MSU public health expert discusses practices for mitigating spread of novel coronavirus

Felicia Wu, John A. Hannah Distinguished Professor at Michigan State University, explains the importance of adhering to public health guidelines.

It’s natural for humans to look to others for example. That’s why following others in adhering to public health guidelines, like physical distancing and wearing masks, is key in the time of coronavirus.

Felicia Wu
Felicia Wu, John A. Hannah Distinguished Professor in the MSU departments of Food Science and Human Nutrition, and Agricultural, Food and Resource Economics

Felicia Wu, John A. Hannah Distinguished Professor in the Michigan State University (MSU) departments of Food Science and Human Nutrition, and Agricultural, Food and Resource Economics (AFRE), has experience in analyzing public health impacts of humans following behaviors of those most similar to them.

Prior to joining the MSU College of Agriculture and Natural Resources faculty, Wu was an associate professor at the University of Pittsburgh Graduate School of Public Health. Her research there revealed that countries with similar food safety standards tended to engage in the most trade with one another. To conduct this research, Wu used social network models, which emphasize how connections among humans can contribute to behavior.

“It's about understanding that no human is an island, but we're all connected to other people, and how closely we are connected to people, and specifically, in what ways, influences the spread of ideas, the spread of information and behaviors, and unfortunately, also the spread of communicable diseases,” Wu said.

Face Masks and Physical Distancing

This principle — that humans mimic the behaviors and actions of those closest to them socially — can be applied to practices we now have to follow to prevent the spread of coronavirus.

“In the U.S., it used to be considered really taboo to wear a face mask,” Wu said. “At the beginning of the pandemic, people were still a little bit reluctant, until they began to see that everybody else was doing it. Just from taking walks around the neighborhood, you see people wearing face masks, and it's kind of a sense of relief. It's like, 'ok, it's acceptable for me to do the same.’

Social network theory can also be applied to physical distancing, or staying 6 feet away from individuals who don’t live in your household while in public. If we see people keeping 6 feet away from each other while on walks or in grocery stores, we’re more likely to do it ourselves.

“We all need to be participating in healthful behaviors, including the physical distancing, and wearing face masks when in spaces with other people, because overwhelming evidence has emerged that SARS-CoV-2 (the scientific name for the novel coronavirus) is highly infectious and transmissible through droplets in the air,” said Wu.

R0, or a reproductive number of a virus, is the number of other people you are likely to infect, on average, if you yourself are infected with that virus. According to research from the Los Alamos National Laboratory, R0 for the novel coronavirus could be as high as 5.7, meaning someone who is infected could spread the virus to nearly six other people. Other sources have estimated an R0 between 2 and 3. To put this number in perspective, R0 for the seasonal flu is about 1.2.

“As long as you have an R0 above 1, that means that that particular disease is not going to die away unless you take specific measures to reduce R0 to below one,” Wu said. “R0 is not a static number. It is different from location to location, and also different periods of time, depending on how much contact people have with one another and whether they take any protective measures to reduce infection.”

Creating Immunity

One commonly discussed way to reduce R0 for the novel coronavirus is increasing herd immunity, or the percentage of the population that needs to be immune to the virus so that a person who hasn’t already been infected can safely go out in public.

“Basically, there’s the implication that if there's sufficient herd immunity, then all of us can emerge from lockdown, that we can go back to life as we had before sheltering in place,” Wu said. “But it’s not that simple to reach herd immunity.”

The Los Alamos study estimated that 82% of the community needs to be immune to the novel coronavirus before all public health restrictions can be lifted, because their estimated R0 for SARS-CoV-2 is so high. The United States has a population of approximately 328 million people, so about 268 million people would have to develop immunity to the novel coronavirus in order to safely go out in society. Herd immunity for the seasonal flu is 55%.

The two ways to achieve herd immunity are through actually having been infected by the virus and gaining immunity to it, or receiving a vaccine. Obviously, if someone is infected, it increases their risk of death and/or sickness.

“We have to keep on exercising caution until we get that vaccine, or until there are sufficiently available and effective treatments that we deem that it's ok to go out in public and a certain fraction gets sick,” Wu said. "We can't accept the high rate of death that might result from widespread COVID-19 right now.”

There are several different types of vaccines for the novel coronavirus in the works, including traditional injections and microneedles, a patch with tiny needles that an individual receiving an injection would barely feel.

Wu emphasized that just because vaccines are in development doesn’t mean they’ll emerge quickly, although many are being fast-tracked.

In order to be made available for medical use, a vaccine must pass through three phases of clinical trials, according to the U.S. Centers for Disease Control and Prevention. In Phase I, small groups of people receive a trial of the vaccine to test for safety. Phase II is a broader clinical study where the vaccine is given to those who have characteristics (age, physical health) that resemble those the vaccine is targeting. In Phase III, the vaccine is administered to thousands of people to gauge for efficacy and safety.

If 268 million Americans need to be vaccinated to create immunity, that means at least 268 million vaccines need to be produced to be distributed in the United States — potentially more, if the vaccine requires multiple boosters. To complicate matters further, because the novel coronavirus seems to have a high R0, a large fraction of the population would need to get the vaccine to achieve the herd immunity to go about business as usual once again.

“I think that that's the part that some people haven't grasped about why it would take so long,” Wu said. “'Why might it take at least 18 months to roll out this vaccine?' Because vaccine candidates first need to be developed, and then they need to undergo stringent safety and efficacy testing over periods of time, and finally, the companies need to mass produce these vaccines so that all of us who want them can get them.”

Public Health Versus Economic Trade-Offs

Having effective medical treatments and public health practices is important for everyone, but especially essential workers, such as those in food industries (restaurants, grocery stores, processing plants, etc.), who are at disproportionate risk compared to the majority of the population. Wu is writing about this subject with fellow AFRE faculty members Trey Malone and Aleks Schafer.

“We all recognize that there is this economic versus public health tradeoff in opening businesses during a pandemic, and we are not insensitive to the needs of people who need to go out and work,” Wu said. “That is something we need to be concerned about from a social justice standpoint.”

Maslow’s Hierarchy of Needs organizes human needs into a five-tier pyramid: physiological, safety, love, belonging, self-esteem and self-actualization. The services deemed essential by Michigan governor Gretchen Whitmer tend to fall in the “physiological” and “safety” categories, which, as the base of the Maslow pyramid, are the most crucial.

“At the very base of the Maslow pyramid are the essential things that we, as individuals in a society, need to survive. One of them is food — food, water, air and shelter,” Wu said. “That’s why food has emerged as one of those areas that's essential business.”

Those who work in food industries could find it more difficult to adhere to social distancing guidelines. Meat packers are a group of particular concern, given that the work is in close physical space.

“Meat processing plants have emerged as high-risk workplaces during this pandemic, where the meat packers are working elbow-to-elbow with one another for long hours at a time in enclosed spaces,” Wu said. “In the past, we would just buy meat from the grocery store without thinking what went into making this meat available to us, what workers had to do to provide it. Now, these are the people that are falling sick.”

Reopening Society

The effects of the novel coronavirus have been devastating. However, there’s a possibility that the virus can re-emerge if the economy, and society at large, reopens too early. Balancing these ideals is the difficult task policymakers are facing.

“There’s a real risk of public gatherings, gatherings of large groups, that all the flattening we did is going to fail and cases are going to spike again,” Wu said.

Eventually, however, society will reopen. When it does, Wu believes we should follow the advice of former U.S. Food and Drug Commissioner David A. Kessler and abide by a social contract that will mean “fewer contacts with others and wearing protective gear.”

“A large fraction of us will all still need to keep on respecting distances,” Wu said, summarizing Kessler’s op-ed in the New York Times. “Those people that know they're in a population group that's more at risk, if Governor Whitmer or the federal government ever decided that it was ok for everybody to go out again, will need to recognize that they are at higher risk and to keep respecting physical distancing if possible, to protect their health. And also, those people that they're in contact with also need to be more careful — their children, their grandchildren, friends, co-workers, etc.

“Essentially, all of us need to continue to be careful — trusting in public health measures while waiting for medical advances to help this pandemic go away.”

Listen to Wu discuss the impacts of the novel coronavirus on AFRE's Closing Bell, hosted by Malone and Schaefer, and the Spartan Fireside Chat.

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