Those words in quotes are trigger words for concern about coronavirus and, because shortly after my return I developed a screaming cold, I started to think about the risk of exposure to such a more-serious infection.

From the point of view of beer itself the risk of infection is zero. Beer is an acid product (pH about 4.2 or so) and contains alcohol and so does not support the survival of pathogens. Beer in a clean glass held by clean hands is a safe drink even in risky places. So is wine of course for the same reasons. However, I was at a bar-restaurant the other evening and observed the crowd behavior that was a pea soup of potential cross contamination and infection. Several small tables had half-a-dozen people crowded around them having a good time with their heads close together laughing and talking loudly over the background noise. In a pub about the only thing not likely to carry infection is the beer itself. The behavior it encourages, on the other hand, plainly favors infection and in such groups anything some persons carry their friends may inherit.

Anheuser-BuschInbev has announced sharply reduced estimates of its profits going forward because, all over the world, people are avoiding crowded environments including pubs. However, I see for the time being, no clear evidence of that locally. Incidentally, Corona beer and the virus have no connection and nothing in common except the name, despite the fact a market survey suggests a lot of people think it does. Chinese food is also safe. 

I began to think more broadly about the opportunity for infection in Davis and immediately congratulated myself on being surrounded by many square miles of bare earth waiting to become tomato or sunflower fields. These protect me from forest fires and floods and should ward off infection as they separate me from intense areas of population. Well, not quite. The UCDavis campus with its diverse student, staff and faculty populations and their far-flung interests is an open door to the world, attracting visitors to and from many foreign nations, not the least of which is China. Although my time on campus is miniscule these days those many travellers are in our community.

On the other hand, the chances are small indeed of infectious contact.

That confidence was rattled by the recent identification of an infected person in northern California. That relatively vast area suddenly became a good deal smaller, even local, when I learned the afflicted person was from Solano County and is now under care at UCMed in Sacramento. That turned out to be the good news. The bad news is that this infection is the first to have no obvious connection to China or other infected person. It’s called community infection and implies that the virus is loose in the population. That’s not a good but perhaps an inevitable step in the evolution of a pandemic. It will be interesting if or when the second such infection shows up in Solano County.

I need a beer to think about this for a moment.

Part of my reading while traveling was book by Dr. Kit Yates of Bath University in the UK called The Math of Life and Death. Dr. Yates is an expert in the application of mathematics to biology. It’s a fascinating read. The seventh principle of the seven explored in the book is chapter sub-titled How to Stop an Epidemic. Turns out there is a whole field of study devoted to mathematical epidemiology which, properly utilized, can help us predict the course of an epidemic, guide us to the best way of stopping it and the most efficient ways to deploy resources to achieve this end.

The history of this crucial mathematical development dates back to the late 1890s and early 1900s when plague invaded India and ultimately slaughtered millions. Anderson McKendrick, a young military physician, observed and studied this event. Later, he with William Kermack invented the S-I-R model of disease progression in which S are sensitives, I are infectives and R are removeds (dead or recovered immune). From this approach many more sophisticated and useful models are now derived, of which I’m sure, our public health experts are well aware.

R0 or R-zero might refer literally to the first person to contract the disease, for example the first person infected with Ebola is known by name, or represent the number of other people each infected person can infect. If R0 = 1.0 or less the disease will putter out. But at 2 it might grow exponentially 1>2>4>8>16 and so on. I was interested that measles has an R0 of 12 to18 compared to coronavirus (apparently) at 2 to 3; the greater the value of R0 the more difficult it is to achieve herd immunity by vaccination. This explains why relatively few anti-vaxxers have caused a comeback of that childhood favorite, measles.

I understand why A-B-Inbev with its global interest in beer sales would suffer a downturn in profits based on people’s changed behavior. Although I do not see a similar urge among pub-goers here, for the time being, it’s likely that those operations dependent on income from taprooms or brewpubs might suffer first, as customers start to avoid crowded places. Brewers who sell substantially through retail outlets seem more immune to that effect and, at the margins, might even prosper from it as consumers switch to drinking beer at home. 

Relax. Have a beer. Chances of infection are low but not zero and so simple but effective precautions seem sufficient for now. And I guarantee its OK to enjoy a Corona beer with your Kung Pao Chicken.

Michael J. Lewis, Ph.D., is professor emeritus of brewing science at the University of California, Davis, and the academic director and lead instructor of UC Davis Extension’s Professional Brewing Programs. Lewis has been honored with the Master Brewers Association of the Americas’ Award of Merit and the Brewers Association’s Recognition Award. He is an elected fellow of the Institute of Brewing & Distilling. He is also a recipient of the UC Davis Distinguished Teaching Award.  He can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it.