First preliminary data on vaccine efficacy against Omicron is here.
There is some immune escape, but it's partial and not complete. This is good news.
Science really does move fast. Not even two weeks after identification of the Omicron variant, we already have preliminary data on how well the vaccines work against Omicron.
We have early data from the lab of Dr. Alex Sigal in South Africa:
The experiment
In order to make sense of any data, it’s important to understand how the experiment was conducted. Here’s the paper if anyone’s interested. The lab used live SARS-CoV-2 viruses, both the ancestral (original) strain, and B.1.1.529 (Omicron), and infected a human lung cell line (H1299) with them. In a clever twist, they used H1299 cells that were engineered to over-express the ACE2 receptor, which is the “gate” that SARS-CoV-2 uses to enter our cells. Over-expression just means these cells were engineered to make (“express”) a lot of the receptor. They also tested H1299 cells that were not engineered to over-express this receptor.
To look at how well the vaccines work, they then took plasma from people vaccinated with the Pfizer/BioNTech vaccine, and assessed how well it would neutralize Omicron vs the original strain. They had 14 samples in total, and 6 of them had been infected with COVID prior (the original strain). So basically, about half were vaccinated with no prior infection, and the other half had prior infection AND were vaccinated.
Here’s what they found:
The ACE2 receptor is required for Omicron to enter the cells. This is good news as it indicates that Omicron hasn’t found another entry way into our cells.
There was a ~40-fold reduction in neutralizing ability against Omicron compared to the original ancestral strain. This DOES NOT MEAN the vaccine is 40 times less effective. This is just looking at neutralizing antibody levels.
Reduction was less pronounced in infected+vaccinated (hybrid immunity), compared to those never infected but vaccinated.
While there is some immune escape (as expected), this is partial and not complete.
Here’s a pictorial representation, taken from the paper by Dr. Sigal’s group:
So what does this all mean?
Well, first, there is a clear reduction in the neutralizing ability of the vaccine against Omicron, compared to the ancestral strain. This was expected, and a lot of variants have shown this as well, especially Beta. This means the virus is to some extent evade the vaccine. However, this is NOT complete, as there is still some degree of neutralization.
What this indicates is that boosters can help us combat this - remember, boosters significantly increase antibody levels and propel protection against infection right back to very high levels (~90%). Given the fact that the immune escape is partial and not complete, having more neutralizing antibodies (booster) can help us fight it off.
Third, the neutralizing ability of sera from individuals that had hybrid immunity (infection + vaccine) was hit LESS than sera from vaccine-only (no prior infection). The green lines being above the orange lines in the picture above demonstrate this. This adds to evidence we already have that hybrid immunity (infection + vaccine) provides robust immunity. So, if you’ve had COVID-19 already, it pays to get vaccinated to get that extra boost to protect yourself.
VERY IMPORTANT caveats
This is good but PRELIMINARY data, and subject to change. Also, this is looking at JUST neutralizing antibodies, in a test tube model. It is still unclear how this translates into in vivo (aka real life human beings). Remember, our immune system is much more complex and sophisticated than just antibodies - you also have the extremely important T-cell immunity, which is not tested in this study. T-cell immunity helps explain why vaccinated people are much less susceptible to severe disease, and I expect it to be the case for Omicron too.
That being said, this is still very important data and informs our knowledge.
What’s the bottom line here? Get vaccinated AND boosted. Don’t play the Russian roulette game of waiting for COVID to get you. If you’ve already been infected and are mulling vaccination, GO GET VACCINATED. Prior infection is no guarantee of protection from reinfection, especially as we continue to hear reports that Omicron may be causing more reinfections. Hybrid immunity (infection + vaccine) is probably the most robust protection you can get.
That’s all for now folks, hope this was helpful! I’ll keep posting updates as they come out.
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