SvennoJ said:
Israel was the first to vaccinate en masse. Perhaps the immune response goes down faster over time than previously assumed. Still plenty to fight off serious disease, but not enough prevent some illness. Here they are already talking about the need for booster shots for the most vulnerable groups. |
I've found some comments on this from Israeli professors looking at the subject. It looks like waning might not be as fast as some were prematurely claiming, and is perhaps as slow as those estimates for natural immunity from the UK:
"Are we seeing immunity waning in Israel? The MoH shared some raw data, and together with @geller_mic we tried to get a qualitative answer to this question. TL;DR – it seems that there is immunity waning, increasing risk of infection of early vaccinated by ~80%. ==>
The problem is that it's not clear what proportion of the population was vaccinated early. 770K is 18%, but this is problematic. It includes non-vaccinated, ultra-orthodox and Arab citizens (the current wave has not spread to those groups yet).
We looked at how many were vaccinated in “general” pop cities, and we estimate it at about 22%. If this is the background that we need to compare to, it means that early vaccinated are at ~75% higher risk for infection. If VE is ~90%, after half a year it drops to ~82.5%.
Now to adults. Here we have 370 cases in early vaccinated from 421 total (88%). What is the expected rate? We estimate it at about 79% of 60+ in the general population. This translates to about a factor of 2 in risk, or if VE is 90% then after half a year later it drops to 80%.
Delta might affect VE, but it's very hard to estimate it based on Israeli data. The data suggest that non-vaccinated adult individuals are reluctant to get tested, which skews calculations towards very low levels of VE.
I personally think that Delta VE is still around 90% for infection, but we will have to wait for better studies. Our analysis does show that after half a year or so this 90% drops to around 82%. It’s a significant reduction, but not a game-changer.
Note that we are comparing here vaccinated individuals to vaccinated individuals. It still might be that “late” vaccinated individuals tend to get tested at lower rates or other biases we can’t assess here.
What can explain this trend except waning? Maybe early vaxxed are more aware of COVID-19 and get tested at higher rates. This can be tested by the MoH."
