If #Corona is responsive to weather (thus seasonal), optimal response might be seasonal. In particular, a period of lockdown, left on its own, can sometimes make things *worse*, because lockdown can push the peak of the epidemic to the "wrong" season. A simple simulation (1/N):

I use a standard SIR model (& one SEIR calibrated by Corona). 2 simulations: (1) where contact rate is at 1 (baseline), 1st fig, red, and (2) contact rate is reduced to to 0.5 (lockdown) for days 60-102 of epidemic (6 weeks) & back to 0.9 for the rest of the time, the blue. (2/N)

Effective infectiousness is contract rate times seasonal effect (2nd figure from top). Clearly blue has lower contact rate and infectiousness *at all times*. But 3rd and 4th figure from top show that more people get infected and die under the blue! (3/N)

This is because first peak under red is at a "good season" (lowest infection rate season), and the second wave becomes smaller because of herd immunity. The blue "pushes" the peak to the "wrong season" (peak of seasonality) and thus the peak is reinforced. (4/N)

Of course, this doesn't mean lockdown or social distancing are bad. It simply means we cannot be locked for 6 weeks and wash our hands after that and be "good to go!" A long menu of policies are needed to keep R<1 and the optimal policy might be seasonal. (5/N)

For instance, should we partially open schools in summer and close them in winter?! In sum, the hammer & the dance is needed for a long time and to do it optimally, we have to understand seasonality, patterns of diffusion & the structure of the human contact network. (N/N)