What the 1918 flu pandemic shows us about social distancing

Gov. Gretchen Whitmer’s stay-at-home orders prompted conservatives to organize protests, but Whitmer said she will base decisions on how and when to relax Michigan’s social distancing guidelines on facts and science.

At a press conference April 15, Whitmer said that the protests where people gathered without masks in close proximity "may have just created a need to lengthen it, which is something that we’re trying to avoid at all costs."

Whitmer said she is working with experts in health care and other sectors to create a data-driven approach to reopening the state. "I want to be very clear that our decision to re-engage sectors is going to be based on the best facts and the best science, and what facts and science have told us is that re-engaging our state too soon or too fast will lead to a second wave of COVID-19 in Michigan," she said. "During the flu pandemic of 1918, some cities lifted social distancing measures too fast, too soon, and created a second wave of pandemic."

Whitmer said that as a result of lifting social distancing measures too fast in 1918, many cities had to revert to quarantines and "suffered a lot of additional deaths." 

We will explain the source of her data, which comes from an academic paper in 2007. 

The influenza pandemic of 1918 spread worldwide and killed at least 50 million people, including about 675,000 in the United States. Since there was no vaccine for the virus and no antibiotics to treat secondary bacterial infections, control efforts were largely limited to social distancing and quarantines, which were applied unevenly.

During her press conference, Whitmer pointed to a chart by National Geographic, which displayed the findings of a 2007 study about the death rates in 43 cities during the 1918 pandemic. The study was published in the Journal of the American Medical Association and written by researchers from the University of Michigan Medical School and the U.S. Centers for Disease Control and Prevention. 

Two of the authors summarized their findings in the Washington Post in April.

"The experience of 1918 also reminds us that early, layered (i.e., more than one at the same time) and lengthy mitigation measures are the best strategy. For social distancing to work, it must be sweeping and enforced across a wide swath of the community," wrote Howard Markel and J. Alexander Navarro.

The researchers examined social distancing in 43 cities during about 24 weeks in 1918-19. Public gathering bans typically meant the closure of saloons, public entertainment venues and sporting events. Indoor gatherings were banned or moved outdoors. 

Researchers found that cities that implemented social distancing in a timely and comprehensive manner and sustained those rules suffered the least.

St. Louis, for example, implemented a relatively early, layered strategy that included school closures and the cancellation of public gatherings. It sustained those interventions for about 10 weeks and did not experience nearly as harmful an outbreak as 36 other communities. 

Conversely, Philadelphia held a massive Liberty Bond Parade to bolster the World War I effort. That led to a spike of thousands of flu cases within days. In Atlanta, the mayor sided with the business community and ended closures after three weeks, despite objections from the board of health. The epidemic raged in Atlanta.

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Researchers documented public pressure to end social distancing as soon as the flu seemed to peak and ebb. Cities then lifted the measures, and people lined up for movies and packed into dance halls and shopping districts.

"The result? Cases and deaths resurged. Most cities closed their schools once again," the researchers wrote. 

Researchers noted caveats including that there could be errors in the historical record and the difficulties in interpreting data from 90 years ago. 

Navarro, one of the study authors, told PolitiFact that the study shows that communities must be very careful about removing social distancing restrictions too soon. Social distancing flattens the curve, but it doesn’t end the epidemic. It ends when a community  reaches hard immunity through vaccine or antibody reaction from infection.

A separate paper published in 2007 in the Proceedings of the National Academy of Sciences examined 17 U.S. cities during the flu pandemic. It found that cities in which interventions were implemented early had peak death rates about 50% lower than those that did not. It concluded that social distancing and other measures "can significantly reduce influenza transmission, but that viral spread will be renewed upon relaxation of such measures."

It’s tricky to compare lifting restrictions "too early" with "holding them for longer," said Marc Lipsitch, a Harvard epidemiologist and one of the co-authors of the National Academy of Sciences paper. In either case, there will be some amount of resurgence once social distancing is let up.

A recent paper he co-authored in Science suggested that a single period of distancing could not permanently solve the problem; prolonged or intermittent social distancing may be necessary into 2022.

"So overall, the problem is that it's not short vs. long, but single vs. repeated (or some other strategy such as a vaccine)," he told PolitiFact.

On April 15, President Donald Trump said he thinks some states can open up before May 1. Many scientists have warned that ending the interventions prematurely will lead to more deaths.

Dr Anthony Fauci, the country’s top infectious disease expert, told the Associated Press on April 14 that the U.S. doesn’t yet have the contact tracing and testing needed to reopen the economy. He said Trump’s goal was a "bit overly optimistic" for parts of the country. 

"I’ll guarantee you, once you start pulling back there will be infections. It’s how you deal with the infections that’s going count," Fauci told the AP.

Whitmer said, "During the flu pandemic of 1918, some cities lifted social distancing measures too fast, too soon, and created a second wave of pandemic."

Typically, when social distancing ends, there is a second wave. The goal is to make the second wave as small as possible. Whitmer pointed to research from the University of Michigan in 2007 that found after social distancing rules ended in many cities, cases and deaths surged. 

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