Why is the 2nd wave leveling off?

Optimistically, 45 million+ people in the US have already been infected and are no longer in the pool of possible infections. Given there have been approximately 4.5 million confirmed cases and the CDC estimates this undercounts true infections by a factor of 10, this would mean ~14% of the US has at least some amount of immunity going forward.

https://www.bloomberg.com/news/articles/2020-07-21/coronavirus-infections-far-exceed-reported-cases-cdc-estimates

The first wave in Illinois is resurgent, and growing. I can’t understand why people think the sacrifices of the past 4 months should be thrown away. Deaths are down, levelling off and holding steady. Not dropping. But new cases in Illinois are on the up. When this first wave has been controlled, and people have gotten the chance to catch their breath, then talk to me about a second wave.

Yes, the change in reporting rules exactly corresponds to a fairly dramatic change in the slope of daily cases. I know there are other reporting channels and I haven’t done any kind of correlation analysis, but Florida and Texas turned right around after the 15th.

There were some early studies suggesting that a significant proportion of the population may have cell-mediated immunity deriving from prior exposure to other coronaviruses. Even without this, there may be high variance in susceptibility to infection. And that implies a natural slowdown (decrease in R0) when a significant number have been infected (see @Trom above), since the more susceptible people are infected early. It’s even possible that we may be approaching herd immunity in places like New York.

There area a lot of unknowns here, and the U.S. will be the place where these questions are answered. We’re the world’s pioneer experiment on letting the disease get completely out of control and discovering the dynamics of the path to herd immunity. It’s hard to imagine any endpoint other than herd immunity now in the U.S., with or without a vaccine.

My working theory is that virus spread is effectively slowed when enough of the public does the bare minimum practice to limit public contact and avoid strange respiratory droplets.

ISTM that the virus should have buzz-sawed right through Tokyo, being a dense international city with heavy public transit use, but they barely had any outbreak of note. I can’t think of any reason Tokyo should be special, but I know the Japanese public has always been diligent about masking just for routine seasonal illness.

By contrast I can’t see why the virus ever would have stopped in Texas or Florida or other conservative-ideologue states. They’re nowhere near the 60-80% needed for herd immunity. All I can figure is things suddenly started getting bad and a handful of people got scared and started distancing and masking, and the curve has flattened as a result.

It’s not all business as usual in Texas. Remember, the state is conservative, but the cities are liberal, so mask compliance is not a political issue. The state has limited the power of cities to deal with this, but dense municipalities still have some power. Plus, it’s getting to the point that we all know someone who has died or been very sick. In Dallas, traffic is still very light, masks are the norm, and it’s clear that people are heavily modifying their lives in response to COVID.

Are there are any discernible differences between Tarrant and Collin counties and Dallas? Because it’s fairly hard to find such stark political, and to some extent demographic, differences in other directly neighboring places, I would think. Isn’t Collin County one of the reddest counties of its size in the entire nation?

I honestly don’t know, in terms of on the ground compliance. I don’t go north, often, especially now, so I don’t see much. Their county judge has been highly resistant to closures.

@MandaJo’s comments apply equally to Florida. We’ve gotten real serious in the D-leaning major metro areas. We still suffer from lots of yong people who think outdoors in a group is safe, but that’s not nearly as crazy as it was when our Trumpist governor opened everything.

RIght now you’d never know FL was a state full of retirees. You simply don’t see gray haired people out anywhere hardly at all. We’re all hiding indoors using delivery. Meanwhile the young-ish people are loving it; lots more room at the beach & restaurants and no ugly wrinkles spoiling the scenery.

That plus rampant fakery in the White House’s official “statistics” is more than enough to explain what’s you’re seeing.

I can attest to this in San Antonio. People largely wore masks and definitely wore masks when the mayor and county judge started challenging the governor. Unfortunately, with the reopening, people went to bars and restaurants like everything was fine and we ended up with a terrible outbreak. We slowly started to crawl back after the city mandated masks and even before bars were shut down. It’s going to be a long hard slog back to where we were at the beginning of May.

So why didn’t ALL or at least most of the states flatten out at that point. Illinois and Misery have been on a steady trend up the whole month.

Looks to me like once a state hits about 2% (20k/1m) infected the curve flattens and drops. The states that hit it last spring have stayed relatively low. States that had an initial surge but got nowhere near 2% are currently climbing again. Somewhere on this board is a link to a study stating 40-60% of the population tested have T-cells that respond to and may mitigate or minimize Covid infections. This could put natural herd immunity starting at close to 50% already. 2% times the undercounted X10 factor may be all that is needed to get Covid down to the seasonal flu numbers going forward. This could possibly explain why one person gets it and their spouse that has been with them throughout does not. Also this could explain why the elderly are much harder hit.

There’s a an autocorrect error there, I think you meant Ill-inois and Misery.

States that got hit first tended to be more densely populated. More densely populated states tend to vote Democratic. Democrats tended to lock down harder and ease up restrictions slower. Correlation is not causation. For a counter example, look at Louisiana. They got hit hard first along with the northeast, and they’re getting hit hard now, just like the Republican led states.

Louisiana didn’t get to a 2% infection rate until recently, probably mid July or so which is about when they plateaued for this wave.

I tried to leave the red/blue crap out of it but since you brought it up, Illinois is also a Democrat state which was hit early and dropped but it has been slowly trending upwards since mid June. It’s curve is similar to Michigan’s, another Dem state.

None of this is to say that a state has to hit 2% to “succeed” but it is a trend I noticed at this point. Many states have reduced infection rates long before then, just a matter of keeping cases down. And we need to see if this wave in states near 2% is the final major one.

I’d be interested in seeing Illinois statistics by county and date. Chicagoland is strongly Democratic, but many areas downstate are deep red (Trump received 84% of the vote in Wayne County, for example). They are much less populous counties downstate, but which counties are now driving the trend upwards?

By region of the state is here. In absolute numbers it is currently the northeast section of the state (Chicago and its suburbs/exurbs) for cases just because the population there is big. On a per capita basis the northeast region is the lowest for new cases, not quite flat but close. Biggest rise and value is southern, then central and north central neck and neck. You can toggle to look county by county if you like. Cook itself is virtually flat now. Wayne’s per capita case numbers are jumping up.

The ‘first wave - second wave’ language is ultimately not helpful in conveying the behaviour of the pandemic. Where it has been used historically it seems to refer to the situation where the virus has swept through and caused havoc through a population who were exposed and either survived or carked. The survivors gained sufficient immunity [=current buzz-phrase ‘herd immunity’] to not be immediately re-infected. However the virus mutated sufficiently [antigenic drift] in some part of its spread to overcome such immunity, leaving the entire population which had been through the pandemic susceptible to the new strain in a second wave [or more accurately a back-wash].

From the numbers, the US is still seeing the initial dispersal of the virus into all corners of the country. Arguably, modern communications and knowledge of how to minimise spread have slowed it down and we do not know if there is a worthwhile residual immunity that will come from exposure. I think its still possible that populations will continue to be reinfected by the same strain of the virus, let alone a different strain that develops elsewhere.

Hopefully I’m wrong about the solid immunity but reporting to date is ambivalent.

When people are actually spreading the virus like wildfire, that doesn’t make the news because there’s no data at that point. During this time, people continue to spread the virus even more until the first wave of reported cases comes in. Then the infection rates make news, but no serious illnesses or deaths initially. But after another 5-7 days, people start going into ICUs, the hospital beds fill up, the cameras start rolling, and then the body bags start piling up. This cycle takes about 21-28 days. Through a combination of government policies, business policies, and people just getting understandably concerned, the behaviors that spread the disease begin to change, and so the curve begins to level a little. But bear in mind, in many cases, by “flattening” we’re talking about a slowdown in the growth rate, not an actual decline.

Without doing a super-deep dive into the exact reporting chain for the numbers, and how they relate to hospitalizations and deaths (some of which can’t be done yet, as those are trailing indicators), as well as overall death rate from all causes for the state, it’s hard to say anything with any certainty. But there’s no reason to believe that individual states couldn’t maintain high standards of reporting, even as the national collection of the data falls off a cliff. I have no reason to believe to believe that Washington (state) has in any way changed its data reporting, for example. If I lived in Florida, I’d be a lot more concerned - and that’s even before testing was shut down due to the incoming hurricane.

I think the 10x estimate is outdated. While Trump’s theory that all of the increase in cases is caused by testing is clearly false, we are testing more, and the likely percentage of cases that are caught is almost certainly higher now than it was in March.

I now see there is a separate thread on this. It’s somewhat off the rails at the moment, but seems like the right place to continue this conversation, if anyone were so inclined.