I’m just going to keep saying. And saying it. Because it is dangerous not to. The US is at herd immunity levels in many states. Everyone should therefore be MORE careful, wear masks, be a bit happy that the end is in sight but be really careful. Schools should NOT reopen at all, but especially in states like the Dakotas and Michigan and Western PA- you are about to see cases go up like wildfire.
Ok so here I present another analysis pointing towards herd immunity and address the two major criticisms of saying we have herd immunity 1. that the drop in cases is because states are being more careful and 2. that masks do work (spoiler- they do work but that can be included in the model).
First- the states that have the most total infections are now all decreasing while states with less infections are increasing. This means that they are going in the opposite direction you would expect if no herd immunity was happening. See below:
What’s green in the right map (decreasing daily new cases) is most red in the left map (highest percent of state infected). Also note, those green states are a lot of the states that were most vehemently opposed to masks and lockdown- places like Florida and Louisiana.
I more formally address this below. States with decreasing cases have on average ~6.5% more total infections than states that are increasing. The p-value from a simple two group t-test is p=0.0003. P-values<0.05 are significant- making this highly statistically significant.
Ok, so some people on the internet are saying- maybe that’s because Florida and Alabama and Louisiana and Texas are being more careful right now. First of all, does that sound right to you? With schools opening? In case that’s not convincing, here are some data present by Dr. Trevor Bedford at UCSF hospital grand rounds. This graph appears at minute 44 of that presentation. On the left is Open Table data (people going to restaurants) and Google Retail Mobility (shopping) trends. You can see that with reopening in Early May, Arizona and Florida have 60% more restaurant reservations and 30% more shopping. New York starts reopening in June and the restaurant and shopping trends also go up albeit with a delay from AZ and FL. Then AZ and FL sky rocket in cases but New York remains at exactly the same flat level.
I think this pretty adequately says two things: 1. AZ and FL were not super careful at least in mobility upon reopening and 2. New York has almost gotten to be as mobile as AZ and FL and yet did not spike. Together I can think of no other reason than herd immunity for this.
This does NOT mean that masks and distancing are not helpful- they are! Here is the another slide from Dr. Bedford, showing that RT depends on societal behavior. So as people wear more masks, don’t open schools, and distance the level to reach herd immunity drops- the effective RT.
This means the interventions, such as no school and wearing masks, do help! And should continue to happen in this critical time. Please be safe but also be smart and don’t believe the #fakesciencenews.