Results of Covid/Vaccine Studies

[Chuckanut]

Here's a paper published by Public Health England regarding the effectiveness of two vaccines (Pfizer-BioNTeach and Astra Zenica) and their effect on the population.

https://assets.publishing.service.g...193/Vaccine_surveillance_report_-_week_20.pdf

It appears to be a compilation of various studies and trials from December 8 to May 16.

The data in this week’s report covers the period from 8 December 2020 to 16 May 2021(Figure 5). It shows the provisional number and percentage of people in England who have had received 1dose or 2 doses of a COVID-19 vaccination by age group and week since the start of the programme.

Compared to unvaccinated, vaccine effectiveness for 1dose was estimated at 54% (95% CI 50-58%) for the Pfizer-BioNTech vaccine and 53% (95%CI 49-57%) for the Oxford-AstraZeneca vaccine. Compared to 4to 13 days post vaccination, this was 57% (95%CI 53-61%) and 58% (95%CI 54-62%) respectively.

After 2 doses, effectiveness was estimated as 90% (95%CI 82-95%) for the Pfizer-BioNTech vaccine and 89% (95%CI 78-94%) for the Oxford-AstraZeneca vaccine compared to unvaccinated. Compared to 4to13 days post vaccination,this was 91% (95%CI 83-95%) and 90% (95%CI 80-95%) respectively.

With the Pfizer-BioNTech vaccine there is a small reduction in vaccine effectiveness from 10 weeks after the first dose. This may be explained by some waning of protection or by biases due to differences in the earliest groups who were vaccinated compared to later groups. There is no evidence of this waning effect with the Oxford-AstraZeneca vaccine.

Note: Table 1. It's very interesting.

Going through the document confirms that while the vaccines are very effective in some areas, there are areas that need further study. More information is needed to increase the level of certainty. The authors appear to be taking a very conservative approach to evaluating the vaccines. I like that careful approach.

 

[Sojourner]

Very interesting. Based on the second quote above, it appears the AZ vaccine is essentially just as effective as the Pfizer-BNT vaccine, which is definitely news to me. I thought the mRNA vaccines (Pfizer-BNT and Moderna) were the clear winners versus more traditional vaccine platforms, like the AZ viral vector (using a modified chimpanzee adenovirus). Certainly, the impression I've gotten from various media reports has been that AZ was inferior to the mRNA vaccines against some of the more well-known variants.

Looking forward to reading the whole paper to dig into more of the details. Thanks for posting this, OP.

 

[jcfradio]

Vaccine Options

Up here in Canada, our government has gone to a 16 week interval between first jab and second jab, in order to get as many people as possible vaccinated with their first shot. I had my first shot with AstraZeneca in mid March. I now have the option of getting a second jab next week with AZ or waiting and taking my chances on getting a Pfizer jab in 2 months (no guarantee, since they might say that if you have a first AZ shot, you can only get a second shot also from AZ). I am not concerned about the blood clot question, but more about the uncertainty of whether going to the second mechanism to get better protection against future variants. What would you do?

 

[Alan]

Thanks for posting this report, I'd seen various bits of it reported on the TV but not seen the whole study.

As you say, table 1 is a good summary. The Pfizer vaccine was in use a full month before the AZ vaccine hence lack of data for the effectiveness of the AZ second dose at this point. In the UK the doses have been separated by 12 weeks which is also a factor in lack of 2nd dose data for the AZ vaccine. Recently the gap has been shortened to 8 weeks.

 

[Alan]

threads merged

 

[Alan]

Up here in Canada, our government has gone to a 16 week interval between first jab and second jab, in order to get as many people as possible vaccinated with their first shot. I had my first shot with AstraZeneca in mid March. I now have the option of getting a second jab next week with AZ or waiting and taking my chances on getting a Pfizer jab in 2 months (no guarantee, since they might say that if you have a first AZ shot, you can only get a second shot also from AZ). I am not concerned about the blood clot question, but more about the uncertainty of whether going to the second mechanism to get better protection against future variants. What would you do?

My wife and I are currently in a second trial of mixing vaccines, AZ or Pfizer mixed with Moderna or Novavax.

Earlier trials in the UK and Spain of mixing AZ with Pfizer is producing some good preliminary results.

https://www.nature.com/articles/d41586-021-01359-3

Vaccinating people with both the Oxford–AstraZeneca and Pfizer–BioNTech COVID-19 vaccines produces a potent immune response against the virus SARS-CoV-2, researchers conducting a study in Spain have found.

Preliminary results from the trial of more than 600 people — announced in an online presentation on 18 May — are the first to show the benefits of combining different coronavirus vaccines. A UK trial of a similar strategy reported1 safety data last week, and is expected to deliver further findings on immune responses soon.

The chances of adverse reactions in mixing AZ and Pfizer is increased.

https://www.cnbc.com/2021/05/12/cov...ines-increases-risk-of-adverse-reactions.html

In a peer-reviewed research letter published in The Lancet international medical journal on Wednesday, researchers of the trial reported that when given at a four-week interval, both of the alternating vaccine schedules of the Oxford-AstraZeneca vaccine and the Pfizer-BioNTech vaccine induced more frequent reactions following the second dose than the standard non-mixed schedules.

“Whilst this is a secondary part of what we are trying to explore through these studies, it is important that we inform people about these data, especially as these mixed-doses schedules are being considered in several countries,” Matthew Snape, associate professor in Paediatrics and Vaccinology at the University of Oxford, said in a statement.

 

[Alan]

The variant first detected in India has been of big concern in the UK this past few weeks after surges of Covid in places like Blackburn, Bolton, Bedford and Glasgow. The good news is that a recent study shows that the current vaccines offer good protection against it provided both doses have been received.

https://www.msn.com/en-gb/health/me...riant-of-coronavirus-study-reveals/ar-AAKid5J

Both the Pfizer and AstraZeneca jabs were found to be almost as effective against symptomatic disease from the B1617.2 strain as they are against the Kent variant after the second dose.

However, they were only 33 per cent effective three weeks after the first dose.

Health Secretary Matt Hancock described the outcome as "groundbreaking", while PHE said it expects to see even higher levels of effectiveness against hospital admission and death.

The study, which took place between April 5 and May 16, found that the Pfizer vaccine was 88 per cent effective against symptomatic disease from the Indian variant two weeks after the second dose, compared with 93 per cent effectiveness against the Kent strain.

Meanwhile, the AstraZeneca jab was 60 per cent effective, compared with 66 per cent against the Kent variant over the same period.