Laurie Garrett of the Council on Foreign Relations and a well-known authority on emerging infectious diseases was on PBS’s Newshour last night and she made a very important but little appreciated point. Mexico has made a major national sacrifice for global public health by shutting down its country and interrupting transmission of disease. The cost to Mexico has already been enormous it will continue to pay in other ways. The reputation of the government has suffered because of the way it handled this — the lack of transparency, the initial slow footedness (which of course it denies), its lack of credibility in the eyes of its citizens. There will continue to be a halo of risk and danger for an indeterminate time. And there will be the inevitable backlash against the government’s actions, which went from cold to scalding hot in a week. We are starting to see this in the US as well: the “overreaction” backlash. So it’s important to sort all of this out. What is the Big Picture at this point?
It’s now been a little over a week since swine flu (rebranded H1N1/2009) popped its head above water in southern California. From two cases discovered in mid-April in San Diego, the virus is now confirmed to have spread, mostly from Mexico, to 15 countries in North America, Europe and Asia. Confirming a case takes time so there are significant differences between reports of suspected, probable and confirmed cases, but as of this moment WHO acknowledges 17 deaths (16 in Mexico, 1 in the US) and confirmed 615 cases. The confirmed cases are new, not previously existing but unrecognized cases and there is clear and convincing evidence of person to person transmission. It appears the age distribution continues to be shifted toward younger age groups as compared to endemic seasonal influenza, probably a reflection of the fact that most people are immunologically naive to this flu virus. There remains an open question as to whether people who were born before 1957, the date that H2N2 replaced a previous H1N1 as the predominant subtype, may have some cross-reactivity to the current H1N1 strain. In any event, a novel influenza virus has spread quickly worldwide and is transmitting efficiently, pretty much the dictionary definition of a pandemic.
The extent and speed of spread is one factor of concern. The other is the clinical severity of the disease. The good news is that so far, clinically this influenza virus looks much like a mild seasonal influenza. “Mild” is a relative term. Any influenza infection is a potentially serious disease, and while we have no hard figures, good estimates of the excess mortality caused by influenza yearly in the US is around 35,000 to 40,000. These deaths and the significant but non-fatal illnesses that require hospitalization each flu season are the upper tails, the tip of the iceberg, of flu infections. Most people have milder cases. Some of these “milder” cases are still miserable affairs, with severe headache, joint and muscle aches and hacking coughs that can to on for weeks and malaise and tiredness lasting much longer. Some people are infected and have no symptoms at all. But the more people infected the more people who are in the upper tail of the distribution. You don’t have to shift the distribution much to double or triple the number of people in the tip of the iceberg (think of the tip as a pyramid, and as you raise the iceberg up slightly the new people are in its base, which is much wider). These are the people that will stress our already over stressed medical care system. US emergency departments are already overcapacity. They would break during a bad flu season.
So that’s where we are at this moment. There is some evidence from 1918 that cities that acted immediately to interrupt transmission by reducing opportunities for contact (“social distancing”) did better than those that didn’t. We would of course expect this on common sense grounds as well. That’s what Mexico has done — and I echo Laurie Garrett’s point, they have done so at great cost to everyone’s benefit. That is what is behind CDC’s recommendations that a school be closed as soon as a case is confirmed. There is a cost to that, too. Proms are canceled, to the deep disappointment of the prom go-ers and the economic loss of the venues and ancillary businesses. Exams are delayed. Child care needs for younger students produce a ripple effect throughout the community. And as in Mexico, these costs can produce a backlash if the public doesn’t understand why they have been incurred.
The irony is that the overreaction backlash will be more severe the more successful the public health measures are. If, for example, the virus peters out this spring because transmission was interrupted long enough for environmental conditions (whatever they are) to tip the balance against viral spread, CDC and local health officials will be accused of over reacting. It’s another example of the adage, “When public health works, nothing happens.” On the other hand, if local officials do nothing and things get worse, they will be accused of being slow.
It’s not just the current reputation of local officials that concern me, however. If this virus does wane with the summer months (something we expect to happen), it’s current mildness and its disappearance may lead citizens and decision makers back into the kind of reckless disregard of public health facts that has produced our current weak and brittle health infrastructure. But flu season will come again next fall, and it would be no scientific surprise if this strain is part of flu’s repertoire. Most of the world would still be unprotected unless we spend the interim preparing for the possibility it will reappear in a more serious clinical form (flu viruses are notorious for that kind of change). When I say prepare, I am not just talking about a vaccine, although that will be an important, but difficult< part. We will also need to invest urgently in a health care, public health and social infrastructure to absorb the consequences of potentially large scale absenteeism. We will also need to work out policies that will allow social distancing measures to work (child care, sick leave policy and other issues). It's an urgent task that must be started immediately. If there is an overreaction to perceived overreaction, the job of rationally preparing for a plausible near future event will be made much more difficult.