The coronavirus outbreak tied to the annual motorcycle rally in Sturgis, South Dakota, ended up generating more than $12 billion in public health costs, according to a new discussion paper.

Why it matters: The analysis puts a point on just how bad these superspreader events can be — and the difficulty of preventing them solely with voluntary policies.

Background: The annual rally was held this year over 10 days in August, and included a Smash Mouth concert. The nearly 500,000 attendees came from all over the country, and social distancing and mask-wearing were mostly optional.

By the numbers: The rally led to 266,796 additional cases, or 19% of the new cases in the U.S. between Aug. 2 and Sept. 2., the paper found.

• The event led to a 35% increase in cases in South Dakota. In counties that are home to the highest number of rally attendees, cases rose by 10.7% compared to counties without any attendees.
• If each coronavirus case costs $46,000, that's an additional $12.2 billion added on to the pandemic's price tag.

The other side: "Overall, I think the 'Sturgis Effect' that the authors document is in large part just a Midwest surge that took place during this time period. There is likely still a small Sturgis Effect ... but the results are likely biased upward," tweeted Devin Pope, a professor at the University of Chicago.

The big picture: Given the state of contact tracing in the U.S. (bad), we'll never know how many coronavirus cases were actually tied to the Sturgis rally.

• But it's a reminder that it takes collective action to contain the virus: As Sturgis revelers head back home, this South Dakota-centered outbreak has the potential to infect people who never went anywhere near Sturgis and thought they were doing everything right.

AstraZeneca's Phase 3 clinical trial of a coronavirus vaccine has been put on hold following a suspected serious adverse reaction in a participant, STAT reports.

Why it matters: This is bad news for those of us who want a vaccine, although there are several others in advanced stages of the development pipeline.

• But the fact that we know about the suspected reaction is a good sign amid concerns about politicization of the approval process.
• AstraZeneca initiated the hold on the trial. Details about the reaction are unknown, but the participant is expected to recover, per STAT.

What they're saying: A spokesperson for the company said that the pause is "a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials."

Details: The U.S. trial is taking place at 62 sites across the country, and other trials are underway in U.K., Brazil and South Africa. The participant with the adverse reaction is in the U.K.

It's hard to find coronavirus tests for kids, which is not good in light of school- and day care-related spread, the New York Times reports.

Why it matters: Just like adults, kids are expected to stay home when they have coronavirus symptoms or when they've been exposed to the virus. If they can't get a test, that often puts parents in the position of staying home with their children for two weeks.

• The lack of tests can also tie schools' hands as they attempt to trace and isolate the contacts of coronavirus cases.

Between the lines: Many testing sites have age requirements for tests, even in large cities with lots of sites. The age limits vary widely.

• "The age policies at testing sites reflect a range of concerns, including differences in health insurance, medical privacy rules, holes in test approval, and fears of squirmy or shrieking children," NYT writes.

Progress in treating heart disease, cancer and stroke were helping to drive the improvement in Americans' life expectancy before the opioid crisis sent it tumbling, according to a new study in Health Affairs.

By the numbers: From 1990 to 2015, Americans' average life expectancy rose by 3.3 years, Axios' Marisa Fernandez writes. The study attributes 1.76 years of that improvement to reduced mortality from heart disease, 0.34 years from lung cancer and 0.33 years to improved care for stroke.

Between the lines: This is what's supposed to happen — advancements in care and better public-health awareness are supposed to help life expectancy tick up every year.

• In the years just after this study cuts off, though — beginning in 2015 — American life expectancy declined for four years in a row, for the first time in decades, because of the opioid epidemic.
• It began to rebound again in 2018, according to CDC data.

Mark Zuckerberg told "Axios on HBO" that he's not ready to move against anti-vaxxers the way he did against COVID misinformation: "If someone is pointing out a case where a vaccine caused harm or that they're worried about it — you know, that's a difficult thing to say from my perspective that you shouldn't be allowed to express at all."

Our thought bubble, via Axios' Sam Baker: Misinformation about vaccines has spread rampantly on tech platforms for years, and has been linked to outbreaks of once-vanquished diseases like measles.

• And though Zuckerberg said Facebook will work with health authorities to try to provide reputable information about the COVID vaccine, this is likely to be a perfect storm of confusion, politically motivated reasoning and straight-up misinformation.

Go deeper.

The Biden campaign called on President Trump on Tuesday to answer three specific questions before releasing a coronavirus vaccine, while simultaneously warning that Trump may seek to short-circuit the scientific process for the sake of his re-election.

Group gatherings larger than six people will be banned in England as the country struggles with a rising number of coronavirus cases, the BBC reports.

House Speaker Nancy Pelosi (D-Calif.) and Senate Minority Leader Chuck Schumer (D-N.Y) denounced Senate Republicans' plan to introduce a pared-down coronavirus stimulus bill on Tuesday, saying the "emaciated" bill "is headed nowhere."

An estimated 62% of American schoolkids are starting the year virtually, with many of the rest facing the same fate should caseloads rise in their areas. Only 19% have in-person school every day, with another 18% in hybrid formats, according to a Burbio tracker.