How Not to Infect Others With Your Covid-19

Infectiousness Lasts and Lasts

With so many people getting covid-19, there is a lot of confusion about how long to isolate, and when it’s safe for others for you to get out into the world.

The public health guidance from the CDC—end isolation after five days—is sending people back while many of them are still contagious. And we know from many previous studies that mask-wearing accounts for only a small risk reduction (for example, about 25% in one multisite study). (Mar. 10th post)

There is a relative flood of recent articles and a few new studies discussing this. Some examples:

An Alaskan study found about 80% of symptomatic patients antigen-positive after five days! (CDC.gov - 2/25/22)

An earlier study from UK said much the same thing, and we talked about that in our Feb. 2nd post.

A good story summarizing the ongoing discussion recently appeared in The Conversation - 5/29/22.

Why This Still Matters

Remember, the days of covid-19 are far from over—U.S. deaths were up by a third over the last week (Washington Post):

And, as we have mentioned, protection from vaccinations and boosters is waning: "The vaccinated made up 42 percent of fatalities in January and February during the highly contagious omicron variant’s surge, compared with 23 percent of the dead in September, the peak of the delta wave ...”

Washingtonpost.com 4/29/22

So, to reduce the spread of the disease, the best practice is to ignore any specific number of days, and wait until you have two negative antigen tests 24 hours apart. Or, if you want to be especially careful, three negative tests. Stay safe out there! (Apr. 7th post)


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Top Ten Covid Myths - Busted

One of the reasons, perhaps, that a lot of folks are not following the current best practices for covid risk reduction is that they have not updated their basic beliefs. A lot of things have changed. Either the earlier information turned out to be wrong, or the virus itself has changed.

So here is my list of the top ten covid myths - debunked (not in any order of importance), along with links to the past blog posts or other references.

1. I already had covid, so now I’m immune. ==> Probably wrong. “Natural immunity” doesn’t last forever. I’ve seen verified reports of as little as 23 days time until a second, separate infection. With Omicron. Or for some people, it could be as long as six months or more. I’m going to assume three months because that’s what the NFL assumed with Omicron. See Jan. 27th post.

2. I’ve been vaccinated/boosted, so now I’m immune. ==> Probably wrong. The vaccinations that we got in early 2021 are now over a year old. One can deduce that the CDC thinks there’s not much protection left from these shots, since you are eligible for a booster after five months. And another booster after only four months. See Apr. 19th post.

3. To make my event safer, I need to require all attendees to have proof of vaccination or boosting. ==> This makes no sense to me. Except for the small number of people who will have had shots within the last four or five months, it won’t appreciably reduce the risk to the group.

4. Eating inside in restaurants must be OK since they are letting us do it. ==> It’s a value judgment whether it’s OK, that is, worth the risk. It’s a fact that in a large study in 11 cities, the number of covid-19 cases was more than double in the cities allowing inside dining. See Dec. 15th post.

5. It’s got to be one or the other: masks are really good at reducing risk, and worth the bother - OR - masks aren’t much good at all and not worth the bother. ==> Both true! If you wear a tight-fitting, N95 mask, it’s going to reduce your risk a lot—I figure it as a factor of ten. If you wear a surgical mask (always gaping holes at the side) or a cloth face covering that doesn’t fit very well, it’s not going to do much good. For example, a large study of the covid-19 infections compared schools with and without mask mandates, and found that masks reduced the case rate by about 25%. See Mar. 10th post.

6. It doesn’t matter about being inside or outside—I can just stay six feet away from everyone and I’ll be OK. ==> Wrong on both counts. Being outside is the safest possible environment—there are hardly any documented cases of transmission via the outside air, and a computer simulation just made the same point (see May 20th post). And the myth about six feet was busted over a year ago, yet you still see lots of places with plexiglass barriers whenever people have to be closer together than the magical six feet. Maybe that’s fine as a feel-good measure, but it does make it hard to hear. See Nov. 24th post.

7. I feel the air blowing on me from some kind of air conditioning or fan system, so that must be doing something to make the air safe and free of viruses. ==> USUALLY WRONG! Most of the air being blown around is just recirculated air from within the room or from nearby rooms also, all mixed together. For the air conditioning units you see hanging on the walls, that’s ALL it is—no fresh outside air (virus-free) at all! This air will include all the exhaled virus from infected people currently in the room, PLUS the lingering virus from those who have been in the room recently. See Feb. 16th post.

8. There’s no way to tell in real time whether the air is full of covid-19 virus. ==> Technically true, but there is an excellent substitute, readily available. And that is to use an accurate carbon dioxide meter, from which you can determine the amount of true fresh air per person in the room. The more incoming fresh air (and corresponding exhaust air), the less virus, and vice versa. With the Safetulator™ Fresh Air Meters available on this website, you get a simple green-yellow-red assessment of the air in real time. See Apr. 29th post.

9. If I think I might have covid-19, I’ll just take a home antigen test, and if the result is negative, then I’m in the clear. ==> Wrong. Or often wrong, to be exact. With Omicron, a negative result from an antigen test is wrong about a third of the time! A positive result can be trusted, but a negative one is about like not having taken a test at all. Do you want to go out into the world with a one-third chance of spreading the virus to the people around you? But good news—you can make the test accurate by retaking it 24 hours later (and even better, a third time after another 24 hours). With multiple negative tests, it’s a good chance this is the correct result. See Feb. 2nd post.

10. It’s no big deal if I get Omicron because it has turned out to be a mild disease anyway. ==> Probably wrong. Yes, early reports speculated/hoped that this was the case. Further studies found that Omicron can be more deadly. The latest study with this conclusion was from Massachusetts, so was this a regional result, or perhaps just the first example of a more rigorous investigation? And even a mild case can lead to “long-covid” (more on this in a future blog post). NBC.com 5/20/2022


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Levity and Gravity

A Little Levity

Ending the Pandemic. We desperately want covid to be behind us. Some of us are declaring that this is the case, facts be damned. Not an unusual attitude in the modern world. Here’s a college that has found that to end the covid-19 pandemic, all you have to do is stop reporting cases, eliminate all special risk-reduction practices, and put an end to the emergency paid leave policy.
Springfield News-Leader.com 5/18/2022

Predicting the Future. Oregon seems to have some super computers that can predict the future with precision: “The state is expected to peak at 321 covid-19 hospitalizations on June 10.” Share with the rest of us?
KEZI.com 5/18/2022

Trumpeting the Obvious. A big research computer study says being outside is safer than being inside, and that holding a gathering with everyone doing a PCR test ahead of time is better than requiring vaccinations. Seems I’ve heard that somewhere before.
KXAN.com 5/10/2022

And Now For Something Completely Different

The 100,000 new cases a day being reported and tracked are likely low by a factor of four or five, per multiple estimates. Dr. Eric Topol says: "The real number of cases is likely at least 500,000 per day, far greater than any of the US prior waves except Omicron.”

“We have a highly unfavorable picture of: (1) accelerated evolution of the virus; (2) increased immune escape of new variants; (2) progressively higher transmissibility and infectiousness; (4) substantially less protection from transmission by vaccines and boosters; (5) some reduction on vaccine/booster protection against hospitalization and death; (6) high vulnerability from infection-acquired immunity only; and (7) likelihood of more noxious new variants in the months ahead.”

And he reports that vaccinated individuals account for 42 percent of the deaths during the Omicron wave, which is an all-time high percentage.
Ground Truths 5/15/2022


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Hosting a Minimal-Risk Gathering

Large gatherings, and the resulting covid-19 cases coming from them, have been in the news lately. It’s interesting that a lot of the national news has the viewpoint that it’s not really news at all, it’s just par for the course, nothing more you can do about it, everyone knew the risk, the event was worth it, if you want to do better, go get another shot, and the like.

This "nothing more you can do about it” approach is dead wrong. All the recent events I have read about have missed the boat on more than one of the following effective safety measures:
- PCR pre-tests,
- careful symptoms screening,
- great fresh air ventilation, and
- contact tracing.

For example, the Washington correspondents’ dinner required negative tests, but used same-day antigen tests, which are infamous for a high level of false negative results (see Apr. 7th post - and this was known as far back as the Jan. 7th post).

Even though the spring surge continues - U.S. cases up 25% in the last week - few people choose to wear masks any more. Therefore, let’s see how good a job we can do without requiring masks. Here is what I would do if I were hosting a one- or two-day gathering and wanted to employ all reasonable and effective measures to reduce the covid-19 risk (with references to previous posts).

Before the gathering:
- let everyone know what will be the “rules of the road” including a clear list of symptoms
- anyone with a hint of any of the symptoms, please stay home (Jan. 20th post)
- require a negative PCR test, preferably within 24 hours of arrival—48 hours at the most (Apr. 7th post and Jan. 20th post)
- I would not require vaccination, boosting, or recent “natural immunity” (Mar. 29th post and Jan. 27th post).

Upon arrival at the gathering:
- ask each person to make sure they don’t have any of the symptoms on the list
- collect the proof of negative PCR test results, or ask participants for verbal confirmation
- confirm contact information to allow good contact tracing.

Holding the gathering:
- arrange to hold the event, or most of it, outside
- if not possible for the whole event, have excellent fresh air ventilation for the inside portions
- excellent ventilation to me is twice the CDC/WHO levels, that is, CO2 less than 600 ppm (or higher if supplemented by in-room air purification)
- present the CO2 readings prominently with large meters such as those available via this web site (Apr. 29th post)
- do no dining inside—a serving line can be inside, but the seating will be outside (Dec. 15th post)
- do no singing inside (about double the risk, upcoming blog post).

After the gathering:
- ask participants to get a PCR test right away at the first hint of any symptoms
- ask participants to promptly report any positive test results
- set up a group email or equivalent so participants can self-report their positive test results without violating HIPAA
- participants may want to check to see if they have an asymptomatic case by doing a PCR test (or two, Mar. 29th post) three days after the event
- participants may want to isolate until they get their negative test results.

If these steps are followed, organizers will know that they have literally done everything practical and effective to minimize the risk. Of course, individuals may choose to mask up for a bit of additional safety for themselves and those around them.

To get one of the meters mentioned above, properly calibrated per CDC and WHO recommendations, email (safetulator@kohlerandlewis.com) or call Suzanne (603-352-4828)—the price is $229, including shipping.


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Managing the Spring Surge

1. The spring surge continues. Cases are rising fastest, of course, with hospitalizations lagging, and deaths lagging further.

And Vermont has the highest per capita case rate of any state (behind only Puerto Rico).

2. Outbreaks are happening with group gatherings.

Mlive.com 4/26/2022
NBC29.com 4/26/2022

3. “The Big Meter” can help you avoid hosting an outbreak.

Increasing the fresh air in a building, particularly in this mild spring weather, is one of the easiest ways to reduce the covid-19 risk. The word is starting to get out.

Fresh air (or lack of it) was on display this week at the Better Buildings by Design conference and show in Burlington, Vermont, using our Safetulator Fresh Air Meter.

On Wednesday at 6:45 am, the level was looking good, “in the green”, when few people were in the room.

But by 8:20 am, the reading was in the "red zone," indicating lack of fresh air to dilute any covid-19 virus that was present. This gave a good demonstration, showing what happens with a fixed amount of fresh air ventilation that does not increase when more people are in the room.

To get one of these meters, properly calibrated per CDC and WHO recommendations, email (safetulator@kohlerandlewis.com) or call Suzanne (603-352-4828)—the price is $229, including shipping.



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The Spring Surge Is Here

It looks like we are at the start of a spring surge. Nationally, cases are up 19% over last week (and Vermont has the second highest cases rate per capita of any state). More in some places, such as Manhatten.

Amny.com 4/17/2022

And the models are predicting further increases. "Daily COVID-19 cases are projected to increase 93.6 percent nationwide in the next two weeks, according to modeling from Mayo Clinic. "

Beckershospitalreview.com 4/18/2022

I hope it will be like last April’s (see graph below)—rise a bit, then taper off for the summer as we spend more time outside, and as schools close for the spring. But with most mitigation measures cancelled, it feels to me personally to be a riskier time than that of last spring, when we still had mask mandates.

Covidactnow.org 4/18/2022

Just at the wrong time, old vaccinations and boosting are pretty much worn out. So-called breakthrough cases are now common, especially when people congregate indoors without masks, and without verifying good fresh air ventilation. The one good thing, if you can call it that, is that there is no longer any medical need to require proof of vaccination or boosting, and many organizations are dropping these rules.

Reviewjournal.com 4/15/2022
Jsonline.com 4/15/2022
Forbes.com 4/7/2022
Thehill.com 4/8/2022



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