Sri Lanka needs to consider the false negatives, strengthen public preventive measures and ramp-up testing
How should the country move into the ‘new normal’ future, essentially living with COVID-19? A dengue expert, who along with a few others changed the management of that mosquito-borne viral disease in Sri Lanka, has come up with some relevant suggestions.
In an interview with the Sunday Times, the Clinical Head of the Centre for Clinical Management of Dengue & Dengue Haemorrhagic Fever, Negombo & Consultant Paediatrician, Dr. LakKumar Fernando, discussed some “newer” thoughts about the new coronavirus: the exit strategy vs living with COVID-19.
Before focusing on Sri Lanka, Dr. Fernando glances at other countries, while reiterating that COVID-19 being a new disease, the world is on a “big” learning curve. This means that strategies need to be changed based on new information, he says.
When Singapore had 8,000 tested positive cases, there were only 11 deaths. When China had 80,000 cases and 4,000+ deaths, its case number may have been 8 million, as it did not do extensive testing those days. Italy's testing was very low and its death rate was shown as 10%. Germany, however, with more testing ended up with a 0.4% death rate.
At that time, Sri Lanka had 250 cases and 7 deaths. It did not mean Sri Lanka was 20 times worse than Singapore in treating patients. If at all, Singapore may be twice better than Sri Lanka. If Sri Lanka had 7 deaths, maybe our corresponding case number was 3,0005,000. If many people have recovered, maybe Sri Lanka has 2,000-3,000 active cases now. community spread has begun. The example he cites is a location like the highly-congested Bandaranayake Mawatha in Gunasinghepura.
Has the community spread of COVID-19 begun in Sri Lanka?
This is his analysis:
If such a location has 2,000 people, all were tested for COVID- 19 through RT- PCR ( Reverse Transcription- Polymerase Chain Reaction) and there were 60 ‘positives’, the chances are that there could also have been 40 ‘false negatives’.
This is because when nasopharyngeal samples are taken for the RT-PCR test, the virus would be found within the samples only in about 60% of the cases, when it is done by trained staff in a laboratory setting. However, these samples are not being taken under ideal conditions. As such the ‘false negativity’ could be even higher than 40%.
The next step is to admit the 60 ‘positive’ people to hospital and carry out contact tracing of all those who associated with these patients. The balance 1,940 people, who are in quarantine would be released back to the community after 14 days, under the assumption that they would develop symptoms if they have the virus within those 14 days.
But current data show that more than 95% will be largely asymptomatic or mildly symptomatic. This means that when they are released to the community, at least 40-50 among them could continue to spread the disease even without symptoms.
The two solutions for this are:
The affordable solution is to be realistic and tell the people that there could be a number of asymptomatic people around them who could spread the disease and minimize spread by installing very serious precautionary measures.
Finding ways to correctly identify the ‘false negatives’ and do contact tracing for them as well. These could be by ramping up testing. In a low-resource setting like Sri Lanka, in addition to RT- PCR testing, the place for other options should be properly evaluated.
These options which should be evaluated are the newly- emerging rapid antigen testing (to save time and cost) and using sensitive antibody testing after 14 days. The antibody test would be to identify the extent of infection-spread in the community.