In the OCTA National Report dated February 17, 2021, the OCTA Research Team presented a mathematical projection with the description:
“If restrictions in NCR are relaxed to very loose levels, the region will be under a constant threat of a surge due to the increased mobility of people, reduced social distancing, and diminished compliance with health protocols, as was observed at the outset of the December holidays…. For this model, we use the reproduction number Rt = 1.6 observed in Cebu City, which is comparable to the reproduction number observed in Mountain Province and Kalinga, when new cases increased in January. Under these assumptions, NCR will reach 2,400 new cases per day by March 26, a window [of] just 36 days.”
In the chart below, we plot the projections made on February 17, given by the blue line, on top of the actual number of cases reported in NCR to date, denoted by the green columns.
1. Although the shift to MGCQ in NCR was not approved, quarantine restrictions were eased.
2. The rise in new cases in NCR began around that time, as can be observed in the chart.
3. The projections made on February 17 have so far approximately matched the actual number of daily new cases reported by DOH.
4. The reproduction number in NCR has increased to Rt = 1.66 as of March 6, nearly the same value of Rt = 1.6 used in the February 17 projections.
5. Under the current trends, NCR is projected to have around 2,400 new cases per day by March 26, which also matches the projections made on February 17.
Guido David is an OCTA research fellow, and a math professor at the University of the Philippines Diliman.