Science desk
< December 20	<< Nov \| December \| Jan >>	Current desk >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

December 21[edit]

Battle of the units[edit]

The FDA's emergency use authorization of Moderna's vaccine indicates the booster dose as 0.25 mL.^[1] Moderna says a 50-microgram booster dose generates 37 times a low amount of neutralizing antibodies against the Omicron variant.^[2] I have nu clue how to assess the effectiveness of 37 × low, but what I'd like to know now is how to relate the FDA's 0.25 mL to Moderna's 50 micrograms. --Lambiam 09:12, 21 December 2021 (UTC)[reply]

From the Reuters article, it seems Moderna did some testing with 50/100 μg (0.05/0.1mL) of booster. The FDA approved 0.25mL. That is not in itself a contradiction, unless you want some details about the approval process for the boosters.

I would also say that the Moderna PR is quite crappy science. (Presumably there is good science being done backstage, but it is not complete yet.) As we (I?) have said multiple times, antibody titration is easy to measure but it does not tell you much about whether subjects will resist better to infection/symptoms/grave symptoms/death. "37 times!" sounds impressive but it tells you zilch. Presumably, the comparison is something like ~1 week with or without booster ~6 months after initial schedule, so of course antibody levels have decreased in those 6 months and exposure to the antigen kicks them back up. But does it actually improve immunity one month after booster? Tigraan^{Click here for my talk page ("private" contact)} 11:03, 21 December 2021 (UTC)[reply]

Page 28 of the FDA link Lambian supplied has the answer, I think. Each 0.5 mL dose of Moderna COVID-19 Vaccine contains 100 µg of nucleoside-modified messenger RNA (mRNA) encoding the pre-fusion stabilized Spike glycoprotein (S) of SARS CoV-2 virus. Each 0.5 mL dose of the Moderna COVID-19 Vaccine contains the following ingredients: a total lipid content of 1.93 mg (SM-102, polyethylene glycol [PEG] 2000 dimyristoyl glycerol [DMG], cholesterol, and 1,2-distearoyl-sn-glycero-3-phosphocholine [DSPC]), 0.31 mg tromethamine, 1.18 mg tromethamine hydrochloride, 0.043 mg acetic acid, 0.20 mg sodium acetate trihydrate, and 43.5 mg sucrose. Each 0.25 mL dose of Moderna COVID-19 Vaccine contains half of these ingredients. So most of what actually goes into a person's arm (the 0.5 mL in the case of a full dose) is sugar water, with just 100 µg (= 0.1 mg) of the synthetic mRNA active ingredient wrapped in a lipid nanoparticle (see the SM-102 article). The amazing bit of science is how such a tiny amount of mRNA can provide immunity to the disease. Mike Turnbull (talk) 14:24, 21 December 2021 (UTC)[reply]

So the 0.25 mL dose contains 50 micrograms of mRNA; the two sources are talking about the same dosage. Thanks, issue solved. I'll leave the tougher question of determining the height of 37 × low to better times. --Lambiam 21:58, 21 December 2021 (UTC)[reply]

Try botulinum toxin on for size. ~100 nanograms is enough to kill an adult human. Yet with appropriate care and dosage we can still inject it safely into people. More extremely potent stuff listed at LD50. --47.155.96.47 (talk) 02:56, 23 December 2021 (UTC)[reply]

Resolved

Looking for info.[edit]

Are there medical trials about taking adult stem cells, make them epigenetically younger, and putting them back in?--2A02:908:426:D280:7100:3AFC:91AC:329B (talk) 14:36, 21 December 2021 (UTC)[reply]

If there were or are, they would likely be reported in the journal Rejuvenation Research, which you might be able to consult through a good library. See also our article on the related topic of Stem-cell therapy. {The poster formerly known as 87.81.230.195} 90.193.131.122 (talk) 19:40, 23 December 2021 (UTC)[reply]

Ominous dominance[edit]

I see news items from all over the globe reporting that omicron is to become, or has become, the (locally) dominant variant. Usually, the tone is ominous, as if omicron's gaining dominance is when its threat becomes really serious. It is not just journos saying such things, but also epidemiologists and hospital officials being interviewed. Is there any basis for assigning particular importance to the event? Consider a scenario in which the reigning variant is rho, but chi is on the rise. In two countries, Abracadabria and Balonia, the respective curves are the same up to the 31st of January. But then they suddenly start to show a difference; chi gains dominance in Abracadabria on 7 February, and in Balonia only on 28 February. So, in this scenario, was Abracadabria hit more heavily? (Some additional info. The cause of the divergence was that the prevalence of rho quickly diminished in Abracadabria after 31 January, while it remained unabated in Balonia. The rise of chi proceeded the same in both countries.) --Lambiam 22:26, 21 December 2021 (UTC)[reply]

How often are there 3 non-rounding error variants in a country at the same time? Sagittarian Milky Way (talk) 23:38, 21 December 2021 (UTC)[reply]

Is there a relation between this question and mine, beyond both mentioning "variant" and "country"? --Lambiam 11:26, 22 December 2021 (UTC)[reply]

The sum of all variants is 100%. If only 1 or 2 are really circulating at a time your scenario cannot happen. Sagittarian Milky Way (talk) 14:33, 22 December 2021 (UTC)[reply]

I think you are mistaken. The sum of their prevalences can be much less than 100%. Using the letter P to denote prevalence, we can have the following:

Date	Abracadabria	Balonia
31 January	P_rho = 8% P_chi = 2%	P_rho = 8% P_chi = 2%
7 February	P_rho = 4% P_chi = 5%	P_rho = 8% P_chi = 5%
28 February	P_rho = 2% P_chi = 9%	P_rho = 8% P_chi = 9%

--Lambiam 15:43, 22 December 2021 (UTC)[reply]

When they said 73% of America is Omicron and the rest is mostly Delta they didn't mean everyone is infected. I assume this form of percentage is in the news more than prevalence cause it sounds more dramatic than "a few percent of everyone has omicron right now", especially to anti-mask idjuts who are bad at exponential-ish sigma-shaped curves. Sagittarian Milky Way (talk) 16:29, 22 December 2021 (UTC)[reply]

Prevalence would also be harder to estimate accurately, percent of reported positive tests that have omicron vs percent of positives that don't is what it is. Sagittarian Milky Way (talk) 21:51, 22 December 2021 (UTC)[reply]