Thread by @segal_eran

Israel: Signs of vaccines affecting national pandemic dynamics

Drop in cases & hospitalizations of 60+ y/o in cities vaccinated early

Stronger than in late-vaccinated cities

Stronger than in younger people (only recently eligible)

Not seen in previous lockdown

**Caveats**
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Joint work with @ShalitUri, @GorfineMalka, @H_Rossman

Situation in Israel today:

https://twitter.com/segal_eran/status/1355620710069248001?s=20

When trying to identify the effects of the vaccination we’re hampered by the fact that right as the vaccination drive started Israel went into its 3rd lockdown following an unprecedented rise in infections (possibly due to the B117 strain).
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Therefore we need to tease apart the effect of the lockdown from that of the vaccinations and the new strain.
Luckily, we have 2 natural sources of variation that we can use to tease apart vaccine effects:
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1 - Age: for the first few weeks of the drive, mostly ages 60+ were eligible to be vaccinated
2 - Variation across municipalities: some were quick to get vaccinated, some less so
(much of the variation in correlation with SES

https://twitter.com/MDCaspi/status/1352590064900038662?s=20

)
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Here is the rate of (1st dose) vaccination in all cities in Israel with more than 5k aged 60+ population

Early vaccinated cities: cities that have at least 85% of ages 60+ vaccinated by 10/1

Late vaccinated cities: cities that have not reached 70% of 60+ vaccinated by 10/1

Finally, in order to try and control for the effects of the lockdown, we compare with the dynamics of the 2nd lockdown which started in Sept. 2020.

We therefore make a triple comparison:
Ages 60+ vs. 40-60
In early vs. late vaccinating cities
In the 3rd vs. 2nd lockdowns

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For example, hospitalizations for aged 60+ in the early vaccinated cities (green) declined faster and steeper compared to late vaccinated cities (red) in the 3rd lockdown (middle row);
and very different to the behavior exhibited in the 2nd lockdown for these age groups (top row)

The 60+ age group also declines faster and steeper when compared to a younger age group (age 40-60), and this behaviour is also very different in the 3rd lockdown compared to the 2nd

Positive PCR tests exhibit an even sharper contrast, but these are from routine testing data in Israel, where vaccinated individuals post 2nd dose do not need to be tested in order to be exempt from isolation. Nonetheless, this provides a good sanity check

And severe hospitalizations

Next step forward would be to conduct a formal statistical analysis to quantify and solidify these findings, as days go by and vaccination effects should become stronger

Preprint coming soon