Covid-19 vaccines and vaccinations

https://www.nature.com/articles/d41586-021-02054-z

Many vaccines have been shown to provide strong protection against COVID-19. Now, growing evidence finds that they also substantially reduce the risk of passing on the virus SARS-CoV-2 — crucial information for governments making decisions about how best to control the pandemic.

However, the studies were done before the highly transmissible Delta variant became prevalent — and scientists say it might be more easily spread by vaccinated people than are earlier variants.

Two studies1,2 from Israel, posted as preprints on 16 July, find that two doses of the vaccine made by pharmaceutical company Pfizer, based in New York City, and biotechnology company BioNTech, based in Mainz, Germany, are 81% effective at preventing SARS-CoV-2 infections. And vaccinated people who do get infected are up to 78% less likely to spread the virus to household members than are unvaccinated people. Overall, this adds up to very high protection against transmission, say researchers.

The studies reflect population-level trends, say researchers. “It’s good news,” says Natalie Dean, a biostatistician at Emory University in Atlanta, Georgia. “But it’s not quite good enough,” she notes, because it means that vaccinated people can still occasionally spread the infection.

And the highly transmissible Delta variant is a major source of uncertainty. The Israeli studies and others are based on the circulation of earlier variants, in particular Alpha, but research suggests that vaccines offer slightly reduced protection against Delta.
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What I am seeing out of Israel is a massive reduction in Pfizer's protection against infection over time. At six months its mostly gone, at under 20%. This is because of loss of antibody protection. What remains is T cell immunity, which is very long lasting. This is why severe disease, hospitalization and death is not worsening much with Delta and those vaccinated with Pfizer. Moderna may have a similar response. Its less sure about others, but quite likely.

Circulating antibodies are an instant defence. T cells take a bit of time. That instant defence does not last, but the slower protection from T cells might last decades, we just don't know.

To maintain antibody defence its very likely we will all need annual booster shots. This will also boost T cell immunity.
 
alex3619 said:
What I am seeing out of Israel is a massive reduction in Pfizer's protection against infection over time. At six months its mostly gone, at under 20%.
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I don't think those figures are credible. They are not the result of test-negative case control studies like the Canadian and UK data.

There are suggestions that those figures may be artifacts due to some errors and lack of matching exposure rates with suitable controls.



At 6 months, efficacy drops to the equilibrium levels as antibody levels flatten out - this is far higher than 0 or 20% protection against symptomatic infection.

Note that hospitalisation data still shows 95%+ effectiveness.
 
As I posted in another thread:

R effective = Rz (reduction in transmission of breakthrough cases * proportion vaccinated + proportion unvaccinated)*(proportion vaccinated (1-Vaccine efficacy against symptoms) + proportion unvaccinated)

Rz is the effective R for various social restrictions other than vaccination - if there are no restrictions, then Rz=R0, which is often quoted to be 5 for delta)

The goal is R effective < 1 means the outbreak will be self-limited.

This sort of model also assumes that transmission from true asymptomatic cases is very rare, which is empirically justified.

Many models have been assuming a 40-50% reduction in transmissibility of breakthrough cases. If the rate is actually 78+% then this is excellent news. If the rate is 0%, then population vaccination rates need to be 10-15% higher.
 
Merged thread
Co-infection waning in double jabbed

By Michelle Roberts
Health editor, BBC News online

Researchers say they are seeing some waning of protection against Covid infections in double-jabbed people.

The real-world study includes data on positive Covid PCR test results between May and July 2021 among more than a million people who had received two doses of Pfizer or AstraZeneca vaccine.

Protection after two shots of Pfizer decreased from 88% at one month to 74% at five to six months.

For AstraZeneca, the fall was from 77% to 67% at four to five months.

Waning protection is to be expected, say experts.

Although some breakthrough infections may be happening, vaccines are still doing a very good job at protecting people against severe Covid illness and deaths.

Vaccines saving lives

Public Health England estimates that around 84,600 deaths and 23 million infections have been prevented as a result of the Covid-19 vaccination programme in England so far.

Prof Tim Spector, lead investigator on the Zoe Covid Study app behind the research, said the findings could explain recent breakthrough infections that some fully vaccinated people have been reporting.

More at Covid infection protection waning in double jabbed - BBC News
 
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from article:

Prof Spector said: "Many people may not need them. Many people may have had a natural booster because they've already had a natural Covid infection, so will effectively have had three vaccines.

"So I think the whole thing needs to be much more carefully managed than just giving it to everybody which would be a huge waste and ethically dubious given the resources we have. I think we need a more targeted approach than last time."
 
Prof Spector :

"So I think the whole thing needs to be much more carefully managed than just giving it to everybody which would be a huge waste and ethically dubious given the resources we have. I think we need a more targeted approach than last time."

I have heard of people who have an active infection have tests come back as negative.

I personally know someone who became infected within two months of the double jab.

Given that those who had the jabs first are also the most vulnerable to infection - almost any respiratory infection - then these are the very people who would still be the mkst likely to suffer complications even from a milder version of covid.

As the effects of the jabs might be waning we are also approaching the flu season again when the NHS seems to struggle at the best of times.

So I'm not sure we have the capability to be more "targeted" currently. Even if it is viable it might be much more expensive than simply giving people a booster.
 
As usual, I can't find a clear UK page which explains the different types of test, so had to settle for this US one:

Types of tests
COVID-19 tests are available that can test for current infection or past infection.

  • A viral test tells you if you have a current infection. Two types of viral tests can be used: nucleic acid amplification tests (NAATs) and antigen tests.
  • An antibody test (also known as a serology test) might tell you if you had a past infection. Antibody tests should not be used to diagnose a current infection.
from Testing for COVID-19 | CDC
 
I'm not sure whether that's in response to my post @MeSci. Just in case it is in reply to -

Invisible Woman said:
I have heard of people who have an active infection have tests come back as negative.
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This person did have the correct test for an active infection. They were regularly having lateral.flow tests which flagged a positive then did a PCR test which was negative. As the PCR was negative it was assumed they didn't have an active covid infection. This was incorrect - they did have an active infection at the time.

TESTING
The tests commonly available for SARS-CoV-2 can detect either:

  • the RNA − detected by the PCR test
  • the surrounding proteins − detected by the rapid lateral flow devices
  • the human body’s response to the virus – detected by antibody tests.
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WHEN SHOULD I HAVE A PCR TEST?
  • If you currently have symptoms that may indicate COVID-19, this is the test you should have to diagnose the infection.
  • If a lateral flow test is positive. The purpose of the PCR test is to confirm the diagnosis, since it is a more accurate test than the lateral flow test.
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The quotes are from the Royal College of Pathologists website. There's a lot more information on which test to use when and so forth -

https://www.rcpath.org/profession/c...covid-19-tests-for-members-of-the-public.html
 
perchance dreamer said:
Are the research and recommendations for vaccine boosters coming from sources other than vaccine manufacturers?
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Yes, there are studies ongoing in the UK. The trouble is that it's not easy to draw clear inferences from waning antibodies alone (they're not our only defence against infection), but on the other hand, there are people who're extremely vulnerable because they have low immunity, and when it comes to them, we don't just want to wait for data on how many people get reinfected and how many of those get seriously ill.
 
It was reported in the Canadian news a few days ago that the Moderna vaccine produces more antibodies than the Pfizer vaccine. There is three times as much mRNA in the Moderna than the Pfizer vaccine. They are finding in seniors that had the Moderna that they have much higher levels of antibodies when tested compared to seniors who had the Pfizer vaccine around the same time.
 
Kitty said:
Yes, there are studies ongoing in the UK. The trouble is that it's not easy to draw clear inferences from waning antibodies alone (they're not our only defence against infection), but on the other hand, there are people who're extremely vulnerable because they have low immunity, and when it comes to them, we don't just want to wait for data on how many people get reinfected and how many of those get seriously ill.
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Good to know, thanks. I'll feel better having the extra protection of the booster, especially since there are still so many people refusing vaccines and masks. I don't see that changing.
 
perchance dreamer said:
Good to know, thanks. I'll feel better having the extra protection of the booster, especially since there are still so many people refusing vaccines and masks. I don't see that changing.
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Thankfully here in BC as of today everyone has to wear masks again when in public places including transportation. It never made sense why they were so quick to abandon masks when we could see that numbers were going up in other countries.
 
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Binkie4 said:
JCVI has just approved an additional vaccine dose for severely immunosuppressed people over the age of 12.

https://www.medscape.com/viewarticl...901_MSCPEDIT&uac=324782FT&impID=3608476&faf=1

edit: this is separate to an expected autumn vaccine campaign. Does that mean that some of us will be advised to have 4 covid jabs in less than a year? Side effects?
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I read about this earlier this morning and my take on it was that immunocompromised people would get the third vaccine ahead of everyone else. So it would be three vaccines, not four.
 
TigerLilea said:
I read about this earlier this morning and my take on it was that immunocompromised people would get the third vaccine ahead of everyone else. So it would be three vaccines, not four.
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From the above


"This is separate to an expected general autumn booster programme."

"Severely immunosuppressed people would still likely be offered a booster dose some weeks after their third dose."
 
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