The annual flu season is in full career across most of the country and parts of California have been particularly hard hit. We reached out to Arthur Reingold, head of epidemiology at UC Berkeley’s School of Public Health, for some answers about the nature of the influenza virus, what we can do to control it, and the risk of another flu pandemic like the one of 1918.
CALIFORNIA Magazine: A striking feature of the flu is that we (meaning the general public) don’t take it all that seriously, and yet it kills tens of thousands of people every year in the U.S. alone—including many who are young and seemingly healthy. Why do you think there’s that disconnect?
Arthur Reingold: It’s due to a lack of understanding and information about influenza as a disease and confusion of it with the common cold. There are many misconceptions regarding the safety of influenza vaccine, which many seem to believe can or will give you the flu, which with the injectable (killed) vaccine is impossible. The fact that the vaccine sometimes has sub-optimal effectiveness also contributes, as does fear of needles, distrust of medical experts, the pharmaceutical industry, government, and so on.
CM: We associate the flu virus with fall and winter. Where does the flu go in the summer?
AR: No one really knows, but the flu viruses that infect humans are always circulating somewhere, either in the Northern Hemisphere during our winter, the Southern Hemisphere during their winter, or in countries closer to the equator, in some of which they seem to circulate throughout much of the year. So, there is probably spread and reintroduction always taking place. And there are the influenza viruses that circulate in pigs, wild and domesticated birds, etc., which are always circulating and which often exchange genetic information with the strains that infect people.
CM: This is the centennial of the flu pandemic of 1918, which is estimated to have killed at least 50 million people, more than died in both world wars combined. What’s the difference between seasonal flu epidemics like the one we’re experiencing now and flu pandemics like we had then? Is there a potential for every seasonal flu to become a pandemic?
AR: There is the potential for us to have a flu pandemic in any given year, and no one can currently predict when we will have one, as opposed to the certainty of having a peak of influenza (“annual epidemics”) every year. Neither can we predict which flu virus will cause the next pandemic a lá 1918, so “being prepared for a pandemic “ is difficult in terms of making and stockpiling vaccine.
CM: Reports are now coming from hospitals in California that are overwhelmed with flu patients. San Diego County alone has reported 142 deaths so far. Should we be worried that this year’s flu could become a large-scale public health crisis?
AR: It’s possible, but I suspect not. It is certainly swamping clinics and ERs.
CM: According to figures from the Centers for Disease Control, only about 40 percent of Americans get the flu vaccine, at least early in the season. How far is that figure from so-called herd immunity? And is herd immunity really achievable with flu?
AR: Herd immunity is achievable for influenza, because it is not nearly as transmissible as measles or whooping cough. A key factor is achieving reasonable levels of immunity among young children, who do much of the transmitting to adults, the elderly, and infants. Japan showed some years ago that achieving high-level coverage of school children can be very effective in tamping down population-wide influenza. So, it isn’t just the percentage of the total population vaccinated, but the percentage of certain subpopulations that matters, as well as the effectiveness of the vaccine in a given year.
CM: News reports say this year’s flu vaccine is only about 30 percent effective. Why get it then?
AR: We hope it will be about 30 percent against the H3N2 strain causing most of the illness, and higher against any H1N1 or B strains. The quick answer to your question is that even 30 percent is better than nothing, and vaccination is probably the most effective preventive measure we have against flu.
CM: In 1918 the main public health response to the flu pandemic was the wearing of masks which were mass manufactured and in many places, including the UC Berkeley campus, were ordered to be worn at all times indoors. Are masks effective in guarding against flu exposure and transmission?
AR: A well-fitted N-95 mask is effective, but most people wear poorly fitted “surgical masks,” which may or may not work as well. The evidence is not as strong. And it’s best to put them on people who are ill and out and about than on those who are well.
CM: A recent New York Times editorial bemoaned the lack of resources in support of the search for a universal flu vaccine, a single shot that would protect against all strains of influenza. Given the high rate of mutations in flu strains, how likely are we to meet that challenge?
AR: No one currently knows how to do it, so it is impossible to predict how long it will take—if it can be achieved at all. People were predicting we would have an effective HIV vaccine within 10 years some 30 years ago, and we still don’t how to make one of those either. Bottom line, we don’t know.