Lockdown slowed Covid-19 spread significantly

THE lockdown imposed by the government since March 12 has been successful in combating the coronavirus pandemic in the country, according to a May 20 report by a team of eight University of the Philippines professors.* The group has been monitoring the pandemic since April and has produced seven reports so far — the projections of which have been largely accurate.

“The past enhanced community quarantine has been critical in reducing transmission and deaths due to Covid-19 in the Philippines,” the report said. “We know this because the reproduction number ‘R,’ which measures the rate of spread of the pandemic, has been decreasing since the beginning of ECQ.”

A value of R, also called R0 (“R naught”) of more than 1 indicates that the pandemic is spreading and the number of new Covid-19 cases is increasing, while R less than 1 indicates this number is decreasing.

Reproduction number going down since lockdown

“The reproduction number R has been decreasing since April 1, from 2.5 to less than 1 currently,” the report pointed out (see accompanying figure).“ Based on our data, the value of R for the entire Philippines has been decreasing, and in a number of provinces around the country, the spread of Covid-19 is either controlled or in a decelerating trend. ECQ was successful despite limited testing and contact tracing in the country. It does not mean, however, that the positive trend is irreversible.”

“The decrease in the reproduction number may be solely attributed to the enhanced community quarantine despite some challenges the nation faced with regard to mass testing and contact tracing. On the other hand, the nationwide trend only shows the average for the entire country. Trends vary according to region, province and local government unit. It is towards this end that there has always been a need for more granular analysis of the pandemic.”

The study reported that nearly two-thirds (64 percent) of Covid-10 cases (on May 16) in the country were in the National Capital Region (NCR).

The study grouped NCR cities into three: Those with the most number of Covid-19 cases in NCR (Group A); with the least number of cases (Group C), and those in between (Group B):

– Group A: Quezon City, Manila, Parañaque, Makati, Mandaluyong and Pasig

– Group B: Taguig, Caloocan, Pasay, San Juan, Las Piñas and Muntinlupa

– Group C: Marikina, Valenzuela, Malabon, Navotas and Pateros.

However, even if ECQ is maintained, the study forecast that Covid-19 cases and deaths due to the disease would be increasing, with Quezon City and Manila still the two main hotspots in the metropolis (See Table 1).

Outside NCR, it was mainly the cases in Cebu City, totaling 1,544 as of May 16, that have been driving up the nationwide figures, with the entire province of Laguna a far second with 410 cases. The study’s forecasts on the disease in five areas are in Table 2.

Using the calculated values of R and the number of new daily Covid-19 cases per million of population, the study estimated the level of risk in the country’s provinces and cities.

A province or local government unit (LGU) is considered to be “high risk” if R is greater than 1 and the number of new Covid-19 cases per day is greater than 1 per million of population. A province or LGU is considered “medium risk” if the number of new Covid-19 cases per day is greater than 1 per million of population and R is less than 1.

A province or LGU is considered “low risk” if the number of new Covid-19 cases per day is less than 1 per million of population.

Low Risk: Albay; Antique, Bataan, Benguet, Bulacan, Camarines Norte, Camarines Sur, Cavite, Ifugao, Iloilo, Lanao del Norte, Misamis Oriental, Nueva Ecija, Occidental Mindoro, Pampanga, Quezon, Rizal, Romblon, Tarlac and Cebu province (not including Cebu City, Mandaue City, LapuLapu City).

Medium Risk: LapuLapu City, Laguna, Mandaue City, Oriental Mindoro and Samar.

High Risk: Batangas, Cebu City, Davao City, NCR, Zamboanga City.

All other provinces not mentioned in this list had no new Covid-19 cases from May 10 to 16, and put in the “Safe” category.

On Wednesday, the team’s recommendations.

* Guido David, PhD Mathematics; Ranjit Singh Rye, MPA; Ma. Patricia Agbulos, MBM; with contributions from Erwin Alampay, PhD Emmanuel Lallana, PhD; Rodrigo Angelo Ong, MD; Elmer Soriano, MD and MPA; and Benjamin Vallejo Jr. PhD


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