Malo optimizma

ponedjeljak , 27.12.2021.


Jedan optimistični članak, barem za mene, prenosim ovdje u cijelosti:



Omicron may not be the final variant, but it may be the final variant of concern




Ben Krishna, University of Cambridge

It is controversial whether viruses are alive, but – like all living things – they do evolve. This fact has become abundantly clear during the pandemic, as new variants of concern have emerged every few months.



Some of these variants have been better at spreading from person to person, eventually becoming dominant as they out-compete slower versions of SARS-CoV-2, the virus that causes COVID-19. This improved spreading ability has been ascribed to mutations in the spike protein – the mushroom-shaped projections on the surface of the virus – that allow it to bind more strongly to ACE2 receptors. ACE2 are receptors on the surface of our cells, such as those that line our airways, that the virus attaches to in order to gain entry and start replicating.



These mutations allowed the alpha variant, and then the delta variant, to become globally dominant. And scientists expect the same thing to happen with omicron.



The virus cannot, however, improve indefinitely. The laws of biochemistry mean that the virus will eventually evolve a spike protein that binds to ACE2 as strongly as possible. By that point, the ability of SARS-CoV-2 to spread between people will not be limited by how well the virus can stick to the outside of cells. Other factors will limit virus spread, such as how fast the genome can replicate, how quickly the virus can enter the cell via the protein TMPRSS2, and how much virus an infected human can shed. In principle, all of these should eventually evolve to peak performance.



Has omicron reached this peak? There is no good reason to assume that it has. So-called “gain-of-function” studies, which look at what mutations SARS-CoV-2 needs to spread more efficiently, have identified plenty of mutations that improve the spike protein’s ability to bind to human cells that omicron doesn’t have. Besides this, improvements could be made to other aspects of the virus life cycle, such as genome replication, as I mentioned above.



But let’s assume for a second that omicron is the variant with maximised spreading ability. Perhaps omicron won’t get any better because it is limited by genetic probability. In the same way that zebras haven’t evolved eyes at the back of their heads to avoid predators, it’s plausible that SARS-CoV-2 can’t pick up the mutations required to reach a theoretical maximum as those mutations need to occur all at once, and that is just too unlikely to emerge. Even in a scenario where omicron is the best variant at spreading between humans, new variants will emerge to handle the human immune system.



After infection with any virus, the immune system adapts by making antibodies that stick to the virus to neutralise it, and killer T-cells that destroy infected cells. Antibodies are pieces of protein that stick to the specific molecular shape of the virus, and killer T-cells recognise infected cells via molecular shape as well. SARS-CoV-2 can therefore evade the immune system by mutating sufficiently that its molecular shape changes beyond the immune system’s recognition.








This is why omicron is so apparently successful at infecting people with previous immunity, either from vaccines or infections with other variants – the mutations that allow the spike to bind to ACE2 more strongly also reduce the ability of antibodies to bind to the virus and neutralise it. Pfizer’s data suggests that T-cells should respond similarly to omicron as to previous variants, which aligns with the observation that omicron has a lower fatality rate in South Africa, where most people have immunity.



Importantly for humanity, past exposure still seems to protect against severe disease and death, leaving us with a “compromise” where the virus can replicate and reinfect, but we do not get as severely sick as the first time.



Probable future



Herein lies the most probable future for this virus. Even if it behaves like a professional gamer and eventually maxes out all its stats, there is no reason to think that it won’t be controlled and cleared by the immune system. The mutations that improve its spreading ability do not greatly increase deaths. This maxed-out virus would then simply mutate randomly, changing enough over time to become unrecognisable to the immune system’s adapted defences, allowing waves of reinfection.



We might have COVID season each winter in the same way we have flu season now. Influenza viruses can also have a similar pattern of mutation over time, known as “antigenic drift”, leading to reinfections. Each year’s new flu viruses are not necessarily better than last year’s, just sufficiently different. Perhaps the best evidence for this eventuality for SARS-CoV-2 is that 229E, a coronavirus that causes the common cold, does this already.



Omicron will therefore not be the final variant, but it may be the final variant of concern. If we are lucky, and the course of this pandemic is hard to predict, SARS-CoV-2 will probably become an endemic virus that slowly mutates over time.



The disease might very likely be mild as some past exposure creates immunity that reduces the likelihood of hospitalisation and death. Most people will get infected the first time as a child, which could occur before or after a vaccine, and subsequent reinfections will barely be noticed. Only a small group of scientists will track SARS-CoV-2’s genetic changes over time, and the variants of concern will become a thing of the past – at least until the next virus jumps the species barrier.The Conversation



Ben Krishna, Postdoctoral Researcher, Immunology and Virology, University of Cambridge



This article is republished from The Conversation under a Creative Commons license. Read the original article.


Keksići

petak , 24.12.2021.


Najjednostavniji, koje možemo raditi skupa...
A radimo ih godinama već.
Netko vadi sastojke,
Netko vadi vagu,
Netko ih mijesi rukama,
Netko smjesu valja po stolu,
Smiju se,
Smijemo se.
Razgovaraju o omiljenim Božićnim pjesmama,
pa ih pjevaju.
govore kolačima bez kojih nikada više neće moći živjeti.
Bez kojih Božić nije Božić.
Pokušala sam prije dati neki drugi prijedlog, neki drugi recept: ne.
Vodili smo prave male ozbiljne razgovore o tome
o keksićima koji ne smiju promijeniti ni sadržaj ni formu
jer predstavljaju to nešto
naše
malo
slatko
Božićno čudo.
...
Sretan Božić svima.

Buongiorno bambini!

utorak , 21.12.2021.





Irska :)


Kolarin

subota , 18.12.2021.



Što me gledaš, mili?
Lezi tamo i ne cvili!
Znam koja je ura!
Ledeno je, dere bura!
Ne vodi me do vrata!
Nervoza me hvata!
I ne skači na kvaku!
Znam te u dlaku!
I mošu ti svaku!
Izdrži malo!
zar ti nije stalo
da bura malo
mola!?
ok.
idemo.
ne skači!
bunda se oblači.
ne tlači!
otvaraju se vrata.

Kolarin oko vrata!
Povodac od hvata!
Šetnja od pola sata!
Sloboda je
...
fiziološka potreba.


Moronic

utorak , 14.12.2021.

Nekoliko linkova:


"Epidemiolozi, HZJZ, EMA i ECDC, poručuju da booster dozu cjepiva možete primiti već nakon 3 mjeseca od zadnjeg cijepljenja. S povećanom otpornosti na COVID-19 bit će sigurnije uploviti u Novu godinu. Mislite na svoje i tuđe zdravlje!" V. Beroš, Tweeter, 10.12.2021

Na pitanje hoće li se cijepiti booster dozom iako je prebolio covid-19 te je cijepljen dva puta, Beroš je kazao da se nedavno testirao i da ima iznimno visok broj antitijela te da mu treća doza nije preporučena.
"Međutim, kada to struka procijeni - nemam nikakvih problema ponovno se testirati i cijepiti", dodao je ministar.
, V. Beroš za Jutarnji list, 11. 12. 20021.

Uistinu, ministre, s obzirom da ste jučer rekli da imate „iznimno visok broj antitijela“ bilo bi korisno da preciznije kažete što znači „iznimno visok“, a uzgred i je li taj kriterij isti kada se radi o uvaženom ministru i lokalnom poštaru. M. Selak-Raspudić za 24sata, 12.12.2021

Ja svojim pacijentima savjetujem da se svakako cijepe booster dozom. Po meni i po službenom stavu HZJZ-a ne propisuje se serološko testiranje na antitijela prije docjepljivanja booster dozom. Stvar je u tome što nitko nikad nije napisao koliko je antitijela gornja, a koliko donja granica da bi se znalo po tome koliko je antitijela potrebno imati, pa da se ne treba uzeti booster doza. Brojne su metode i granične vrijednost dr. M. Venus za Index, 13.12.2021


Ide li mi linkanje ili još moram vježbati?

Btw, što vi mislite o svemu i mislite li uopće o ičemu više?

Googlate li?

srijeda , 08.12.2021.



Pokus

petak , 03.12.2021.


Dolazi mi dijete danas sa radnom knjigom iz kemije da joj pomognem oko pokusa kojeg treba napraviti, doma naravno.
Kristalizacija, vidim.
Kristalizacija soli.
Nema problema, improvizirat ćemo, nas dvije alkemičarke.
Nakon što sa štednjaka sklonimo lonac s današnjom vrlo uspjelom juhom, kuhinju pretvaramo u prvoklasni laboratorij.
Laboratorij kojeg bi se zasigurno postidio svaki eminentni i vrlo citirani znanstvenik svjetskog renomea. Ali nama to ne smeta, pokus je jednostavan, i mi uopće ne izmišljamo ništa novo. Dostajat će i naša mala kuhinja za to.
Kratko pogledom skeniram upute, tek toliko da ih usporedim sa vlastitim sjećanjem. Sve znam. Galica, s kojom sam ja radila davno, i sol, koju ćemo mi koristiti, ne iziskuju razliku u postupku.
Dijete pribavlja materijale: opranu staklenku, konac, otpisanu olovku.
Mjerimo vodu, sol na žlice.
Stavi još, kažem.
Zašto?, pita.
Stavi, čini mi se, koliko se sjećam, da voda mora biti jako zasićena.
Stavljamo otopinu kuhati i sol nestaje.
Još soli, i još malo, i još koje zrno za svaki slučaj.
Za svaki slučaj - jer eksperiment ne mora nužno i uspjeti.
Mi ne znamo točno, zato i eksperimentiramo valjda, mislim u sebi.
Miješa, promatra što se događa i govori: Mogle smo tako iskuhavati i more. Smijem se; Mogle smo, ali tko bi ugrabio loncem toliko mora.
Slanu otopinu smo ulile u staklenku, na olovku smo privezale konac u obliku omče i uronile ga u nadi da će se kristali uloviti baš kako bi trebali.
Sada samo trebamo čekati.
Sedam dana?
Što je to za ogrlicu od soli...