A preprint in the Lancet https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3777268   details additional vaccine trial data from Astra Zeneca. it differs from the previous work in that participants were studied for a further month  during which primary symptomatic infections rose from 131 to 322. Data pertain to trials in the UK, Brazil and South Africa and are taken two weeks post second shot. Primary symptomatic infection means PCR+ and at least one of a range of symptoms like fever more than 37.8oC, cough, .....

Briefly summarizing the results (I exclude the low dose-standard dose data as this regime is apparently not pursued anymore): 

1. With the standard two shot protocol (4 week interval between shots), efficacy was 63.1% - similar to the previous result of ca 62%- in preventing symptomatic cases There were 7,200 participants in both vaccinated and placebo groups with 74 and 197 cases, respectively.

2.Vaccination had no effect in preventing asymptomatic cases.

3. Based on any PCR+, efficacy was 49.5%.

Note that there is an 'exclusion period' of three weeks, meaning that people who tested positive in the first 21 days after their first shot are excluded from the results!

 

In smaller groups (around 900-1,300 persons each, tested in UK only), first shot was followed by a second after more than 6 weeks and up to more than 12 weeks.

1.Efficacy for preventing primary symptomatic cases increased from  59.9% to 82.4% for the longest interval (i.e. at least 12 weeks). For the 12+ weeks interval there were ca 1,300 participants in both vaccinated and placebo groups and 8 and 45 cases, respectively. 

2. Efficacy in preventing asymptomatic cases varies enormously, but as lower CI in all cases is far below zero, data are meaningless.

 

No severe cases in vaccinated groups.

There are a lot more data, including antibody levels, etc.

Cut-off for the data was early December, meaning that most of the data presumably pertain to the  'older' virus variants.

Seems to indicate the vaccine is very good at preventing severe illness, yet has little effect in preventing transmission of the virus,it would be interesting to see if the transmissions post vaccine prevent severe illness.

https://www.independent.co.uk/news/health/oxford-covid-vaccine-study-dose-b1796549.html

 

The take away is quite different :

 

 

The Oxford coronavirus vaccine offers 76 per cent protection for up to 12 weeks after the administration of a first dose, new analysis suggests.

Researchers at the University of Oxford said their vaccine may also reduce transmission of the virus by 67 per cent.

 

11 minutes ago, FarFlungFalang said:

Seems to indicate the vaccine is very good at preventing severe illness, yet has little effect in preventing transmission of the virus,it would be interesting to see if the transmissions post vaccine prevent severe illness.

 

The study suggests that under optimal dosing prevention of transmission may be 67%.

 

 

19 minutes ago, mommysboy said:

The take away is quite different :

 

 

The Oxford coronavirus vaccine offers 76 per cent protection for up to 12 weeks after the administration of a first dose, new analysis suggests.

Researchers at the University of Oxford said their vaccine may also reduce transmission of the virus by 67 per cent.

 

 

The study suggests that under optimal dosing prevention of transmission may be 67%.

 

 

The data I quoted are from Table 1 in the Lancet article: efficacy after two doses because ultimately that is how the regime will be. The data you quote from the independent are from Table 2: efficacy after one shot: this was 76% against symptomatic infection or 67% against any PCR+ after a single shot. There seems to be a large discrepancy between Tables 1 and 2 but between 90 and 120 days after a single dose the efficacy dropped dramatically from ca 73-78% to  only 32% but due to low number of cases, the statistics are horrible. 

11 minutes ago, cormanr7 said:

The data I quoted are from Table 1 in the Lancet article: efficacy after two doses because ultimately that is how the regime will be. The data you quote from the independent are from Table 2: efficacy after one shot: this was 76% against symptomatic infection or 67% against any PCR+ after a single shot. There seems to be a large discrepancy between Tables 1 and 2 but between 90 and 120 days after a single dose the efficacy dropped dramatically from ca 73-78% to  only 32% but due to low number of cases, the statistics are horrible. 

 

Under the current  standards used for the AZ standard trial, Pfizer, etc, the efficacy test is against symptomatic infection.

 

Using the optimal dosing regime now being used in the UK:

 

76% first shot.

82% after second dose.

 

Previous data was used to secure approval, but the time-frame between doses has proved to be a sub-optimal regime.

 

Efficacy is expected to drop in line with other vaccines when encountering the UK and SA variant.

 

Latest data on older people yet to be published has been described as 'very reassuring'.

 

The UK appears to have been vindicated in regard to its controversial dosing strategy in regard to the AZ vaccine, which is very effective as stated.

 

 

 

 

The idea of delaying a second dose arose for a couple of reasons, AZ's efficacy issues with dose interference and supply issues for all vaccines. Now there are serious concerns from those who track the viruses' rapidly rising mutations.

 

Multiple sources warn that people who are partially vaccinated, due to delayed second doses or lower efficacy vaccines like Sinovax, raise the risk of increased mutations, particularity ones that can 'breakout' from the body's immune barrier. This is seen for both natural immunity from the disease as in Brazil and for vaccines as seen in South Africa.

 

Delayed Vaccine Doses and the Potential for Mutation

UK Delay of Second COVID-19 Vaccine Dose – A Risky Strategy

Coronavirus: The dangers of weak vaccines

Fauci: delaying second COVID-19 vaccine doses could spread mutant virus variants

 

They see cases of similar mutations arising independently, which suggests the mutations are 'purposeful'. Some of these variants consist of many simultaneous mutations, the UK variant had 20. They suggest this can happen in patients under strong treatment or with partial immunity.

 

17 minutes ago, rabas said:

 

They see cases of similar mutations arising independently, which suggests the mutations are 'purposeful'. Some of these variants consist of many simultaneous mutations, the UK variant had 20. They suggest this can happen in patients under strong treatment or with partial immunity.

 

Well, mutations are supposed to be random, most fizzle out but if a variant occurs that spreads 50% or whatever faster than the dominant strain at that moment it will take over all other things being equal. This has happened with the Kent strain in the UK, Ireland and Portugal to name a few. Mutations tend to be gradual but many virologist were shocked by how fast the Kent variant spreads. Then we have other, potentially even more troubling variants such as those from S Africa and Brazil. And they won't be the last.

Poor vaccines or partial protection will increase the chance that a mutation will overcome a poor immune response.

The present day vaccines are largely based on the original spike protein/whole virus sequence from Wuhan but the recent Novavax results has shown that this does not work too well against new variants. Vaccine producers brush this away by claiming that they can quickly adapt their vaccines but I think they will behind the curve.  So there is some unease at the moment

https://www.bbc.com/future/article/20210119-covid-19-variants-how-the-virus-will-mutate-in-the-future

 

I read the first 6 posts 3 times and still don't understand this mess. 

3 hours ago, cormanr7 said:

There seems to be a large discrepancy

It's just as messy as were their first study results?

Anyway,  those "90% efficacy if first dose only half strength" quietly evaporated?

AZ really seems to be not good at clinical studies, statistics and communicating results.

 

Hopefully we can trust them that their DNA vaccine is "not incorporated into the (human genome) DNA from what  AstraZeneca says".

https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3D35Idb_lCU4o&ved=2ahUKEwi91Ken-czuAhUCxosBHWflC4sQFjAAegQIARAB&usg=AOvVaw0Yl1GzkAqb38QMtYZK8fjq&cshid=1612329019455

 

Somehow this convoluted mess fits to the fact that the 3 letters "DNA" are so painstakingly avoided when people propagate AZ. "It's a vector vaccine". Vector means vehicle. What's transported in the vehicle? DNA. Psssst!

 

Some journalists and medical professionals even call AZ a "traditional" or "conventional" kind of vaccine that has been used for years. That's true - in animals.  In humans this technique has been used for 3 (three) years,  against Ebola. So, yes, three years is " years" , technically this is not a lie. But to call it "conventional" or "traditional" is a lie.

 

Conventional vaccines are the Chinese ones. Which doesn't mean I trust them. 

6 minutes ago, Kiujunn said:

AZ really seems to be not good at clinical studies, statistics and communicating results.

 

Too honest given the timescale. Honesty, if not exactly what is expected, is better than potential miss information. It is not a perfect world. 

Self-efficacy may not be the correct term in this case but it is a British trait and may not be understood by all.