A qué te refieres con que solo se sumará CureVac? No habrá J&J o Noavax aquí?goupri escribió:De aquí a verano a priori y en caso de que salga bien solo se sumará CureVac (mRNA).Green Eyes escribió:Je, pues en esta carrera por tener vacunas y vacunar a cuanta más gente mejor y tener más dosis, a ver cómo se decide a qué grupo de personas va cada vacuna si de aquí a verano puedes tener 7-8 entre las que elegir y ya en teoría, vacunados los grupos de riesgo.
De las que hay disponibles en Occidente o puede haber a corto plazo, todas utilizan la proteína de la espiga del virus para hacer la vacuna. Independientemente de si es de RNA mensajero, la secuencia genética está insertada en un vector adenoviral inactivado, o está hecha de subunidades proteicas. La eficacia puede variar de una a otra, pero tampoco creo que excesivamente, así como los posibles efectos adversos tanto a corto como a largo plazo, en caso de que existan. Alguna de las vacunas chinas sí inactivaban el virus completo (no usaban sólo la proteína de la espiga) con aluminio.SINVER escribió:
¿Alguna vez se ha vacunado contra alguna enfermedad con tantas variedad de vacunas a la vez?
Y al ser tan diferentes entre ellas, ARN, Adenovirus, etc. ¿No hay miedo que incitemos mutaciones adaptativas debido a que vamos a bombardear al bicho con diferente armamento pesado?
Sin tener ni **** idea de si eso es un problema, me pregunto, ¿alguien sabe si lo es?
No se, a mi es que me da que en vez de estar cada uno fabricando su vacuna, igual era mejor elegir una y que la fabricara todo el mundo, incluso el que no ha inventado una. Me imagino a Bayern, y otras farmaceúticas, con todo su potencial de fabricación mirando al tendido porque no han sacado su versión 2.0 del covidkiller y se me cae el alma a los pies.
Sí, claro. Se sumará aparte de las 5 que ya han publicado resultados.Joe barry carrol escribió:A qué te refieres con que solo se sumará CureVac? No habrá J&J o Noavax aquí?goupri escribió:De aquí a verano a priori y en caso de que salga bien solo se sumará CureVac (mRNA).Green Eyes escribió:Je, pues en esta carrera por tener vacunas y vacunar a cuanta más gente mejor y tener más dosis, a ver cómo se decide a qué grupo de personas va cada vacuna si de aquí a verano puedes tener 7-8 entre las que elegir y ya en teoría, vacunados los grupos de riesgo.
Tener varias vacunas para la misma enfermedad no es ningún problema, es algo que ya pasa en otros casos, y no hay evidencias de que la diversidad en la vacunación esté relacionada con la aparición de variantes más agresivas o infecciosas del SARS-CoV-2 u otros virus.SINVER escribió:Sin tener ni **** idea de si eso es un problema, me pregunto, ¿alguien sabe si lo es?
Virulence evolution in response to vaccination: The case of malaria"The relationship between herd immunity and antigenic drift has a clear implication for devising vacci-nation strategies: that vaccinating too many people can have negative consequences. Because of influenza’s effect on morbidity and mortality during annual epidemics, it would be imprudent to vaccinate fewer people with the hope of reducing antigenic drift. However, in seasons when high numbers of vaccines are administered, or almost equivalently, during seasons when we suspect natural host immunity to be quite high against the circulating strains, we should expect the emergence of immune-escape variants since the evolutionary pressure favoring them is strong. The case can be made that monitoring efforts should be strengthened during these seasons."
Éste artículo periodístico es bastante bueno y claro:"Are there any examples in other pathogens where vaccines have driven the pathogen towards higher virulence? Vaccines against smallpox, measles and polio have been outstandingly successful. These vaccines induce near-sterilising immunity. On the other hand, for diseases where vaccines are leaky, so that wild-type pathogens transmit and thus evolve through immune people, changes in pathogen virulence following vaccination have been documented, such as diphtheria, pneumococcal disease and whooping cough (pertussis). While these examples demonstrate that pathogen evolution in response to vaccines can happen, the effects on virulence are extremely difficult to determine because comparisons of virulence are very difficult without contemporaneous experimental infections with the different pathogen strains. For many animal diseases, where such experiments can be done, successful vaccines are frequently leaky. There are clear examples from the poultry industry of substantial increases in virulence following the widespread introduction of vaccines to both Marek's disease and Infectious Bursal Disease. These cases have all the hallmarks of vaccine-driven generalised virulence evolution. However, experimental analysis of their V–T–P relationships is still required to determine whether vaccination was indeed the cause. The subsequent history of the myxoma virus evolution demonstrates the role host resistance can also play in driving virulence evolution. As wild rabbits evolved greater resistance to myxomatosis, the virus evolved greater virulence"
* Este estudio es bastante complejo y muy interesante (necesitaría leerlo con detenimiento y probablemente varias veces):"All prime-boost regimens elicited high levels of SARS-CoV-2 spike-specific antibodies with neutralisation capacity and high avidity, levels that were greater than single vaccines alone."
"In vitro evolution is a tool to directly select for higher affinity binding. Here we show that the same mutations selected by nature, S477N, E484K, and N501Y were among the first to be selected by yeast surface display affinity maturation against ACE2. Moreover, the E484K, N501Y variant was the tightest binding mutation emerging from the B3 library. These two mutations evolved independently, but quite rapidly merged into single clones (...) Q498R was first observed in library B4, but established itself only in B5. This mutation emerges only together with N501Y, suggesting an epistatic effect between the two mutations. Indeed, deep-mutational scanning of single RBD mutations 6 showed Q498R to negatively affect both protein stability and binding, while we show that in combination with N501Y binding affinity is improved by ~4-fold above N501Y alone (...) This suggests that with the spread of the “British”, “Brazilian”, and “South African” variants, we project that the Q498R mutation will appear in the future, on top of these mutations. The synergism of Q498R with N501Y and E484K increases ACE2 binding by ~50-fold relative to WT. Another mutation projected to follow is N460K, which emerged late in yeast display. These mutations are located in a hyper-variable region of the RBD (Fig. S11), suggesting that their appearance is not constrained."
"From the similarity to yeast display selection, where stringent conditions are used, one may hypothesize that stringent selection is also driving the rapid spread of these mutations. Abundant low-quality face masks may provide one such selection condition, as they reduce viral titer, but not sufficiently."
"The RBD-62 has the potential as a drug, as it blocks ACE2 with very high affinity, while preserving the ACE2 functionality. It completely inhibited SARS-CoV-2 infection of VeroE6 cells, at low nM concentration (...) The main advantage of blocking ACE2 is that it is not directly affected by viral escape mutations, which constantly evolve."
¡La Sputnik despega!
Se acaba de publicar en The Lancet un análisis provisional de los datos del ensayo en fase III de la vacuna rusa, que confirma una eficacia del 92% incluso en personas mayores de 65 años.
https://www.thelancet.com/journals/lanc ... 8/fulltext
Ensayo con 20 000 participantes, 15 000 recibieron la vacuna y 5 000 el placebo. A los 21 días de la primera dosis se confirmaron 16 casos de Covid en el grupo de la vacuna y frente a 62 casos en el grupo placebo. En el grupo de la vacuna todos los casos fueron leves, mostrando un 100% de efectividad frente a casos moderados o graves.
Tampoco se observan efectos adversos importantes, más allá de algún caso de fiebre o cansancio.
La Sputnik consta de dos dosis, la primera utiliza como vector el adenovirus-26, modificado genéticamente para expresar la proteína de espiga del SARS-CoV-2, se trata del mismo vector utilizado por la vacuna de dosis única de Johnson & Johnson que declara una eficacia del 66%.
La segunda dosis utiliza como vector el adenovirus-5 modificado de igual forma que el anterior y que parece elevar la eficacia de la primera dosis hasta ese 92%.
Las vacunas basadas en adenovirus humanos, como el Ad-5, tienen el problema de la inmunidad preexistente, ya que nos infectan desde la infancia siendo responsables de algunos resfriados. Esta inmunidad puede provocar el ataque del sistema inmune al vector antes de lograr su objetivo. El uso del Ad-26 tanto en Sputnik como en J&J es un acierto ya que no se ven tan afectados por dicha inmunidad. Este problema puede bajar de forma importante la eficacia de la vacuna fabricada por CanSino, al utilizar exclusivamente como vector el Ad-5.
Por otro lado, merece la pena comentar que las vacunas basadas en adenovirus, aunque utilizan ADN que debe penetrar en el núcleo celular, carecen de mecanismos para integrarlo en el genoma y en ningún caso pueden producir enfermedades a largo plazo.
Va quedando más claro que esta vacuna protege y es segura. Sus beneficios son muy superiores a los riesgos frente a un virus mortal que además está dejando importantes secuelas entre las personas que logran superarlo.
Lo más aconsejable es aprovechar la vacuna que primero nos llegue, aunque no sea la más eficaz, con toda seguridad nos protegerá de una Covid moderada o grave que puede poner en peligro nuestra salud o incluso nuestra vida.
¡Un abrazo y cuídense!
"The article “The proximal origin of Sars-coV-2” (Andersen et al. 2020) is recurrently put forward as a proof for the natural origin of SARS-CoV-2. However, their reasoning does not rely on an actual positive proof of the zoonotic origin. Indeed, as discussed above, the divergence between RaTG13 and SARS-CoV-2 dates from several decades and we still do not know any suitable candidates for the animal hosting the proximal viral strains. Rather, the rationale of this article consists in opposing two mutually exclusive options, which are implicitly considered as exhaustive: either a “natural proximal origin” (i.e., a recent zoonosis), or a virus intentionally designed on the basis of prior knowledge, and constructed by reverse engineering (design hypothesis). They provide two arguments against the design hypothesis (the prior knowledge was insufficient to conceive the RBD, and there is no trace of reverse engineering in the genome) and thus conclude that the virus must be of natural origin. This reasoning is, however, flawed, because it restricts the choice to a dichotomy, whereas several other hypotheses are conceivable. In particular, the authors discard the possibility that the virus would result from laboratory selection through successive passages between animal species or cells, because they consider that the pangolin hypothesis is more parsimonious. However, these two hypotheses are so different that they cannot be evaluated in terms of maximum parsimony. They should rather be compared on the basis of their respective likelihood, but these would currently be very difficult to estimate, in the absence of key information in particular on the precise experiments performed in China on closely related viruses before the pandemic. Besides, the pangolin hypothesis has now been strongly questioned (Lee et al. 2020; Choo et al. 2020; Frutos et al. 2020). Regarding the hypothesis of reverse engineering, even though it is not obvious to identify any trace a posteriori there are currently several traceless options for genetic engineering. In conclusion, the arguments supporting the natural proximal origin are so far inconclusive and, albeit this hypothesis has been widely supported by the scientific community (Calisher et al. 2020), alternative hypotheses about a possible laboratory origin cannot be formally ruled out (Relman 2020). This question should thus be reopened, and all the hypotheses should be evaluated and weighted according to the different elements of information at our disposal."
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