Proof that vaccination has worked extraordinarily well against a Coronavirus delta variant during an epidemic.

There is much to learn from the COVID-19 outbreak in New South Wales these last months because almost all infections are detected and we can assume little previous disease exposure in anyone exposed to infection. The immunity status of everyone exposed is being carefully monitored.

It's a natural experiment on a grand scale.

The New South Wales state health agency provides valuable reports on these events.

Here is an image from a recent report from that agency:

The graph on the left panel above shows the great difference in infection rates between fully vaccinated people as compared to unvaccinated people during the course of this June-November 2021 outbreak. It shows unvaccinated people getting more than 10 times the number of infections suffered by the fully vaccinated.

A similar pattern is seen if you track severe disease outcomes -- ICU entry and death-- shown on the left panel of the graphic above.

It's helpful to look carefully at disease outcomes at the peak of the outbreak (late August-early September). These are displayed in the following panel:

Infection rates among the unvaccinated dwarf those in the vaccinated community. 

Extremely severe illness -- represented by ICU entry and death -- is about 16-fold more frequent among the unvaccinated than the vaccinated.

Vaccination works against Delta variant that's causing the NSW outbreak.

These clear patterns demonstrate the validity of  two important infection control concepts.

• Full vaccination can provide robust protection against infection by the SARS-CoV2 delta variant in an epidemic situation.
• Full vaccination protects most people against needing intensive hospital care (ICU) and from death.

Vaccines do the tough tasks extraordinarily well.

Thanks yet again, New South Wales public health and medical workers.