| With this current outbreak, it's surprising how quickly the sum total of information you receive, can cause you to change your mind completely. Only 5 days ago, I was making the case for nationwide school closure. In the past 48 hours, I have gradually come to the conclusion that maybe we will get more longer term benefits by being more conservative in activating community mitigation.
The problem with public health, and interventions like community mitigation and school closure, is that you really need to act before you have real solid information (here's why), cos often by the time you know for sure, the window of opportunity for interventions to have significant effect would have closed. Thus, last week, as news of the first fatality AND 2 additional critically ill cases in the same state (Texas) came, it was entirely possible that we were seeing the beginning of a trend, of significant numbers of severe cases and ultimately deaths in all the other states that were just beginning to have outbreaks. In that scenario, if we had not acted fast enough, we would have had many dead kids by the time this wave is over.
In any case, the CDC were going on a more cautious path, giving guidance for state and local PH on school closure that seem to be gradually ramping up to more aggressive closures. Then King County, Seattle, where some of the most clued-up PH folks have done remarkable work on pandemic preparedness, announces that they are easing their response and will not be closing schools if cases are confirmed. The CDC also appears to be re-thinking their approach.
I can't speak for anyone else, but let me explain why I'm coming to different assessment than several days ago.
It's pretty clear to me that even though we may not call it that (yet) this has all the hallmarks of a pandemic virus. Apart from being a novel virus that has acquired the ability to transmit H2H, additional features being reported include
- efficient transmission within households with AR of 25-30%
- the flu activity is rising instead of falling, even though this should be the end of the flu season, ie the virus is now transmitted based on 'its own steam', regardless of seasonality.
- the age distribution for confirmed cases is atypical, with a median age of 17
- the age distribution of hospitalized cases is also atypical, mostly affecting older children and young adults
In previous pandemics, the virus tended to subside and come back later. In 1918 particularly, the first wave was mild, but the second and third waves were very deadly.
With all that in mind, we are faced with some tough choices in the current situation. Yes, there are outbreaks all over the US, but they mostly appear to be mild (35 hospitalizations reported). The bigger picture is, if this is a pandemic, then this virus is not going to go away. It's going to come back again and again, until all of us develop immunity, either from infection or vaccination. That is the hard fact we are up against, and not something we can prevent.
The biggest fear therefore, is not so much with the current outbreak, but what will happen in the fall. If it comes back in say September, and start a second wave with much higher lethality, is there anything we can do now to reduce mortality for the second wave?
We have been lucky, in being able to identify this outbreak, and observe it realtime. Although work on creating a vaccine has started, there are many uncertainties as to when we will see substantial quantities of vaccines being made available to the general public. Most estimates would say the first doses may be available in 4-6 months, ie maybe August to October. But that's just first doses, probably only enough for critical personnel or whatever. It will take more time to have enough vaccine for most people. Plus we may need 2 doses before there's enough immunity. We just don't know.
So if we start planning for what's going to happen in the fall, there's a significant chance that we will see a more severe outbreak but with no vaccine available for most people. What's more, the age distribution of having the most severe cases in young and healthy people, has been consistent in both Mexico and in the limited number of cases in the US and Canada. There's no reason to expect that pattern to change in the fall, which means teenagers and young adults will be at much higher risk if they catch the virus for the first time in the second wave in the fall, than if they have already been infected in this first wave.
Which means there may be a case to not damp down transmission so much, in this first wave, and let more people particularly school-aged youngsters, acquire some immunity by natural infection.
It's a tough choice, but I'm increasingly inclined to think it is the right one. |
