In the past few weeks, a lot of people have been looking at the IHP estimates of required PCR testing capacity that I posted back in early April. We have not had the resources to revise these yet,* but if you are using our April estimates, this is to alert you that they are no longer valid.
In April we estimated that average daily PCR testing should be 6,000 tests/day, and that national PCR capacity should be 9,000 tests/day. Our daily testing need right now is probably in the range of 40-50,000 tests/day.
These are some of the reasons:
1. Contact tracing requirement has increased
We assumed that testing would be increased as proposed, and that as a consequence routine new case detections would be kept at below 5/day, and that any new outbreak would be kept at below 50 cases/day The testing increase did not happen. We now have 500+ new cases/day and there is a strong possibility that these numbers under-estimate actual incidence because our case detection is limited by our PCR testing capacity. If we assume that actual new cases are running at 1,000/day, we currently need 20,000 tests/day to cover contact tracing requirements.
2. Requirement for clinical management of COVID-19 cases has increased
We assumed that there would be a maximum of 50 new cases/day requiring 125 tests/day for clinical management. With 1,000 cases/day, this number increases to 2,500 PCR tests/day.
3. We have a better understanding now of how much routine community testing is needed to prevent new waves
In April, based on what China was saying and the experience of other poor Asian countries, we concluded that high levels of routine symptomatic testing of people in the community was needed to prevent outbreaks. We now have much better evidence on that. This indicates that higher levels of routine testing than we originally thought are needed to prevent second waves, especially if we keep our airports open. These levels are much higher than what the WHO is recommending globally. Extrapolating from other research and the experience of say New South Wales (Australia), which has kept its schools and airport open, avoided lockdown and kept monthly cases of community transmission in the single digits. we probably need to be doing 20,000 tests/day on people with respiratory symptoms (coughs and colds) or fever.
My best guess is that we currently need 40,000 PCR tests/day, and we should be looking at increasing long-term national capacity to 50-60,000 tests/day, assuming we get over the current outbreak.
 During the past six months, the WHO has suggested various testing levels as being adequate, ranging from 1 test per 1,000 people each week to 30 tests for every positive case detection. These translate into rates of 3–15,000 tests/day in Sri Lanka currently. Our assessment is that these guidelines do not have a strong evidence base, and that these levels of testing are too low to achieve and maintain elimination, which needs to be our goal if we are to avoid lockdowns as desired by our President.
*IHP’s work on COVID-19 is not funded and we don’t slant our recommendations to suit our sponsors. Our team is doing all this on a pro-bono basis to provide the country with unbiased, evidence-based analysis. If you want to help us or support us to keep up this work, please contact us at [email protected].
2020/11/09: Updated with edits plus note on WHO recommended testing levels