Past plagues, current pandemics, and public hygiene messaging

History Ph.D. candidate Sarah Xia Yu discusses her research on public hygiene in China and what the past might tell us about how governments could better communicate public health messages.

Woman leans against a tree with her arms crossed, looking into the camera, with other trees in fall colors behind her on a sunny day
History Ph.D. Candidate Sarah Xia Yu’s research looks at public health and hygiene in Republican China.

As the COVID-19 pandemic was starting its sweep across the globe in February 2020, history Ph.D. candidate Sarah Yu was set to return to Penn after spending six months traveling around Asia doing research for her dissertation on public hygiene in China.

“I came back to the U.S. from my main research trip just a week before travel from China was banned,” she says. “If I’d arranged to come back any later I don’t know what would have happened.”

The topic of her dissertation, provisionally titled “Hygiene and daily life in Republican China,” was suddenly extremely timely, as governments around the world tried to persuade citizens to change their behavior and halt the transmission of the virus.

“I look at different forms of grassroots reform movements, local governance, and community leadership that convinced people to adopt habits in their daily lives that pertain to hygiene,” she says. “These were often things that were inspired by global medical progress, but also based on local traditions and what every small community needed at the time. They were often phrased and taught to people in a way that made sense to them in terms of what kind of tangible benefits they were going to be able to get from changing their daily habits.”

Penn Today spoke with Yu about her research, what historic parallels she’s found to current pandemic responses, and what the past might tell us about how governments could better communicate public health messages.

As you were embarking on this area of study, a pandemic swept the globe. How did this affect your research?

One of the first pieces I wrote upon my return from Asia emphasized that we’re all living through a pandemic in a way that is bewildering. Regardless of whatever progress in high level technology that we've made in the last 100 or 200 years, we still have a situation where the people who are primary care doctors aren't talking to the people who are making policies. There is a medical issue and there is a public issue, and they don’t know how to communicate these two things to each other.

There was a lot of resonance with my own research at the start of the pandemic. I had just spent six months across Asia reading about how in the 1920s people who founded medical schools in China were thinking about the very question of how to communicate these messages. Founders of the Peking Union Medical College had built a high-class medical facility and surgery rooms and they were training people to be doctors on par with anyone trained in the United States. And yet, people weren’t coming to the hospital. It was this sort of communication disjuncture that I kept seeing back then, and still today, that helped me refine my research direction. It helped me focus, but to be honest I was a little bummed out for a while because it seemed to me like nothing in public health had changed.

We’re still dealing with issues arising from individuals asking, ‘Why is my personal behavior related to something that's going on in the outside world?’ Different governments around the globe have been trying all kinds of measures to stop the pandemic, and we’re still not having the best messaging for public health interventions.

The pandemic reinforced that my work was telling a story that needed to be told. Not just the narrative but also the way that problems ultimately were solved, or not, at the local level in China in the early 20th century. When these reformers wanted people to change their behavior, they didn’t say it was because of ‘science’ or ‘medicine’ because those words don’t really mean anything to the general population. And we see today that the invocation of scientific progress still doesn’t appeal to everyone in the same way as we would like.

People wearing medical gear and medical face masks stand in front of a Chinese temple in 1918
A doctor and his team in Datong, China, in February 1918.(Image: Courtesy of Lorenzo Morgan Papers, Presbyterian Historical Society, Philadelphia)

What are some parallels to what you’ve seen in past plagues or epidemics that you are seeing during COVID-19?

One parallel that I thought was really fascinating involves mask wearing. It’s become such a controversial practice, as there’s so much signaling that goes on when you see who’s wearing a mask and who’s not. I wrote about this briefly in an article for the Harvard Library Bulletin. They asked me to comment on some of the photos from the Manchurian plague epidemic of 1910-1911. This was the first time that masks were used as a way of preventing a respiratory disease and recommended for the general public.

If you’re looking at these photos of the plague from the early 20th century, everyone who’s wearing a mask is dressed in a uniform that looks exactly the same. From the outside you cannot tell who they are or where they’re from, which was important because the experts who were tasked with controlling the plague were from different countries; there were Chinese, Americans, Japanese and Russians, and each group had their own geopolitical concerns in Manchuria. The mask and the uniform demonstrated that they were part of this elite group of scientists. It established a canon for medical professionals across the board about how they should be presenting themselves.

In a modern-day perspective, masks can signal things like what side of the political spectrum we’re on or what degree of advanced scientific knowledge we claim to have. It becomes more apparent not just with mask wearing but also with how you're wearing the mask and what kind of mask it is. You can tell if someone has shelled out extra dollars for a KN95 or if they’re wearing a really dirty cloth mask or if they’re wearing it under their nose.

Now that this medical dress code has become public, it’s important to realize that we’re actively looking for those signs before we talk to somebody. We may think that’s new because we’re more politicized and polarized now, but I disagree. I can imagine if you were alive in 1911 and there was a massive plague epidemic going on, you would also want to be able to determine who seems to be someone you can trust who cares about your well-being and is following the guidance that is coming down from above.

When you see news footage of school board meetings with angry debates about face mask mandates and protests against vaccinations, what are your thoughts?

Throughout history, there have been people pushing back against any required change in their behavior. I was recently looking through a 1924 guidebook on wholesale vaccination against cholera, and there were all these guidelines saying, ‘These are auspicious days to vaccinate people; here’s when you cannot vaccinate people,’ or ‘This month is good because people are not wearing bulky clothing so they can roll up their sleeves, or now is a good time as they don’t have to go out in the fields to harvest food because their arms will hurt the next day.’

It stressed taking a vaccine was always something medical professionals had to explain to people, and then let them know what they would get out of it. Will someone come to their house to check up on them for the next couple of days? Will they get the injection and then get a free lunch? Could they win a cash prize?

Nowadays, we want to appeal to people to get vaccinated against COVID-19 because it’s the right thing to do. That’s never really worked in the past. For COVID-19, the Pennsylvania government promised to open up once a certain amount of people were vaccinated. Going to concerts and restaurants was evidently enough incentive for a lot of people but clearly not all.

I’m always looking for historical examples of successful appeals. What was enough to make people change their behavior?

Shame works sometimes. My research focuses on a time when China was going through a lot of political changes with the government at the top, but many parts of China had still been leased to or sold to foreign governments that had won wars against China. Researching this period of time, I’ll often read an editorial that says, ‘We were a major civilization, and now we’re a weak country, and infectious disease control is something we have to do to change to regain the greatness.’

Sometimes that kind of shame appeals to people on an individual level. Sometimes it really does take a free meal or cash prize to make people turn out.

What is the most important thing for people to know about this topic?

The only thing that seems to bring people together is what’s in it for them. For as long as there have been vaccinations, there have been the vaccine hesitant.

There are all kinds of reasons for being skeptical, be it general hesitancy, distrust of modern medical professionals or maybe they just don’t like the person who came to their door because their accent was weird.

At the end of the day, I’ve found that people are still driven by pretty simple motivations, which seems surprising, but I don’t think of it as necessarily alarming. I think that’s pretty rational behavior.