Oxford Vaccine, Explanation please.

[fireflylanegirls]

I read an article yesterday about a recent study carried out on the Oxford vaccine.

It said that the vaccine was 79% effective at stopping symptomatic Covid and 100% effective at preventing people from falling seriously ill

What exactly does this mean?
Does it mean that 8 out of 10 people (roughly) won’t get Covid, and the 2 that do will be 100% protected from severe illness?

Or, does it mean that 8 out of 10 people that get Covid will be 100% protected, and the other 2 aren’t protected?

Sorry if this is a stupid question, just not sure what it means.

I think it's your first suggestion - 8 out of 10 people won't develop symptoms of covid, and the 2 out of 10 who do develop covid will have 100% protection against serious illness.

But I agree, it is a bit ambiguous.

I take it to mean that 8 out of 10 who do still get Covid will not have any symptoms ( hence the symptomatic. Meaning 2 will still get some 'mild' symptoms.
And of everyone who has had the vaccination (those 2 with the symptoms) none will end up in such a poor state that they end up in hospital.

Not a stupid question, this stuff is complicated.

They are describing what happened to a group of people in the past, not predicting what will happen in the future.

In the study, 8 out of 10 vaccinated people were protected as compared to people who were not vaccinated. None of the vaccinated people were seriously ill.

@Spied

I take it to mean that 8 out of 10 who do still get Covid will not have any symptoms ( hence the symptomatic. Meaning 2 will still get some 'mild' symptoms. And of everyone who has had the vaccination (those 2 with the symptoms) none will end up in such a poor state that they end up in hospital.

@Spied

So overall it’s good results then!

@MrsAudreyShapiro

Not a stupid question, this stuff is complicated.

They are describing what happened to a group of people in the past, not predicting what will happen in the future.

In the study, 8 out of 10 vaccinated people were protected as compared to people who were not vaccinated. None of the vaccinated people were seriously ill.

@MrsAudreyShapiro

That’s that part that confused me.

If 8 out of 10 were protected, is it those 8 out 10 that had 100% protection?

Or do they fall into the 79% who develop no symptoms, and 10 and 10 are 100% protected from severe disease, with only 2 people developing any symptoms.

It means that for every ten vaccinated people that get symptomatic covid only two vaccinated people do and no vaccinated people get seriously ill. So everyone in the trial got enough protection from the vaccine that they didn't get very sick and most people got so much protection that they didn't get stuck at all.

*didn't get sick at all.

@QueenStromba

It means that for every ten vaccinated people that get symptomatic covid only two vaccinated people do and no vaccinated people get seriously ill.

Only two vaccinated people do what.? Get symptoms?

It's possible you are overthinking this, all your descriptions are saying the same thing, just in different ways.

79%: don't get covid, they don't have symptoms and are protected - these all mean the same thing. Remember Covid is the name for the illness caused by coronavirus.

21% will have mild symptoms, so some form of protection/benefit, not full protection, but enough to remain well.

[quote fireflylanegirls]@QueenStromba

It means that for every ten vaccinated people that get symptomatic covid only two vaccinated people do and no vaccinated people get seriously ill.

Only two vaccinated people do what.? Get symptoms?[/quote]
Yes, get symptoms.

Its pretty much what you have said.

79% of vaccinated people will not develop symptoms of covid (they might still get infected and this could show up if they are being regularly tested but they will not develop any symptoms at all)

Of the remaining 21% that do develop covid symptoms none of them will become seriously ill with it.

@QueenStromba has this right.

It is all evidence from the trials, comparing the vaccinated group to an unvaccinated control group.

Let’s say there was 1000 people in each group. In the unvaccinated group 50 people caught covid and 5 were seriously ill. In the vaccinated group 10 caught symptomatic covid and 0 were seriously ill.

That would be evidence for the effectiveness levels described above.

@Comefromaway

Its pretty much what you have said.

79% of vaccinated people will not develop symptoms of covid (they might still get infected and this could show up if they are being regularly tested but they will not develop any symptoms at all)

Of the remaining 21% that do develop covid symptoms none of them will become seriously ill with it.

Kinda. It’s not predicting how many vaccinated people will get covid in the future.

It’s saying, all other factors being equal, a vaccinated person is 79% less likely to get symptomatic covid compared to an unvaccinated person, and 100% less likely to be seriously ill.

The actual chance of either person actually getting covid will depend on how much the virus is in circulation.

In a group of 100 people who received the AZ vaccine, 80 will be completely protected. 20 of them IF they come into contact with the virus, might catch Covid (and remember, not everyone who comes into contact with it, gets it) but it will only be a mild to moderate case, and they won't die or be hospitalised.

Getting the vaccination doesn't mean you have a 20% chance of getting Covid. Because there's going to be a lot less of it around to come into contact with, and even then your contact might not lead to anything (I know 2 people from different families who had it, live in small houses where they couldn't stay away from their family, yet no-one else tested positive in their household.

Don't forget there are other risk factors like age and other health conditions. That's part of why it's complicated.

But I'd say that 100% protection from serious illness or death is an excellent result.

Just throwing this out there.....

If 79% of vaccinated people don’t have symptoms won’t that increase the risk for the non vaccinated? Because a vaccinated person could be walking around with covid and not realise, whereas before they’d have stayed at home?

@CovidCorvid

Just throwing this out there.....

If 79% of vaccinated people don’t have symptoms won’t that increase the risk for the non vaccinated? Because a vaccinated person could be walking around with covid and not realise, whereas before they’d have stayed at home?

The 79% who don't get symptoms includes people who never have a high enough viral load to test positive i.e. the immune system eliminates the virus before it has a chance to take hold. True asymptomatic transmission is actually fairly rare - most people who pass it on while asymptomatic go on to develop symptoms later. The main reason we do asymptomatic testing and isolation is that we don't know who will remain asymptomatic and who will do on to develop symptoms later. Also, previous data from the Oxford trials shows a significant reduction in positive PCR tests in vaccinated people so it does actually prevent infection rather than just prevent symptoms.

Thank you, that makes sense.

I think this is an excellent question and am glad you started the thread op.

@CovidCorvid

Just throwing this out there.....

If 79% of vaccinated people don’t have symptoms won’t that increase the risk for the non vaccinated? Because a vaccinated person could be walking around with covid and not realise, whereas before they’d have stayed at home?

Most people who are infected with covid walk around for many days without realising it. It's got an average of 4-5 days incubation - a lot of those infected have it for a week before symptoms show! But it takes 2-3 days to build up in the system so you're not immediately infectious.

With a vaccine, it's a question of how quickly they eradicate the virus from their system, but the chances are that if they don't show symptoms, it's been wiped out within the first 3 days - that puts you borderline on whether or not you'd test +ve for infection, but makes it highly likely you won't be able to infect others.

Where the vaccine doesn't stop symptoms, but does stop serious illness, then yes - these people would likely be infectious the same as if they hadn't been vaccinated as the immune response has clearly taken longer to occur.