Friday, October 22, 2021

Scottish study: Vaccines '90% effective' at preventing Delta variant deaths

Vaccination is 90% effective at preventing deaths from the Delta variant of Covid-19, researchers say. The data, released by the University of Edinburgh, was gathered using a Scotland-wide Covid surveillance tool.

Figures suggest the Pfizer-BioNTech vaccine is 90% effective and the Oxford-AstraZeneca jab 91% effective at preventing deaths.

It looked at people who have been double-vaccinated but who have tested positive for Covid in the community.

The study is the first to show across an entire country how effective vaccines are at preventing death from the Delta variant, which is the most dominant form of Covid in the UK.

Researchers defined death from Covid as anyone who died within 28 days of a positive PCR test, or with Covid recorded as a cause of death on their death certificate.

The study analysed data from 5.4 million people in Scotland between 1 April and 27 September this year.

During this period, 115,000 people tested positive for Covid using a PCR test in the community, rather than in hospital, and there were 201 Covid-related deaths recorded.

Tracked in real time

No deaths have been recorded in those who have been double-vaccinated with the Moderna vaccine in Scotland, according to the data.

Researchers said it is therefore not possible to estimate this particular vaccine's effectiveness in preventing Covid-related deaths.

The research team from the University of Edinburgh, University of Strathclyde and Public Health Scotland analysed the dataset as part of the EAVE II project - Early Pandemic Evaluation and Enhanced Surveillance of Covid-19.

It uses anonymised, linked-patient data to track the pandemic and the vaccine rollout in real time.

Age groups second dose

So far, 87.1% of adults in Scotland have taken a second dose of the Covid vaccine.

Third "booster" doses are being offered to everyone over 50, along with frontline medical staff and younger adults with some underlying health conditions.

Prof Aziz Sheikh, director of the University of Edinburgh's Usher Institute and EAVE II study lead, said: "With the Delta variant now the dominant strain in many places worldwide, and posing a higher risk of hospitalisation than previous variants seen in the UK, it is reassuring to see that vaccination offers such high protection from death very shortly after the second dose.

"If you still have not taken up your offer to be vaccinated, I would encourage you to do so based on the clear benefits it offers."

Follow-up studies

Prof Chris Robertson, of the University of Strathclyde and Public Health Scotland, said: "This study shows the value of carrying out analyses of routine healthcare data available in near real-time.

"Our findings are encouraging in showing that the vaccine remains an effective measure in protecting both ourselves and others from death from the most dominant variant of Covid-19."

He added that it was important to validate these early results with follow-up studies.

The team behind the study said due to the observational nature of the figures, data about vaccine effectiveness should be interpreted with caution and said it was not possible to make a direct comparison between both vaccines.


England data: How are COVID vaccines faring against Delta?

New research, published in The New England Journal of Medicine, has confirmed that both AstraZeneca and Pfizer COVID vaccines have a lower efficacy against Delta, with a single dose of either vaccine around 30% effective against the strain, compared to 48% for the Alpha variant.

However, after two doses, only modest differences were observed, with Pfizer 88% effective against Delta compared to 93% for Alpha, and AstraZeneca 67% effective against Delta and 74.5% for Alpha.

So how is this playing out in the UK?

With Delta now the dominant strain, case numbers have started to soar, with more than 330,000 people testing positive in the past seven days. Hospitalisation rates have also started to increase, with 4510 people admitted between 8–14 July, up 38.6% on the previous seven days, and 366 deaths recorded between 15–21 July, up 59.8% from the past week.

That is with 69.1% of the adult population fully vaccinated and 88.1% having received one dose.

But infectious diseases physician and microbiologist Associate Professor Paul Griffin told newsGP that the findings are not unexpected as Delta is more infectious, and that the reduced efficacy is ‘not all that significant’.

‘We know people that are fully vaccinated can still get infected,’ he said.

‘But what we also know is that they’re, at least modestly, reduced in terms of their ability to transmit, and have very significantly reduced chances of getting really sick, being hospitalised and dying.

‘And, again, that doesn’t mean that the numbers of deaths will go to zero. Even if we had 100% of people vaccinated, there’d still be one or two people per 100, and there’d still be 10 people that do get sick – but it’s significantly reduced.

‘We just have to look at the proportion that get really sick, and make sure that that doesn’t jump up indicating that our vaccines are no longer working. But we’re clearly not at that point yet.’

In Israel, where Delta is causing a fourth wave, health officials are less certain.

The country’s Ministry of Health earlier this month lowered its projection of Pfizer being 95.3% effective to just 64% against Delta, and warned that it could be even lower, as about 90% of new confirmed cases in those aged over 50 are fully vaccinated.

However, it is worth noting that while case numbers have risen from zero on 5 June to 668 on 19 July, deaths have remained low, with only two recorded on 19 July.

With 85% of adults vaccinated in Israel, Associate Professor Griffin says that in and of itself could be why the proportion of cases who are vaccinated appear to be overrepresented, but that more information is needed.

‘It’s hard to know what those case numbers would have been had they not had so many people vaccinated,’ he said.

‘So, it’s not really, at this stage, data that lends itself to concluding that the vaccine performs less well there.

‘I think part of it is a bit of a skewing of the numbers. The key thing there will be looking at, again, the serious cases, hospitalisations, and deaths. If they truly climb there would be concern about the actual efficacy being less than we think.’

Comparing Delta waves in countries with a high proportion of vaccinated adults to those with low vaccination rates, also suggests current vaccines are effective at reducing hospitalisations and deaths.

Likewise, the UK research, funded by Public Health England, has concluded the findings support efforts to maximise vaccine uptake with two doses among vulnerable populations.

As children appear to be more susceptible to the Delta variant, a number of countries have already approved COVID vaccination in children, including Israel, the US, France and Italy, with the UK set to offer vaccination to those aged 12–15 who are at higher risk of COVID due to disability or illness.


Pfizer says COVID-19 booster shot showed high efficacy in large study

Berlin: A booster dose of the COVID-19 vaccine developed by Pfizer and German partner BioNTech restored efficacy to 95.6 per cent against the virus, including the Delta variant, data released by the companies from a large study shows.

The companies said in a press release that the trial, which has not been peer-reviewed, tested 10,000 participants aged 16 and older, and found that the booster shot had a favourable safety profile.

Dr Walid Gellad, a professor at University of Pittsburgh’s medical school, said there seems to be a benefit of having the third dose in the Delta wave for symptomatic COVID-19.

“I’m just still very curious if this is primarily in people who are much, much older. Because what we don’t want to do is run out and give boosters to 25-year-olds who had COVID before and got two doses of the vaccine, just based on this press release,” Gellad said.

Pfizer had said its two-shot vaccine’s efficacy drops over time, citing a study that showed 84 per cent effectiveness from a peak of 96 per cent four months after a second dose. Some countries had already gone ahead with plans to give booster doses.

The trial results come a day after the US Food and Drug Administration authorised booster doses of the COVID-19 vaccines from Moderna and Johnson & Johnson, and said Americans could choose a different shot from their original inoculation as a booster.

The agency previously authorised boosters of the Pfizer/BioNTech shot at least six months after the first round of shots to increase protection for people aged 65 and older, those at risk of severe disease and those who are exposed to the virus through their work.

The drugmakers said on Thursday, local time, the median time between the second dose and the booster shot or the placebo in the study was around 11 months, adding there were only five cases of COVID-19 in the booster group, compared with 109 cases in the group which received the placebo shot.

The median age of the participants was 53 years, with 55.5 per cent of participants between 16 and 55 years, and 23.3 per cent at 65 years or older.

Jefferies analyst Michael Yee said the trial results add to mounting data that boosters could help in providing long-lasting protection from symptomatic infection.

There were no reported cases of severe disease, suggesting robust protection from infection with only the primary vaccination series, Yee wrote in a note.

The companies said they would submit detailed results of the trial for peer-reviewed publication to the US FDA, the European Medicines Agency and other regulatory agencies, as soon as possible.




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