OCTA explains the science behind its COVID-19 pandemic model, projections – Manila bulletin
On Monday, August 9, members of the independent research group OCTA reported that the pandemic model they are using has been useful in providing trends in coronavirus disease (COVID-19) in the country.
OCTA researcher Dr Guido David said the number of reproductions is the main indicator used to study COVID trends.
He also cited that the positivity rate, which is the number of people who test positive given the tests, is also a strong indicator of support.
OCTA is also studying the use of healthcare to measure the impact of the pandemic.
“When the number of reproductions starts to increase, we need major interventions to prevent cases from swelling or to slow or decrease the number of reproductions,” David said in an online forum hosted by the Philippine American Academy. of Science and Engineering (PAASE).
“Some people argue that we shouldn’t be using the number of reproductions but it’s actually the indicator, it’s the variable that is used around the world to project the number of cases and determine the trends. Why is this the main indicator? Basically it measures the rate of infection. More importantly, it measures the speed or strength of the pandemic. This is why this number is very important. It’s like a temperature. If it is high, it means that things are bad. If it’s low, things get better, ”he explained.
David also pointed out that the number of reproductions is estimated based on the number of new cases using data from the Department of Health (DOH).
He said the DOH produces three pieces of data: the date of the report or the date the case was reported; the date of the specimen or the date the specimen was obtained; and the onset or onset date of the disease.
He cited data from July 1 to August 8, 2021, as an example, to explain that they are correlated.
“Here’s the picture if we line up the report date with the sample date two days ago and the start date three days ago. We can see that there is a pretty high level of correlation, ”he said. “If we use the report date, it’s very closely related to the start date of three days ago. Not 14 days ago some reviewers claim our data is flawed and unreliable. In fact, it’s very reliable as long as we understand that what we were looking at yesterday is minus three days, four days.
“Is this a big mistake or a problem?” No. Because first of all we understand that what we are looking at is actually three to four days old, and that’s fine. It’s not a big change in our projections, ”he added.
David further explained that the case reports can be used to calculate the reproduction number even given the three day lag.
In the event of a power surge, it serves as a lower estimate of the true number of reproductions, he added.
For his part, OCTA scholar and biologist Fr. Nicanor Austriaco said the group’s pandemic model was “useful”, citing OCTA’s forecast scenarios for Metro Manila hospitals that they would exceed critical capacity by mid-August.
Based on projections made on July 28, 2021, Austriaco said about 4,500 to 4,600 COVID-19 beds in total will be occupied in Metro Manila.
“Apparently, despite those who called us alarmists, the Delta surge is worse than our projections predicted. Again, it looks like our model, while crude, is making some useful predictions, ”Austriaco said.
“I am grateful that the modelers at DOH FASSTER corroborated our findings that the Delta surge would overwhelm our hospitals. We are working together as Filipino scientists and modelers to serve our country against a common enemy, which is COVID-19, ”he added.
Austriaco pointed out that the models used by OCTA and DOH are both useful.
“Some have asked me if our model is better or worse than the DOH model. This is the wrong question to ask. Instead, we need to ask ourselves: Are our models useful? He stressed.
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