Before I begin, I have to clarify that I’m only looking at the effectiveness of vaccines against the original Omicron variant in this post. I have no information about the Omicron BA.2 variant.
First up, a truth that no government wants to admit: neither Pfizer, Moderna or AstraZeneca do much to protect against symptomatic disease with Omicron:
I took this data from a study that appeared in the New England Journal of Medicine: https://www.nejm.org/doi/10.1056/NEJMoa2119451 If you scroll down to Table 3, which appears just before the Discussion, you can check the raw data for yourselves. This data compares the effectiveness of all three vaccines against the Delta variant and the Omicron variant. This is an example:
As you can see, AstraZeneca is shown by its scientific name rather than the one we’re all familiar with. The same applies to Pfizer – BNT162b2 – and Moderna – mRNA-1273. For each vaccine, Table 3 displays its effectiveness against Delta and Omicron at specific time points. The 2 – 4 week time point is when the vaccine is at its most effective in preventing symptomatic disease. You can then see how quickly that effectiveness wanes over time.
Because I found the presentation of the data a bit hard to follow, I translated it into a spreadsheet and made it more visually clear:
Despite my best efforts, the data is still confusing so let me walk you through it. On the far left you have the effectiveness of the three vaccines at just 2 doses. As you can see, after 5 months, none of them are very effective and AstraZeneca is the least effective of all. This means that if you are Australian, over 65 and received only 2 doses of the AstraZeneca vaccine, you have virtually no protection. AT. ALL.
Until just 2 weeks ago, I fell into the ‘no protection at all’ category.
Now let’s have a look at what effect the boosters have. I’m going to start by looking at each vaccine boosted by itself – i.e. by a third dose of the same vaccine.
Looking at the table above you can see that 2 doses of AstraZeneca boosted with a 3rd dose of AstraZeneca – i.e. 3 doses of AstraZeneca – provides a maximum of 55.6% protection at 2-4 weeks. By week 9 – just over 2 months later – that protection has dropped to 46.7%.
Two initial doses of Pfizer followed by a Pfizer booster – i.e. 3 doses of Pfizer – provides a maximum of 67.2% protection. By week 10 that’s dropped to 45.7% protection.
Two initial doses of Moderna followed by a Moderna booster – i.e. 3 doses of Moderna – provides a maximum of 66.3% protection. I can’t tell you what that protection becomes at week 10 because there is no data for it. The reason there’s no data is because there were only 7 people in the study who had 3 doses of Moderna. I guess that was simply too small a sample size to be significant.
To recap, 3 doses of the same vaccine at weeks 2 – 4 – i.e. when protection was highest – resulted in:
- 55.6% protection for AstraZeneca
- 66.3% protection for Moderna
- 67.2% protection for Pfizer
Pfizer comes out on top, but only by a very small percent. AstraZeneca is roughly 11% worse than either of the mRNA vaccines. That said, the level of protection still isn’t stellar…for any of them.
Now, let’s see what happens when you mix-and-match vaccines.
When AstraZeneca is boosted by Pfizer, the level of protection at week 2-4 is 62.4%. AstraZeneca boosted by Moderna provides quite a bit more protection at 70.1%.
Significantly, boosting with Moderna causes that protection to also wane less by weeks 9 – 10:
- 60.9% with Moderna
- 39.6% with Pfizer
I’m pleased to say that I received my Moderna booster two weeks ago so my protection is reasonably high. I say ‘reasonably’ because I only have 1/2 a thyroid. That means my immune system is a bit compromised and the vaccines can’t provide me with the same level of protection.
The most interesting bit of data, however, is yet to come.
If you received two doses of Pfizer and followed that up with the Moderna booster, you will have the highest level of protection at 73.9%. By contrast, two doses of Moderna followed by a Pfizer booster will only give you a 64.9% level of protection.
So in conclusion:
- Get a booster as soon as you hit the 3 month mark [after your second dose of whatever].
- If at all possible, get the Moderna booster, especially if you received AstraZeneca as your base vaccine.
- Any booster is better than none.
- Keep taking precautions even after you receive your booster – even 73.9% protection isn’t all that much.
The study I’ve referenced here only looked at protections from symptomatic disease. Not severe disease. Not death. If the vaccines work the same way against Omicron as they did against earlier variants then there’s a good chance they will protect against severe disease and death, but the data isn’t in yet, so they may not. And given that BA.2 is a bit of an unknown quantity, we don’t even know if the boosters are as effective against it as they are against BA.1.
Governments and media have gone quiet on the pandemic, leading a lot of people to believe that the danger is over. It’s not. It’s just that no-one wants to admit that vaccines are not the magic bullet we were promised. The continuing death toll here in Australia and elsewhere in the world is proof of that.
Get your booster. Wear a mask. Don’t be a fool, the life you save may be your own.