Tag: nature

Fractional dosing of COVID vaccines may help more people get immunity faster

The advice to date has, quite rightly, to get any COVID vaccine that’s available to you. For me, that’s meant a double dose of AstraZeneca, and I’m happy about that.

But as the pandemic progresses, we need to be aware that some vaccines are more effective than others. This working paper, building on one published in Nature earlier this year, looks at how ‘fractional dosing’ of the Moderna and Pfizer vaccines could reach more people more quickly.

Needless to say, we shouldn’t be in the position where people in less developed countries are getting access to vaccines much more slowly than the rest of the world. But, pragmatically speaking, this may help.

We supplement the key figure from Khoury et al.’s paper to show that fractional doses of the Moderna and Pfizer vaccines have neutralizing antibody levels (as measured in the early phase I and phase II trials) that look to be on par with those of many approved vaccines. Indeed, a one-half or one-quarter dose of the Moderna or Pfizer vaccine is predicted to be more effective than the standard dose of some of the other vaccines like the AstraZeneca, J&J or Sinopharm vaccines, assuming the same relationship as in Khoury et al. holds. The point is not that these other vaccines aren’t good–they are great! The point is that by using fractional dosing we could rapidly and safely expand the number of effective doses of the Moderna and Pfizer vaccines.


One more point worth mentioning. Dose stretching policies everywhere are especially beneficial for less-developed countries, many of which are at the back of the vaccine queue. If dose-stretching cuts the time to be vaccinated in half, for example, then that may mean cutting the time to be vaccinated from two months to one month in a developed country but cutting it from two years to one year in a country that is currently at the back of the queue.

Source: A Half Dose of Moderna is More Effective Than a Full Dose of AstraZeneca | Marginal REVOLUTION

Who’s the pet? Tarantula or tiny frog?

I read recently that some tarantulas keep tiny frogs as ‘pets’. Of course, I had to do some more digging and found out that’s not quite true, and if it were, it would be more like the other way around (as some tarantulas are so docile!)

I’ve seen some “sources” (and I really do use the word source here in it’s least possible capacity) try to say that the frogs eat potential nuisances to the spider like ants, mites and other nasties which is why the spider keeps it around. This is silly for a few reasons. 1. Tarantulas line the entire length of their burrow (which can be several feet deep) with thick sticky web. This prevents things like small insects from burrowing into or walking into their homes. Anything large enough to do so is too big to be eaten by the frog. 2. These frogs don’t even eat stuff like mites or springtails. The prey items are far too small for them to bother with. 3. If there are enough ants to bother a tarantula of this size the frog is going to die if it sticks around anyway.

Source: Is it true that some tarantulas keep tiny frogs as pets? – Quora

In a dark place

Last year, I remember being amazed by how black a new substance was that’s been created by scientists. Called Vantablack, it’s like a black hole for light:

Vantablack is genuinely amazing: It’s so good at absorbing light that if you move a laser onto it, the red dot disappears.

However, it turns out that Mother Nature already had that trick up her sleeve. Birds of Paradise have a similar ability:

A typical bird feather has a central shaft called a rachis. Thin branches, or barbs, sprout from the rachis, and even thinner branches—barbules—sprout from the barbs. The whole arrangement is flat, with the rachis, barbs, and barbules all lying on the same plane. The super-black feathers of birds of paradise, meanwhile, look very different. Their barbules, instead of lying flat, curve upward. And instead of being smooth cylinders, they are studded in minuscule spikes. “It’s hard to describe,” says McCoy. “It’s like a little bottle brush or a piece of coral.”

These unique structures excel at capturing light. When light hits a normal feather, it finds a series of horizontal surfaces, and can easily bounce off. But when light hits a super-black feather, it finds a tangled mess of mostly vertical surfaces. Instead of being reflected away, it bounces repeatedly between the barbules and their spikes. With each bounce, a little more of it gets absorbed. Light loses itself within the feathers.


Source: The Atlantic