Vaccinating Football Players

the first.

 

They simply don't know yet whether any of the vaccines do a good job of preventing transmission or are mainly just symptom reducers.
https://www.fredhutch.org/en/news/center-news/2020/12/covid-19-vaccines-transmission.html

 

https://www.nhs.uk/conditions/vaccinations/flu-influenza-vaccine/

The same will be true of the Covid vaccines. You might still get it, but it will likely be a milder illness. By not being as sick you will be less likely to spread it.

By ensuring patrons have had a vaccine, venues will help prevent the transmission of Covid to those who may be too ill to have the vaccine.

 

“Disease” is the illness a virus causes. It is the SARS-CoV-2 coronavirus that infects cells which causes the COVID-19 disease. The ability to prevent disease (not infection) is a vaccine’s efficacy.

Just as an aside, its difficult to compare efficacy of different vaccines as it depends where you set the bar for preventing disease (mild symptoms vs severe symptoms). For example, the Astra Zeneca vaccine has a lower reported efficacy than the Pfizer vaccine, but in the AZ trials no patients were hospitalised.

The vaccine trials were not designed to measure the impact of the vaccine on transmissibility, only their ability to prevent disease. So when the scientists say there’s no evidence to suggest it prevents transmission, that’s not the same as saying it doesn’t prevent transmission. Indeed, the expectation is that it will prevent transmission to a degree, we just don’t know how much yet. Therefore if you’ve been vaccinated you still have to be careful until we understand more.

I admit I’m no expert, but my understanding is that transmissibility depends on a person’s viral load, which is the amount of virus they have in their body. A virus works by attaching to and entering cells. It replicates inside cells and creates more versions of the virus which go onto infect more cells. It is the accumulation of infected cells that eventually causes the COVID-19 disease.

The new variant of SARS-CoV-2 is more transmissible as it is more “sticky” (more likely to attach to cells) and can more easily enter cells (i.e. “unlock” them). Therefore, people who catch the new variant have a higher viral load, and therefore when they breathe/cough the air droplets contain more of the virus.

Vaccines generally work by priming the immune system so it already has antibodies that can attach to and neutralise infected cells. This prevents them from creating copies of the virus so they can’t infect other cells. The fewer infected cells, the less viral replication, the lower the viral load and the lower the transmissibility (as well as the reduced likelihood of severe disease).

However, whilst the antibodies will prevent too many cells becoming infected with the virus to cause severe disease, there will be a period of time where the person still has some viral load, before the antibodies have had chance to neutralise all/enough of the infected cells. It is during this initial period that you could still pass on the virus, even if the vaccine means you have sufficient antibodies to prevent severe disease. The question is how quickly will the immune response activated by the vaccine reduce viral load.

My separate concern is that although the scientists say there is no evidence to show the new variant of the virus causes more severe disease, that is just because the evidence isn’t there to prove the hypothesis yet. You would expect that a virus which can infect cells more easily to cause more severe disease. The second wave could be far more deadly than the first unless we get the vaccine rolled out as quickly as possible.

 

A vaccine / immunity can’t stop the virus particles entering your system.

If you have immunity, the virus will not get a foothold, and will not be able to reproduce effectively - and it will also have difficulty spreading to others. Eventually it will be eradicated from your system.

Depending upon the effectiveness of the vaccine, the above is going to be a sliding scale.

More often than not, the symptoms are the result of the battle between your immune system and the virus. Therefore, you can be infectious in the period when you have no symptoms because the virus is freely reproducing and your immune system has not yet got up to speed.

 

That's not correct. It's worth you reading up about this. There are no vaccines that, for the people they protect, leave them susceptible to the disease, allowing milder symptoms, and leaving you liable to infect others. If that was the case, it would have a efficacy of zero and would not be considered a vaccine.

There are few, if any, vaccines that protect everyone. Most vaccines have a very high efficacy and protect a very high percentage of the population. However, for a few people, a couple of percent or so, a vaccine doesn't produce the expected immune response. More often than not, in such cases, it results in something exactly as you've described. A much milder case and with the potential to pass on the disease. A sliding scale as you put it, which is a good description. It's not that the vaccine didn't work at all, it's just that it didn't have the optimum effect, so there is this battle between a weakened but still active immune response and the virus. But such people are not considered to be immune to the virus. They are in the percentile for whom the vaccine did not work.They are the ones who reduce the efficacy from 100%.

There's also the possibility that a vaccine has a shelf life in your system, and it won't continue to offer immunity after a certain period of time. However...

For those for whom it does wok, this isn't the case at the point of immunity. The immune response hits the virus at source, before it enters cells and is allowed to reproduce. If the virus does manage this, the cells are killed outright, before the virus can be expelled and infect others. You're not infected and you don't pass it on. That's what immunity is. What you and blivy have written is just wrong. I'm sorry, but it is.

If the vaccine we've administered doesn't do this, it's not a vaccine. But I suspect that isn't the case, it does give immunity, and there has been a misunderstanding. And we all better hope so.

 

Things like this don't endear them to the public:

 

Hi Jay. I’m sure we are saying the same thing here.

If no-one gets COVID-19, the efficacy is 100%.

If two people get it (out of 100), it’s 98%.

I think the efficacy of the COVID-19 jab (single dose) is about 60%. Not great. Two doses is much higher.

However, the hope is that one dose provides a sufficient level of immunity to keep people out of hospital (or worse). I think I have heard people using the efficacy figure as “60% less ill” than they would have been. I don’t think that’s correct, since how can they possibly measure this?

 

Hi mate. I think we probably are and it's definitely not worth arguing about (particularly as I'm at the very edge of my understanding on the subject). I have a tendency to be a bit intense, I'm aware of it, and I try to reign it in, but sometimes (often) it gets out. FWIW I read your post (and that of blivy) a number of times, I absorbed it, then read a lot of articles on the internet, not in an attempt to prove you wrong but to further my knowledge, and then attempted to give a response that I hoped would be worthy of the thought you'd put in to your reply to me. Thank you for your subsequent friendly post and for giving me something to think about on this cold January weekend.

 

Not at all. I usually feel bad if I give a short reply in response to a long one!

BTW, I realised afterwards my over simplified explanation of efficacy, because you have to take into account the placebo group. Even without the vaccine not everyone gets the disease.

IIRC Pfizer are unhappy with the single dose approach because it does not provide the intended level of immunity - which is at the heart of your original point. They never did a single dose trial, and the vaccine was not approved for use in that way.

 

I suppose they will be upset when they are unable to fulfill their 4th rnd match.

 

Clubs can be sold them for £3 each or two for a Pfizer.