Covid-19 vaccines and transmission

(mRNA vaccines) Interim Estimates of Vaccine Effectiveness of BNT162b2 and mRNA
updated here: Coronavirus Disease 2019
91% protection against infection
(AZ vaccine) Covid-19: One dose of vaccine cuts risk of passing on infection by as much as 50%, research shows

Better, here's a summary of tons of studies, although a little out of date:
Coronavirus Disease 2019 (COVID-19)

Bottom line: yes, vaccines (especially mRNA vaccines) provide very good but not perfect protection against infection.

Isaiah 41:10 said:

And I guess it would be fair to say that if individuals aren't infected, then they also would not then be able to pass the virus along, by extension. Is this correct?

Click to expand...

Correct. I mean, there's a tiny chance you could touch something and get the virus on your hand and then shake hands with someone else who touches their eyes. But getting infected from surfaces seems to be uncommon with this virus, and adding an extra step in the process would make this an extremely unusual infection route.

Isaiah 41:10 said:

One idea I continually hear from opponents of vaccination is that these new vaccines, the Pfizer and moderna in particular, only remove or eliminate symptoms and hospitalization, but do not necessarily prevent infection, and more specifically transmission.

I was wondering what everyone's opinion is on this.

For proponents or supporters of vaccination:

1. What studies are we aware of in which either of these vaccines have truly prevented infection (not just symptoms)?

2. And further, what studies are we aware of in which transmission of covid-19 has been explicitly observed to be decreased as a product of vaccination?

Click to expand...

That's some really dumb argument they got. "I'm against the vaccines because they only save lives and keep people from getting sick.".

sfs said:

Correct. I mean, there's a tiny chance you could touch something and get the virus on your hand and then shake hands with someone else who touches their eyes. But getting infected from surfaces seems to be uncommon with this virus, and adding an extra step in the process would make this an extremely unusual infection route.

Click to expand...

What about the new more contagious variants? Are they more likely to be transmitted by touch as well as by air?

Strathos said:

What about the new more contagious variants? Are they more likely to be transmitted by touch as well as by air?

Click to expand...

There's not a lot of information available, at least not that I've seen. It's likely that transmission is likely to go up by any route, probably by comparable factors. The obvious ways of increasing transmissibility -- more virus being shed, people remaining infectious longer, better binding of the virus to cellular receptors -- aren't going to discriminate based on how the virus happens to reach you.

The main point about these vaccines is that they [significantly] reduce the chance of getting significantly sick with Covid. Although they reduce the chance of infection, they do not prevent it.

So the idea is that they reduce chance of infection, but should one get infected despite the vaccine (it happens everyday) the disease would be a lot less severe than otherwise.

Last week I was in a room with 5 other people. 4 fully vaccinated and 2 people with previous infections including myself. The other person with a previous infection caught COVID and he infected two fully vaccinated people that sat right beside him. The odds are high it was the delta variant but we do not know for sure. The one with the previous infection and one fully vaccinated person have recovered very well. The other fully vaccinated person continues to struggle with fever, fatigue, and cough. The two other fully vaccinated persons and myself have not gotten sick. We sat further away and had less contact with him.

So it seems that in our case it is uncertain whether or not vaccination had any help in symptom management and certainly had little to no effect in preventing infection in close contact persons (with delta). One can speculate that without vaccinations the two people who were vaccinated could have had worse symptoms but there is no evidence to say one way or another.

Also one of the vaccinated persons spread it to another person, so there is evidence that vaccinated persons can spread covid as well.

I am not for or against the vaccinations. Previously having covid and still testing positive for antibodies I saw no need in getting vaccinated until delta. I am still on the fence however as I have reservations with these points:

1. Not fully approved by the FDA. Still considered experimental.
2. Immunity for vaccine companies.
3. No understanding on long-term side effects from the vaccines. They say there are none but that is impossible to know.

If the FDA fully approves them and we are able to sue for damages I would probably get it.

Thats my 2.

stvns78 said:

Last week I was in a room with 5 other people. 4 fully vaccinated and 2 people with previous infections including myself. The other person with a previous infection caught COVID and he infected two fully vaccinated people that sat right beside him. The odds are high it was the delta variant but we do not know for sure. The one with the previous infection and one fully vaccinated person have recovered very well. The other fully vaccinated person continues to struggle with fever, fatigue, and cough. The two other fully vaccinated persons and myself have not gotten sick. We sat further away and had less contact with him.

So it seems that in our case it is uncertain whether or not vaccination had any help in symptom management and certainly had little to no effect in preventing infection in close contact persons (with delta). One can speculate that without vaccinations the two people who were vaccinated could have had worse symptoms but there is no evidence to say one way or another.

Also one of the vaccinated persons spread it to another person, so there is evidence that vaccinated persons can spread covid as well.

I am not for or against the vaccinations. Previously having covid and still testing positive for antibodies I saw no need in getting vaccinated until delta. I am still on the fence however as I have reservations with these points:

1. Not fully approved by the FDA. Still considered experimental.
2. Immunity for vaccine companies.
3. No understanding on long-term side effects from the vaccines. They say there are none but that is impossible to know.

If the FDA fully approves them and we are able to sue for damages I would probably get it.

Thats my 2.

Click to expand...

And this, folks, is useful, helpful information. Real-life experiences from people regarding the vaccine, the virus, and questions about both. Not studies, not numbers put out by news stations, but actual, real-life info.

stvns78 said:

So it seems that in our case it is uncertain whether or not vaccination had any help in symptom management and certainly had little to no effect in preventing infection in close contact persons (with delta). One can speculate that without vaccinations the two people who were vaccinated could have had worse symptoms but there is no evidence to say one way or another.

Click to expand...

An interesting anecdote, but as your recognize it is not worth much without a lot more data. Breakthroughs and reinfection are always possible, and expected at some rate, the vaccine works by making them less likely not impossible, Thus far the data indicates vaccine and prior exposure is prophylactic against severe infection which seems to be the case here. Getting vaccinated so as to minimize infection response and transmission still makes sense, but the delta variant seems more like what the original fears of transmission were. Good that it least came out later after we had a vaccine or a whole lot more places would look like NY and Italy in the beginning.

anna ~ grace said:

And this, folks, is useful, helpful information. Real-life experiences from people regarding the vaccine, the virus, and questions about both. Not studies, not numbers put out by news stations, but actual, real-life info.

Click to expand...

No it is not actually terribly useful, in cases like this, the information is only really useful when one has enough data to determine whether the situation is anomalous or a real trend. You don't stop driving just because one person you know had a car accident.

Isaiah 41:10 said:

@sfs do you know anything about the vaccines effectiveness vs the delta variant?

Click to expand...

The most widely reported, and probably the most trustworthy, study is this one, which found that 2 doses of Pfizer were 88% effective against symptomatic disease. A press release also reported 96% effectiveness against hospitalization, but the published study says they don't have statistical power to assess that. Other studies that I haven't looked at have reported similar numbers, while one study from Israel reported sixty-some percent effectiveness, but that study's methodology has been criticized (and I think it was funded by Pfizer, which has a financial interest in booster shots). The 88% value is about 5% lower than for the alpha variant.

I've also seen the number 80% for protection against infection but I haven't run the source to ground (and probably don't have time to do so).

anna ~ grace said:

And this, folks, is useful, helpful information. Real-life experiences from people regarding the vaccine, the virus, and questions about both. Not studies, not numbers put out by news stations, but actual, real-life info.

Click to expand...

Oh dear. Please, I am begging you to rethink your position. Your "real life experiences" are anecdotes, nothing more. If you seriously rank them above serious studies, conducted by experts, then you are making a grave error. I use the word grave deliberately because following anecdotes, not studies is killing thousands of Americans. By speaking out in favour of them you are complicit in those deaths.

Apparently vaccinated people can still transmit Covid. That is why they are suggesting new mask mandates.

A CDC study of a COVID outbreak suggests vaccinated people may spread the Delta variant just as easily as unvaccinated.

The vaccinated cases in the Provincetown study (for which our lab did the viral sequencing) had scarily high viral loads -- at least as measured by nasal swabs. It may be that there's a lot of virus in the nose but not much in the lungs of vaccinated folks, which would explain why most had only mild symptoms.

Isaiah 41:10 said:

And I guess it would be fair to say that if individuals aren't infected, then they also would not then be able to pass the virus along, by extension. Is this correct?

Click to expand...

"Infection" needs definition. Does infection include touching a surface and carrying virus on one's fingers? Was that person "infected" and then as soon as he washed his hands no longer infected?

Or if a person who is fully vaccinated breathes in the virus and it resides for a short time without actually replicating before his antibodies slaughter it. Was he infected?

As a matter of practicality, I'd limited "infected" to persons in whom the virus is successfully replicating. I'd use a term like "contaminated" otherwise. Remember that each viral element has a limited span of time that it can remain active (I've not heard any information about this virus being able to go into hibernation in non-benign conditions). Unless it can find a living cell with the right receptors within a period of hours to days, it's going to become inactive and deteriorate. Even if it's entered a human body, it still has to find the right cells, or it will become inactive and deteriorate. And if that body already has defenses (from vaccination or prior disease), then there is also an active threat to the virus all along the way, so it will have only hours at best.

Viral dose counts. The fewer the absolute number of viral elements that have entered the body, the less likely any of them will find a receptive cell and the more likely the body's immunity defenses will overcome them before that happens. One hundred invaders are easier to counter than 1,000,000 invaders.

Immunity from prior disease is not as comprehensive as mRNA vaccine immunity because natural immunity is extremely specific to the characteristics of the virus it first encountered. It's like a soldier targeting only people in red uniforms who are also left-handed and red-headed, because the enemy they first encountered was left-handed and red-headed. The mRNA vaccine teaches the body to attack a more general characteristic, the spikes. That's like a soldier looking for everyone who fits a description with only one distinctive feature, like everyone in a red uniform, regardless of hair color and handedness.

All of this works down to managing the odds. Avoid breathing other people's exhalations to the greatest extent practicable, and also take measures to reduce susceptibility to an active infection--that is, to reduce or prevent replication in your own body by vaccines and other good health measures.

Push back the odds by any means practicable.