Covid things

2021-07-27

How long does covid-19 immunity last?

According to a British Medical Journal peer-reviewed article, it may be as long as a few years. Antibodies don't last as long as hoped, but the T and B cells may carry memory for years. While some cases of severe infection may produce strong and lasting immune response, vaccination is more reliable (and safer). Booster doses may be required.

Especially if vaccination is slow and leaves large numbers of unvaccinated people who can become carriers.

2021-04-25

What works and what does not

The latest from AIIMS, about what works, and, importantly, what doesn't.

• Remdesivir, steroids, plasma, Tocilizumab, and Favipiravir are some of the most widely used treatments for COVID-19.

• According to AIIMS’ director Randeep Guleria, the timing of using these drugs — depending on the condition of a COVID-19 patient — is critical in their effectiveness.

• Using them too early or too late could result in harmful side-effects.

The article from Business Insider India has clears up some facts in a simple and direct style.

Please don't stock up and self-medicate. You would not only be risking your health, but also depriving those who really need it from the medicine.

However, an April 2020 paper suggests that, to completely deactivate the virus in a sample with a high viral load/dirty sample requires 92C for 15 minutes. Unfortunately, this also fragments the RNA, rendering it undetectable. So, lab technicians need to be very careful and researchers recommend that they should "combine the more extended lower-heat protocol with chemical sterilization to improve laboratory safety while preserving the optimal efficiency of virus detection."

For the rest of us: boil doubtful stuff for 15 minutes, or use a chemical like 70% ethanol or detergent/soap solution for 20 seconds minimum (sing happy birthday twice, slowly). For stuff that gets destroyed by any of these methods, UV irradiation can be used as an alternative where appropriate.

Reference: Article by Dr. Liji Thomas, MD, in www.news-medical.net.

2021-04-16

New CDC (USA) guidelines on COVID19 and disinfection

Highlights:

1. Contaminated surfaces are way down on the list of potential infections. Don't waste time wiping down everything and using gloves (unless of course you work in a COVID19 hospital). "In most situations, cleaning surfaces using soap or detergent, and not disinfecting, is enough to reduce risk." It's more important not to bring those contaminated hands to nose, mouth and eyes (Wear masks! Don't touch eyes)

2. Transmission is via fomites (droplets containing virus).

Note: fomites are now known to be smaller and travel further than earlier suspected. Old research could not detect fomites; newer technology shows transmission up to 3 metres away from a person with high viral load. It also depends on the air currents. (Wear masks!)

3. Three days after an infected person leaves a room, it's safe. One day later, it can be safe if it is ventilated. The shortest periods are a few hours. (Wear masks!)

4. Disinfection by fogging and misting is of dubious benefit and dangerous if not done properly. Don't spray people. (Wear masks!)

5. "The risk of fomite transmission can be reduced by wearing masks consistently and correctly, practicing hand hygiene, cleaning, and taking other measures to maintain healthy facilities." (Wear masks!)

Link to the CDC article.

2021-04-09

Beware the vaccination with live virus!

People act as if merely signing up for the shot means they are 100% immune from all infections. The reality is that your immune system needs at least three months to gear up, so a shot today means mid-July before you have reasonable chances of minimising the effects of any COVID19 you catch (because vaccination does not mean you are immune, it merely means your body can fight it off better).

Trust me. I know. I am around to tell you this because I survived three* deadly infections because of vaccination. Note that I still got them. But I'm around.

Give your body a chance. Follow MSSD: mask, sanitise, social distance.

Otherwise, you are going to end up vaccinating with live virus. And worldwide clinical trials show that you have a worse than 1.5% chance of dropping dead from using live virus, especially if you're older or have some other sickness.

2021-01-03

Are vaccinations a guarantee of freedom from infection?

No.

I got all the DPT and booster shots and still got diphtheria. (Try not to get it; it's horrible).

But, probably because of whatever partial immunity the vaccinations bestowed, I didn't die of it (oh, you guessed that, did you?, whatte genius by jove).

Will I take a vaccine shot if/when offered? You blotty well bet I will.

(I even got vaccinated in my 40s for something that the doc categorically told me is unproven for people older than 25. To my mind, any benefit is better than zero.)

2020-12-25

Understanding the negative result of the COVID test

At random, if you select anyone in India, they have a 1:134 chance of having Covid19.*

Now, if you give them an RTPCR test (with sensitivity of 77.7% and specificity of 98.8%), and they get a positive result, that means that their odds of having it are, wait for it, 1:2.

It's not dead sure they have it. If they get a negative result, that means the odds are 603:1 of not having the disease. Not dead sure either!

Of course, that also assumes that they are picked totally randomly. However, that is never true, is it? If they've been roaming maskless in large groups and someone known to them, whom they have met in the last 2 weeks has come down with it, their odds will be very different. And those are typically the people who are dragged, kicking and screaming, to the testing centres.

Those people's odds would start at no less than 1:67. So the positive test would make the odds 1:1 (which is why they go to quarantine), and the negative test would mean that the odds are only 15:1 that they are actually free of the disease (which is why they go to self-isolation if they have been exposed, test or no test).

So, even if they wave their negative test at you, don't believe them. They are 9 times more likely to be infectious than a random person.

No mask, no belief. ✊😁

[The Bayes factor is 64.75. That's what we are multiplying with to estimate the revised odds for the false positive. For the false negative, it is 4.4].

For more on the maths, check out this excellent video from 3 blue 1 brown. It's 21 well-spent minutes.