What factors do policy makers use to decide if COVID related lockdowns can be lifted?

Have been reading up on what will be the key metrics to decide lockdown relaxation by policy makers.

While we are hearing about Red / Yellow / Green zones based on case density, what I learnt is two key R numbers relevant for any epidemic — R0 and Re.

R0 -The basic reproduction number. The number of people an infected person impacts at the start of an epidemic. So if at the start of Covid, if one person infected 2 others, R0 is 2.

If R0 > 1 in any population (at any geographical level), then cases will increase exponentially. If R0 <1, then spread is much slower and the virus may even die out.

R0 is an estimate based on data collected and models developed by experts.

· % of susceptible people and density of the population

· Infectiousness of virus

· Rate of recovery, death, period of infection-ability

Re — The Effective Reproduction Number. The number of people who can be infected by an affected person at any time (also called Rt).

As % of susceptible people falls (due to death, recovery), as some people get immunity, Re falls with time.

There is some interesting math to relate R0, Re to “Herd Immunity” and % of population that has to be immunised. I wont go into that. Interested folks can read here — https://www.cebm.net/covid-19/when-will-it-be-over-an-introduction-to-viral-reproduction-numbers-r0-and-re/

India’s R0 is around 1.3 to 1.5 range presently, as computed by some scientists. Link here — https://theprint.in/health/indias-r0-lowers-further-to-1-29-say-scientists-predict-covid-cases-at-30000-by-3-may/411421/

So can our policy makers risk lifting the lockdown with R0 > 1 ? Without significant testing in place? Without significant means to isolate / trace contacts in place?

My answer is NO. Lockdown will get extended to 3.0.

Lockdown 3.0 will have a long-term debilitating impact on our economy, jobs (expect many layoffs in May) and livelihoods unless our government moves fast and infuses massive liquidity / financial stimulus to get consumer demand / spend going.