The ministry of Health has cautioned Covid-19 testing facilities on the use of antigen rapid diagnostic kits (RDTs) to screen asymptomatic patients, saying they have a 50 per cent chance of returning false results.
According to the ministry, the RDTs should be limited to test persons who have symptoms of Covid-19 because these already have high viral loads of the disease that can easily be detected by the antigen RDTs. The ministry's warning comes at a time when many health facilities in the country have been using RDTs to carry out tests on all Covid-19 suspects including asymptomatic ones.
The tests have become popular due to their low pricing. RDT testing costs between Shs 60,000 and Shs 80,000 on the open market compared to the Shs 200,000 and more for a PCR test.
Prof. Pontiano Kaleebu, the director of the Uganda Virus Research Institute (UVRI) says the results of asymptomatic patients that use RDTS have a more than 50 per cent chance of being false. He says due to low viral loads of the disease, asymptomatic patients will likely get a negative result when they are actually positive, and thus lead to further transmission of the disease.
"These antigen kits are good when you have high viral load, if you have low viral load they give false negatives. Their sensitivity is not very good. So you miss out many who will appear negative when they have the virus and then they will continue spreading...They are widely used because even WHO and even the manufacturer say they are very good just before symptoms but that is when their viral load is high. But in the asymptomatic who don't have high viral load, some of them will turning out positive on the antigen but there will also be many who will turn out negative if they have a virus which they can spread," said Kaleebu.
Some of the common symptoms of Covid-19 in this second wave include headaches, sore throat, shortness of breath, loss of smell, diarrhea, runny nose among others. Kaleebu says people who present with two or more of these symptoms can use an RDT test.
Currently, the Panbio Covid-19 antigen test manufactured by Abbott Pharmaceuticals and the Standard Q test manufactured in South Korea are currently being used in Uganda. The sensitivity of the RDTs is 50 per cent compared to the PCR one that stands at over 80 per cent according to Prof Kaleebu.
According to Kaleebu, persons with symptoms that test positive with RDT tests even will likely test positive with a PCR test, but asymptomatic negative patients will turn out to be positive. To increase the Covid-19 testing capacity, the health ministry has distributed antigen RDTs country-wide.
Minister of Health Dr Ruth Aceng says the kits will enable easier and faster screening of possible Covid-19 infections. She says the testing is free of charge at all government facilities.
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