Jessi Kristin Martha Juliana Ropa Pengarang SEBASTIANUS ADI SANTOSO MOLA Dosen Pembimbing 1 MEITON BORU Dosen Pembimbing 2 Sebastianus Adi Santoso Mola Ketua Penguji Derwin Rony Sina Penguji 2 Meiton Boru Penguji 1

Coronavirus Disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus that attacks and infects the respiratory tract. The general symptoms of COVID-19 have similarities with several diseases such as influenza and pneumonia that are difficult to distinguish by nonexperts. Therefore, to overcome this, an expert system is needed to diagnose COVID-19 early by implementing forward chaining methods and certainty factors based on the symptoms experienced. The expert system will diagnose COVID-19 by classifying it into two categories of patients, namely ODP and PDP. The results of the diagnosis can be used as an early reference before going to the doctor for further examination. Based on the research conducted, it was found that the results of the forward chaining and certainty factor methods were proven to be able to be applied with a system accuracy level for early diagnosis of COVID-19 of 90.56%.