A variant of SARS-CoV-2 with a D614G substitution in the gene encoding the spike protein emerged in late January or early February 2020. Over a period of several months, the D614G mutation replaced the initial SARS-CoV-2 strain identified in China and by June 2020 became the dominant form of the virus circulating globally.
The standard method of testing for presence of SARS-CoV-2 is real-time reverse transcription polymerase chain reaction (rRT-PCR), which detects the presence of viral RNA fragments. As this test detects RNA but not infectious virus, its “ability to determine duration of infectivity of patients is limited.” The test is typically done on respiratory samples obtained by a nasopharyngeal swab; however, a nasal swab or sputum sample may also be used. Results are generally available within a few hours to two days. Blood tests can be used, but these require two blood samples taken two weeks apart, and the results have little immediate value.
The most common symptoms of COVID-19 are:
- Dry cough
- Loss of taste or smell,
- Nasal congestion,
- Conjunctivitis (also known as red eyes)
- Sore throat,
- Muscle or joint pain,
- Different types of skin rash
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