Scrutable

shpalman wrote: ↑

Mon Feb 08, 2021 6:54 pm

South Africa is going to roll out the AstraZeneca vaccine in steps to see if it actually works

Herainestold wrote: ↑

Tue Feb 09, 2021 12:27 am

shpalman wrote: ↑

Mon Feb 08, 2021 6:54 pm

South Africa is going to roll out the AstraZeneca vaccine in steps to see if it actually works

Cool. What is your prediction?

shpalman wrote: ↑

Tue Feb 09, 2021 7:07 am

Herainestold wrote: ↑

Tue Feb 09, 2021 12:27 am

shpalman wrote: ↑

Mon Feb 08, 2021 6:54 pm

South Africa is going to roll out the AstraZeneca vaccine in steps to see if it actually works

Cool. What is your prediction?

There will be a Hawthorne effect, rather than an effect of the vaccine.

Evidence that the coronavirus vaccines being deployed globally are dramatically effective in reducing severe disease and death in symptomatic Covid-19 is abundant. But a big question remains unanswered: can they thwart transmission, in other words stop people from passing on the virus?

To evaluate the impact of the vaccine on transmission, researchers compared data from people over 60 years old and those aged 40 to 60, evaluating data from 16,297 people who had tested positive for coronavirus between 1 December and 30 January.

Israel’s vaccine programme began on 20 December. By the time of analysis, more than 75% of those in the older group were likely to have received their first dose, as had about 25% of the younger group.

Although researchers did not know whether each person had been given their first vaccine dose, their hypothesis was that if the vaccine was reducing viral load, then evidence of that would begin to show up in late January but not before, because of the time required by the vaccine to stimulate the immune system.

As expected, in the last two weeks of January the researchers noted a statistically significant fall in the viral load for the individuals aged over 60, compared with the 40-to-60 group, said the study author, Yaniv Erlich, the chief scientific officer of MyHeritage, a company that runs a large coronavirus testing laboratory in Israel.

Of course, if we are to beat this virus altogether, we will need vaccines that prevent infection and transmission. It’s not yet clear if current vaccines will prevent people who have been vaccinated from transmitting the virus, even for the original variants of the virus. Phase 3 trials have been unable to demonstrate this. But there’s good reason to hope they will – not least because of reports that the AstraZeneca vaccine appears to reduce infections by 67%.

shpalman wrote: ↑

Wed Feb 10, 2021 11:25 am

Oh and that stuff at the end about being able to update vaccines quickly to deal with new variants in a regime of giving annual shots, well, not if your immune system quickly destroys the adenovirus vector which ChAdOx1 uses, which is the suggestion for why it doesn't even work to give two closely-spaced full doses of the vaccine once (and why Sputnik V for example uses different vectors for the two doses). So we'll have to see if after a year the body "forgets" the viral vector.

Grumble wrote: ↑

Wed Feb 10, 2021 10:26 pm

Serious question here: even if AZ doesn’t work against SA variant it’s worth getting for the protection against the other variants isn’t it? Even if a follow up needs to be done when it’s available.

Grumble wrote: ↑

Wed Feb 10, 2021 10:26 pm

Serious question here: even if AZ doesn’t work against SA variant it’s worth getting for the protection against the other variants isn’t it? Even if a follow up needs to be done when it’s available.

Israeli study finds 94% drop in symptomatic COVID-19 cases with Pfizer vaccine

South African Covid variant may cut Pfizer vaccine protection by two-thirds
Study finds fall in antibody activity – but scientists say jab should still protect against severe disease and death

A laboratory study suggests that the South African variant of the coronavirus may reduce antibody protection from the Pfizer/BioNTech vaccine by two-thirds, and it is not clear if the shot will be effective against the mutation, the companies have said.

The study found the vaccine was still able to neutralize the virus and there is not yet evidence from trials in people that the variant reduces vaccine protection, the companies said.

Still, they are making investments and talking to regulators about developing an updated version of their mRNA vaccine, or a booster shot, if needed.

shpalman wrote: ↑

Tue Jan 05, 2021 6:10 pm

ReiThera's GRAd-CoV2 vaccine passes Phase I

shpalman wrote: ↑

Tue Feb 02, 2021 7:10 pm

ox-new-Tab2.png

From https://papers.ssrn.com/sol3/papers.cfm ... id=3777268

Their Table 1 doesn't contradict the already-published results on the SD/SD and LD/SD regime.

A further important question is whether vaccines can reduce transmission, and therefore combined with physical distancing measures contribute to reductions in human-to-human transmission of the virus. Although transmission studies were not included in the analysis, swabs were obtained from volunteers every week in the UK study, regardless of symptoms, to allow assessment of the overall effect of the vaccine on risk of infection, and thus a surrogate for potential onward transmission. If there was no effect of a vaccine on asymptomatic infection (about a third of infections), it would be expected that an efficacious vaccine would simply convert severe cases to mild cases and mild cases to asymptomatic, with overall NAAT positivity unchanged. Overall NAAT positivity is appropriate to assess whether there is a reduction in the burden of infection. We showed that a single standard dose of the vaccine had efficacy against any NAAT-positive infection, including symptomatic and asymptomatic infections, of 63·9% between day 22 and 90 after first dose, and that, after the second dose, the two standard doses schedule had an efficacy of 49·5%. These data indicate that ChAdOx1 nCoV-19, used in the authorised schedules, might have a substantial effect on transmission by reducing the number of infected individuals in the population

“...if you could aim specifically to generate antibodies in the mucosal linings of the upper airways you could help block the virus from infecting someone or from being passed on,” said Adam Finn, professor of paediatrics at the Bristol Medical School, University of Bristol.

“In effect, you would be creating the anti-viral equivalent of those United Nations blue helmet soldiers who control war zones and prevent invasions.”