, accounting for the far greater infectiousness of BA.2 and BA.2.12.1 relative to strain B.

Worst case:  When I grind through the numbers, I estimate that if we weren’t vaccinated, and if we didn’t wear masks (the conditions for the Wuhan train study), and W&M does not leave every-other-seat empty, we’d have about a 1-in-400 chance of contracting COVID-19, sometime in the course of three one-hour sessions, given the current new case rates in Virginia and within the W&M student body.

Obviously, that’s a rough cut, but some estimate is better than no estimate.

Now you have to factor in the effects of wearing a properly-fitted N95 mask, and of vaccination and booster.  But you also have to figure that every meal we eat, over that time period, is going to be in a packed restaurant.  And indoor dining is well-established as a relatively high-risk situation for COVID-19 transmission.  If I had to guess, on net, I’d guess that our net risk of all that is at least four-fold smaller than the one-in-400 cited above, due mostly to mask use.  (Per prior post, impact of vaccination on probability of getting any infection is now quite small, due to decline in circulating antibodies over time).

Finally, if we only get one booster, we have to figure out whether or not this is the most risky thing we’re likely to do in the next half-year or so.  If so, might as well use up our one allotted additional booster shot now.  Or, conversely, figure out whether they’ll allow yet a third booster shot this fall, as we get the expected winter wave of flu-and-COVID.


When I put all that in the blender and give it a whirl, the upshot is that my wife and I have made appointments to get our second booster shot this afternoon.  Obviously, YMMV.  We’re in our 60’s and overweight.

Despite the thin veneer of rationality above, really, I think the deciding factor is probably nowhere near as quantitative as the discussion would suggest.  In the end, the less I have to worry about @#$(!@ing COVID-19, the more I can enjoy watching my daughter graduate from college.  And for me, that’s well worth getting my last allotted booster shot before we attend those ceremonies.

Post #1499: W&M COVID uptick continues



Source:  Calculated from W&M COVID-19 dashboard, accessed 5/2/2022.

The most recent count of new cases from W&M works out to just under 140 new COVID-19 cases per 100K population per day.   There has been no corresponding uptick in cases in the Virginia 18-24 population as a whole.

We’re now about two weeks away from graduation.  It will be interesting to see how the current outbreak evolves.  Even if this isn’t particularly dangerous for the young, you’re about to have the campus flooded with crowds of their parents, some of whom are likely to be in higher-risk categories.  In that context, this is an unfortunate turn of events.

Booster or not?

Separately, I’ve been strategizing over when to get my second booster.  I’m thinking, in light of this, maybe now wouldn’t be too bad a time.  It’s tough to say, particularly given that a lot of the W&M graduation events will be held outdoors, where risks of disease spread are inherently low.

The first issue with a booster shot is that you only get one.  As of today, there’s no approved third booster shot. Best not to waste it.

The second issue is that protection against any infection is short-lived (but protection against severe infection remains quite long-lived).  You get maybe a couple of months of enhanced antibody levels that will reduce your likelihood of any infection.  Then those return to baseline.  That’s why the CDC currently shows that those with booster shots are about half as likely to have some COVID-19 infection, but only about 5% as likely to die from COVID, compared to the unvaccinated.

Source:  CDC COVID data tracker, accessed 5/2/2022.

Given the low risk of transmission in the community, I’ve been saving mine.  I figure it would be smarter to get one this fall, in anticipation of a likely winter flu-and-COVID season.

Now I’m looking at two days of various graduation ceremonies at William and Mary, hanging out with a maskless crowd of students who are in the middle of a COVID-19 outbreak.

Hmm. Vax up now, or save it for the winter?  The booster is free, harmless, and helpful, of course I’m going to get it.  It’s just a matter of when.

Well, whatever I do, I’d better to it soon.  It takes a couple of weeks for antibody levels to rise after those vaccine shots.

Post #1493: W&M COVID uptick continues


Source:  Calculated from the W&M COVID-19 dashboard, and Commonwealth of Virginia counts of COVID-19 cases by age group.

This is just a quick post to note that William and Mary is still seeing about five newly-reported COVID-19 cases per day.   That rate has been roughly steady for the past couple of weeks.  On a per-capita basis, that’s well above the officially-reported rate for the 18-24 age group for Virginia as a whole.

I guess I’ll track this through graduation, as I will be in Williamsburg for that, and I’d like to have some estimate of the risks (or lack thereof) before attending any indoor ceremonies.

My guess is, I’ll be so thrilled to see my daughter graduate, I’m not going to pass on any events, COVID or not.  But I’m still going to calculate the odds of exposure.

Post #1472: William and Mary COVID-19 trend to 3/28/2022

Source:  Data from William and Mary COVID dashboard, Virginia data from Virginia Department of Health file of case counts by age group.

W&M just announced a mask-optional policy for the Williamsburg campus.  It may be worthwhile to continue to track the weekly update, even though nothing much is happening now.

As you can see above, there was a slight uptick in cases for both the William and Mary campus and for the 18-24 age group in Virginia as a whole.


Post #1467: W&M COVID-19 update to 3/21/2022


William and Mary didn’t post new numbers over spring break.  You also might want to take the most recent numbers with a grain of salt, again due to the  impact of spring break (and the potential for cases to have occurred over spring break, but not be reported to W*M).

Those caveats aside, taken at face value, the new-case rate on the William and Mary campus now appears to be on a par with the rate for 18-24 year olds, generally, in Virginia.  Really, the new case rate is so low (under one per day, as I calculate it, for this last reporting period) that, effectively, you’re looking at two numbers that are effectively zero, plus some random statistical noise.

Source:  Calculated from William and Mary COVID-19 dashboard.  I gap-filled the 3/14/2022 number by taking the average of the week before and the week after.  The 3/21/2022 rate assumes that if cases occurred over spring break, that would have been reported to W&M.  No idea whether that’s reasonable or not.

Post #1454: William and Mary COVID-19 trend to 3/7/2022


It’s not clear that this is still worth tracking.  The William and Mary student population is now down to an average of 2 per COVID-19 cases per day.  That down from about 15 per day, just two weeks back.  It’s still higher than the community rate in Virginia for 18-to-24-year olds.  But I don’t think it’s cause for concern for anyone. Continue reading Post #1454: William and Mary COVID-19 trend to 3/7/2022

Post #1446: COVID-19 trend at William and Mary, new case rate finally peaks.


Source:  Calculated from the William and Mary COVID-19 dashboard

The new COVID-19 case rate at William and Mary finally appears to have peaked.  This week saw less than half the number of newly-diagnosed cases compared to last week.   The rate is still about 4.5 times higher than the rate observed in the 18-24 population of Virginia.

Based on the most recent email from the W&M administration, they are no longer going to do contact tracing.  (That is, identifying the close contacts of known new COVID-19 cases, and checking those close contacts for infection.)  This means that the new case counts moving forward will not be strictly comparable to the data so far, because they will no longer contain (e.g.) asymptomatic individuals who were only found via contact tracing.

That said, at this point, I don’t think anyone cares.  Almost everyone on campus is immunized, case counts are falling, and as far as I know there have been no reports of severe illness from Omicron.  As of yesterday, W&M lifted their mask mandate for indoor spaces other than classrooms.

What will the new normal be?

All of that seems consistent with the slow return to normalcy.  Let’s all be glad that Omicron is substantially less virulent than Delta, and that vaccines (and particularly, the third or booster shot) remain reasonably effective at preventing severe illness.  All told, those changes bring COVID a lot closer to being “flu-like” in terms of health risks.

Elsewhere, I’ve made the case that in most parts of the country now, a boostered adult faces no more risk of hospitalization or death from Omicron than from flu, in a typical flu season.  As Omicron case counts continue to fall, I think that an increasing share of the population will come to more-or-less the same judgment.

My best guess for endemic COVID is that it will be accepted the same way that flu is, unless a more virulent strain arises.  Those who care will get a flu shot and a COVID shot every year.  Those who don’t, won’t.  Maybe wearing masks in flu season will become socially acceptable, as it is in much of Asia.  (I, for one, hope that’s true, now that we’ve woken up to the realities of aerosol spread of disease.)

As with flu, we’ll probably see a wintertime peak in COVID-19 activity in the Northern Hemisphere, because that’s the pattern for coronaviruses in general, and (so far) COVID-19 in particular.

Here’s flu, from the CDC:

Here’s a collection of coronaviruses other than COVID-19, from the source cited below:

Source: Potential impact of seasonal forcing on a SARS-CoV-2 pandemic DOI: Publication Date: 16.03.2020 Swiss Med Wkly. 2020;150:w20224 Neher Richard A., Dyrdak Robert, Druelle Valentin, Hodcroft Emma B. Albert J.

All of that would make sense, I think.

Blitz-demics.  The only thing that doesn’t quite make sense in this COVID-as-flu scenario is the effect of the extremely high contagiousness of COVID-19 relative to flu.  Typical seasonal flu has an R-nought of about 1.3 (per this scholarly reference).  Pandemic flu outbreaks such as the 1918 flu have an R-nought of perhaps 1.8 (same reference).  But Omicron (B.1.1.529) has an R-nought of about 15, and son-of-Omicron (BA.2) is about a 22.

In other words, where the average person with flu might go on to infect 1.3 to 1.8 others, absent any interventions, the average person with Omicron would infect 15 others, absent any interventions.

The upshot of that is that if immunity fades over time (and it does), when there is an outbreak of Omicron, it’s going to spread far faster than flu.  In round numbers, you’d have to guess about 10 times as fast, given that the R-nought is about 10 times as high.

This is a particular issue for “congregate living situations”, such as prisons, nursing homes, ships, barracks, and dorms.

You may or may not recall that early in the pandemic, COVID-19 swept through many U.S. prisons before anybody even thought to do anything about it.  It disabled the U.S.S. Theodore Roosevelt, again before anyone even considered any effective means to contain it.

I suspect that will become part of the new normal with endemic COVID-19.  As population immunity wanes, we’ll end up with “blitz-demics”, for want of a better term.  An outbreak of Omicron (or its successor) will run though a prison, campus, ship or workplace before anybody’s even really aware that there’s an issue.

But all of that — if it comes to pass — is a problem for the future.  Right now, things look better in the U.S. than in much of the rest of the world.  All we can do is hope that current U.S. trends continue.

Source:  Johns Hopkins data, via Google search.

Post #1440: William and Mary COVID-19 trend to 2/21/2022: Still moving in the wrong direction.


Source:  Calculated from William and Mary COVID-19 dashboard.  Virginia data were extrapolated from the most recent (2/18/2022) data by age, from the Virginia Department of Health.

For the past week, William and Mary saw an average of 15 newly-diagnosed COVID-19 cases per day.  That’s an increase compared to last week, and that now works out to be about seven times the rate of new cases in the 18-24 population of Virginia as a whole.

Plausibly this is not a serious threat to health, given the generally milder nature of Omicron, and given the generally high rates of vaccination and boosters among the student population. Plausibly.

That said, it’s hardly something to be proud of, and we appear to be under-performing relative to peer schools in Virginia.

Above are large (5000+ enrollment) Virginia colleges and universities with at least some on-campus residences, showing the rate of new COVID-19 cases per nominal total enrollment for the past week.  (These enrollments figures all exceed actual on-campus enrollment to a larger or smaller extent, including the number for William and Mary).

Even though this isn’t the cleanest of comparisons, it shows you that, on paper at least, of all the major residential colleges and universities in Virginia, William and Mary now ranks first in COVID-19 incidence. 

In fairness, there is a lot of variation in what’s being reported in the table above.  Not every comparison is a proper apples-to-apples comparison.  That said, for the ones that should be close to correct — e.g., U.Va — disease incidence at William and Mary looks to be out-of-line with our peers.

Probably not a huge cause for concern, all things considered.  But certainly nothing to be proud of, either.

Post #1434: William and Mary COVID trend to 2/14/2022


Source:  Calculated from William and Mary COVID-19 dashboard.  Virginia new case rate calculated from Virginia Department of Health data and Census population estimates by single year of age.

This week’s new-case number was an unpleasant surprise.  The rate of new cases among students at the Williamsburg campus is now more than three times the rate for 18-24 year olds in Virginia as a whole.

Even with the understanding that W&M students may be more likely to get tested, this seems like a significant difference.  As importantly, while new cases are trending down in Virginia as a whole, they appear to be trending up at William and Mary.

This is also completely at odds with a superficial reading of William and Mary’s 2/15/2022 email to parents (Subject:  [parents-l] W&M COVID-19 Updates), where they state that:

 "Currently, many of these metrics are trending favorably, ... we are encouraged that we are in a much better position than we were in early- to mid-January."

That’s a weirdly ambiguous piece of text.  You have to stop and realize that by “we”, they meant the U.S.A., and not William and Mary in particular.  Return to campus didn’t occur until the end of January, and William and Mary’s metrics are trending unfavorably.

To me, to the extent that anyone continues to worry about the health consequences of COVID-19, this current increase seems to be well worth tracking.  New case rates are falling throughout the country, but not at William and Mary.

So, what’s the issue with W&M students that is not present in that age group for Virginia as a whole?

If I return to that 2/15/2022 email, and as with that line above, try to read past the ambiguities and try to read between the lines, I have a pretty good guess as to what the main problem is.  Emphasis mine:

"One of the data points that does appear to be different this spring is the number of individuals being identified as close contacts. Given the high transmissibility of the Omicron variant, I encourage you to socialize in small groups with your core friends and colleagues and to meet outdoors whenever possible. For those that would like them, faculty and staff may order masks from the facilities management warehouse and students may pick up additional masks from the Sadler Center information desk. "

When I step back from all that polite talk, and focus on “socialize” and “masks”, my best guess is that the problem now is the exact same problem they’ve had in the past.  Probably, students have gone back to holding unmasked parties. 

That was the issue at the first return-to-campus outbreak under COVID.  That was the issue for the St. Patrick’s day outbreak last year.  It would be completely unsurprising if that were the issue now.

That’s purely guesswork on my part, but all the pieces seem to fit.

But why the seemingly nonchalant attitude on the part of the William and Mary administration?

Return briefly to last year’s St. Patrick’s day outbreak (Post #1099).  I think everybody took that one fairly seriously.  That outbreak generated 120 new cases in 11 days, or a rate of 11 new cases per day.  So, the current rate of daily new cases is now roughly what it was during the St. Patrick’s Day outbreak last year.

But while the case count is about the same as St. Patrick’s Day 2021, the health risks are vastly lower. That’s due to vaccination plus a milder strain of COVID-19.  CDC data show that full vaccination remains roughly 80% effective at avoiding hospitalization from Omicron, and that vaccination plus booster is is about 90% effective.  (You’d have to download the data from the references on the CDC vaccine effectiveness web page to find that.)  On top of that, the crude hospitalization rate for Omicron is about one-third that of prior variants.  All told, that’s something like a (1/(.2 x . 33)) = 15-fold reduction in health risk, per case, compared to the situation last year.  (No one has the data on significant health risks other than hospitalization, but I would expect all significant risks to be reduced roughly in proportion to the hospitalization risk.)  And so, the current 12 cases per day presents about the same population health risk as one new case per day would have, around this time last year.

With that in mind, it now makes more sense that William and Mary is dancing around the issue of parties and masks, now, when they took a lot firmer stand during prior periods that had roughly the same daily new case.

Again, guesswork on my part.  I can’t read their minds as to why the wording regarding socializing and masks is now so oblique.  But it makes logical sense.

All I can say for sure is that the metrics at William and Mary are not trending favorably.  COVID-19 may be approaching endemic status in a handful of areas, but the William and Mary campus is not yet one of them.  The seems well worth keeping an eye on for a while longer yet.

FWIW, I’m now of the opinion that for your average boostered individual, the health risk from COVID-19 now, in Virginia, is no higher than the risk from typical seasonal flu (explained here or here).  So I’m not trying to be alarmist at all.  I don’t see a huge risk here.  I’d just like to see the counts at W&M going down, as they are everywhere else.