Worldfocus’ special report on the H1N1 flu outbreak traced the evolution of an epidemic around the world, from the first days in Mexico to the far reaches of the globe.
Stephen Morse, a professor of clinical epidemiology at Columbia University’s Mailman School of Public Health, discusses how he sees the H1N1 flu epidemic playing out over the next few months in Mexico, the U.S. and the world.
Below, Professor Morse answers viewer questions. Thank you for your submissions.
William in New York asks: How do people become infected with the swine flu? Is it airborne, is it
contact with a person or an object an infected person has touched, or both?
Professor Morse: Probably mostly airborne. The swine flu is exactly like the regular flu we’re all familiar with in its physical properties and transmission.
It’s hard to believe, but after all these years of studying –- and experiencing — the flu, we still aren’t absolutely sure about all the mechanisms of transmission. But we can make some good estimates. I suspect that most infections are probably airborne, especially when people cough or sneeze nearby. Contact or inanimate objects are probably much less important as ways to become infected, although it’s still an open question and may account for some cases.
Because of the airborne spread, cover your coughs and sneezes (and if you can, throw away the tissue and wash your hands afterwards), and if possible stay at least several feet away from people who are coughing or sneezing. Because of the possibility of contact transmission, we also recommend good “hand hygiene” –- washing your hands (or using a hand sanitizer) regularly. We’re not sure whether or not handwashing makes a big difference with flu transmission, but it has clearly been shown to prevent many other infections and is a good simple precaution.
James in Michigan asks: The virus has three different strains of D.N.A — human, avian and pig. Can it jump from species to species, if the virus is compatible with the species? If so, shouldn’t we be concerned about that?
Professor Morse: Influenza viruses are exchanging genes all the time, often without our noticing until disease occurs. Influenza Type A — the one we usually are referring to — has its genome divided into eight segments of RNA (you can think of them as “mini-chromosomes”). The segments make it easier for the influenza viruses to exchange genes, a process we call reassortment. This is the process that usually gives us new pandemic strains. The widest variety of influenza viruses live in waterfowl, such as wild ducks or geese, and the novel gene in a pandemic usually ultimately comes from this source. However, humans are generally very resistant to infection by these avian (bird) influenza viruses. Pigs may be more easily infected and serve as a sort of “mixing vessel,” because they can also get infected with flu viruses from mammals, including pigs and humans. When two influenza viruses infect the same host (individual), they produce new descendants that may swap gene segments at random as they’re being produced, resulting in many different combinations. Some of them, as a result, just happen to have the right combination of genes to infect other species (like humans) that the parent viruses couldn’t infect.
This particular “triple reassortant” we’ve been hearing about as the ancestor of this virus was first identified over 10 years ago, in U.S. pigs, and has been in swine for at least the last decade.
Lynda in Texas asks: Will the pneumonia shot help with a secondary infection from H1N1?
Professor Morse: Yes. This shot protects against a type of bacterial pneumonia that used to be a major secondary infection, and a common cause of death in those elderly who had serious medical conditions. This vaccine prevents “pneumococcal pneumonia”, caused by a particular species of bacteria that is very common in the human population and has been a real killer in the past. So it will help. However, there are other causes of secondary infection that are not covered by the vaccine, so call your doctor if you get the flu and don’t start improving in a few days, or if you think you might have a secondary infection.
Spirit in New York asks: How concerned should I be about traveling on the subway, bus or train to another state? Is public transportation safe?
Professor Morse: No reason to worry at this time. There isn’t much risk from public transportation within the U.S., and that’s not likely to change until the flu becomes much more widespread. As of now, the virus is simply not widespread enough and there are not enough cases to make public transportation a major concern for infection. Public transportation, in general, is probably about the same risk as most places where people gather for similar periods of time.
Gerald in Connecticut asks: Our daughter is scheduled to leave for Mexico this Saturday on her honeymoon. Would you recommend she not go?
Professor Morse: This is really a personal choice, and I can empathize with her dilemma.
The CDC (Centers for Disease Control & Prevention) recommends avoiding all non-essential travel to Mexico if possible. Additional information and the latest updates are on the CDC Web site.
The risk is probably very small, but the newlyweds may well enjoy their honeymoon more if they aren’t distracted by the concerns about catching the flu. If your they do decide to go, they should check on their transportation arrangements. Many U.S. airlines are still flying to Mexico, but with reduced schedules because there are fewer passengers. Most airlines appear willing to give refunds or cfredits for those who want to delay the trip.
Aside from Mexico, travel restrictions to other places are generally not warranted at this time. There is a natural tendency to want to close borders or limit travel everywhere when these disease reports come up, but restrictions are often too late, after the disease has already spread into the country. By then, travel restrictions are usually too late to really prevent spread.
Nathan in California asks: Is it possible there will be an increased spread of the H1N1 virus later this year during flu season?
Professor Morse: Yes, it is possible, although truthfully we don’t know what it will do. Flu is notoriously hard to predict, so those of us who work with the virus have a healthy respect for its variety and unpredictability. The possibility of the virus coming back in another wave (possibly even causing more severe disease) later in the year is one possible scenario. But this is unpredictable, and that’s why it’s very important for epidemiologists and public health people to watch influenza activity carefully and be prepared to act appropriately if something happens. Keep watching the media for new developments.
Vernell in Texas asks: What can be done to prepare in advance of a possible return of the
disease in the fall?
Professor Morse: First, stay well informed in case there’s a major change or sudden development in the flu situation. If the situation is unusual, there may be special recommendations.
Otherwise, basically prepare the way you usually do for the flu. The hygiene measures we’re recommending — basics such as “respiratory etiquette” (covering coughs and sneezes), regular handwashing, staying away as much as possible from people sick with the flu, and staying home if you think you have the flu — will apply whatever happens. Call your doctor or health department information line immediately if you’re having difficulty breathing, feeling a lot sicker than you think you’d normally be with the flu, or if you start getting worse instead of better. You may want to have some extra supplies of food and other basics at home in case you have to stay in for a while.
A vaccine may be available by next fall, and you should seriously consider whether you want to take it. Your doctor can help with this decision.
Many people ask about antivirals, like “Tamiflu”. In general, these drugs can be lifesaving in severe cases if we give them fairly early in the course of disease (within the first 48 hours), but have relatively little benefit in mild or moderate flu (which will get better without medication). We don’t encourage these drugs for mild cases, because we’re concerned that wide use might cause more rapid development of viral resistance to the drug.
Wishing you good health!
Disclaimer: Stephen Morse provides information and informed opinion, not medical advice.