Live data from Hacker News

Omicron largely evades immunity from past infection or two vaccine doses

imperial.ac.uk

21–30 of 161 posts

Re: Omicron largely evades immunity from past infection or two vaccine doses

#21

Does anyone understand why a third dose of the same vaccine improves immunity to Omicron? I'm willing to believe the empirical evidence that boosters make a meaningful difference, but I can't figure out intuitively why the same mRNA a third time helps to address this new spike.

In other industries they call this "sales": getting rid of current perishable stock before buying fresh one. It's there, we might as well use it.

Re: Omicron largely evades immunity from past infection or two vaccine doses

#22
post #4

If it evades immunity from past infection isn’t it a different virus in the practical sense?

Well, since the booster seems to protect, no? I am hoping that Omicron will boost immunity versus delta while being more mild. This makes me suspect that this will be the case: https://abcnews.go.com/Health/wireStory/omicron-dominant-was... "Even though there have been practically no cases of clinical infection, wastewater samples show that the new omicron variant is now the dominant strain of COVID-19 in the Florida…

> Well, since the booster seems to protect, no?

That hasn't been proven, as far as I know. Pfizer did some in vitro study but we still have no idea if that translates to real world results.

Re: Omicron largely evades immunity from past infection or two vaccine doses

#23

Does anyone understand why a third dose of the same vaccine improves immunity to Omicron? I'm willing to believe the empirical evidence that boosters make a meaningful difference, but I can't figure out intuitively why the same mRNA a third time helps to address this new spike.

One of the theories is that the booster raises the levels of neutralizing antibodies. While the antibodies against the original strain don't work as well against Omicron, having more of them does help.

Re: Omicron largely evades immunity from past infection or two vaccine doses

#24

Does anyone understand why a third dose of the same vaccine improves immunity to Omicron? I'm willing to believe the empirical evidence that boosters make a meaningful difference, but I can't figure out intuitively why the same mRNA a third time helps to address this new spike.

Mutations in spike proteins don’t completely change it’s shape so they render a percentage of antibodies infective vs that specific strain. A boosted immune response can therefore be less efficient but still useful.

To simplify, Vaccines provide long term protection because the immune system builds infrastructure to rapidly create antibodies after infection cutting days off of the immune response. That’s huge because the virus has less time to replicate in your body. Vaccines use multiple injections to increase how much infrastructure is built and the number of types of antibodies being produced. Also this infrastructure decays over time if you never see the strain again.

However, in the short term your body reacts like it’s infected actually flooding the body with the appropriate antibodies. This isn’t sustainable but can crush most infections before they go anywhere. Kind of a bonus turbo mode which can be really helpful if your say going to treat people infected with the disease.

Re: Omicron largely evades immunity from past infection or two vaccine doses

#25

Does anyone understand why a third dose of the same vaccine improves immunity to Omicron? I'm willing to believe the empirical evidence that boosters make a meaningful difference, but I can't figure out intuitively why the same mRNA a third time helps to address this new spike.

Because of the way your immune system works. Vaccines aren't medicine, they work by provoking an immune response. What happens after that immune response is triggered is way more complicated than just "molecule X get response Y", there are multiple stages of responses, and the deeper, longer span ones create a resilience against mutations as well.

It is extremely common for a proper vaccination regimen to require multiple doses, and it has entirely to do with how the immune system works.

Re: Omicron largely evades immunity from past infection or two vaccine doses

#26

Does anyone understand why a third dose of the same vaccine improves immunity to Omicron? I'm willing to believe the empirical evidence that boosters make a meaningful difference, but I can't figure out intuitively why the same mRNA a third time helps to address this new spike.

[deleted]

Re: Omicron largely evades immunity from past infection or two vaccine doses

#27

Realistically we are probably going to be exposed to Omicron in the next 3 weeks here in the UK, is there much point in having a booster right now? Are we sure that it will actually be providing protection if I got a booster today and got COVID in, say, the next 7 days?

I’m sure if you got COVID a few days after you’d be protected you’d be kicking yourself. I got mine yesterday after booking on Monday so you might be able to get it sooner than you think. I didn’t even take the first day available due to a conflict.

Re: Omicron largely evades immunity from past infection or two vaccine doses

#29
It's worth clarifying: un-boosted vaccination or past infection seem to have greatly reduced ability to prevent infection with Omicron. There is still substantial (lessened, but not as drastically lessened) protection against serious illness / death.

My understanding is that protection-against-infection and protection-against-death rely on different aspects of the immune system. The primary protection against initial infection comes from antibodies, which are narrowly targeted. Other systems are more flexible, but don't kick in quickly enough to ward off a mild infection.

And the takeaway is still: get vaccinated, get boosted.

Re: Omicron largely evades immunity from past infection or two vaccine doses

#30
post #22

Earlier quoted context omitted.

Well, since the booster seems to protect, no? I am hoping that Omicron will boost immunity versus delta while being more mild. This makes me suspect that this will be the case: https://abcnews.go.com/Health/wireStory/omicron-dominant-was... "Even though there have been practically no cases of clinical infection, wastewater samples show that the new omicron variant is now the dominant strain of COVID-19 in the Florida…

> Well, since the booster seems to protect, no? That hasn't been proven, as far as I know. Pfizer did some in vitro study but we still have no idea if that translates to real world results.

That is an accurate statement I believe. However, given it is the only available evidence we have, it is probably the most accurate prediction that we have, so let's call it our prior.
Post reply on HN