Case study of cancer patient suggests those with COVID-19 can be infectious for up to 70 days despite being asymptomatic
When a virus enters your body and causes infection, it makes you infectious. During this infectious stage, your body sheds the virus at a high rate and this increases the risk of transmitting the virus to others
When a virus enters your body and causes infection, it makes you infectious. During this infectious stage, your body sheds the virus at a high rate and this increases the risk of transmitting the virus to others. This stage is known as the viral shedding stage and all precautions must be taken with the utmost care at this point.
Viral shedding of infectious SARS-CoV-2
Given the widespread awareness about the current COVID-19 pandemic, the concept of viral shedding, including its risks and precautions, has become better known. The presence of SARS-CoV-2 and its infectiousness can be tested by checking the viral ribonucleic acid (RNA) from samples collected from a patient’s nasopharyngeal tracts, blood or stool.
Current estimates suggest that SARS-CoV-2 infectiousness begins 2.3 days prior to symptom onset and declines within seven days of symptom onset.
Even in asymptomatic patients, the viral load decreases after eight days at most, according to studies. In fact, the longest detected case of viral shedding of infectious SARS-CoV-2 was recorded by a preprint study in June 2020, which said a patient had been infectious for 20 days. However, a new study published in the journal Cell suggests that the viral shedding stage can be abnormally long based on a single case they observed in the state of Washington, US.
The curious case of a leukemia patient
The case study notes how a 71-year-old woman with a 10-year history of chronic lymphocytic leukemia, acquired hypogammaglobulinemia, anemia and chronic leukocytosis came to an emergency ward with low back and leg pain on 12 February. She underwent surgery for spinal fracture and stenosis due to her cancer two days later and was then transferred to a rehabilitation facility on 19 February. She was rehospitalised due to anemia on 25 February at a different rehabilitation centre since the previous one had reported a COVID-19 outbreak.
Although she had no symptoms at all, the patient was tested for COVID-19 since she had stayed at the rehabilitation centre at the time of the outbreak. She tested positive for COVID-19 on 2 March and was kept in isolation. Over the next 15 weeks, she was tested for SARS-CoV-2 another 14 times by several diagnostic companies and remained positive until 15 June, 105 days since her first positive result. Subsequently, the patient tested negative through four consecutive swabs from 16 June to 16 July, finally indicating that she was infection-free.
105 days with COVID
The researchers found that of the 105 days, the patient had remained infectious for 70 days. This prolonged viral shedding stage, they believe, was owed to the fact that the patient was severely immunocompromised due to her cancer and other morbidities. The blood tests conducted frequently on the patient show that her body was never able to make the antibodies to clear the infection out, even though at one point she was also treated with convalescent plasma therapy.
The scientists even checked her blood to examine if virus mutations were responsible for her prolonged disease. They found that although there were mutations, no single gene variant was dominating over the others, and hence genetic mutations in the SARS-CoV-2 virus could not be held responsible for causing this patient’s prolonged COVID-19 infection. Her immunocompromised state was identified as the single determining factor.
Another point to note is that despite creating no antibodies against COVID-19 , the patient never developed severe COVID-19 or even a single symptom associated with the disease. She remained asymptomatic throughout the 105 days of her infection. The researchers believe that though this was reportedly the longest case of COVID-19 infection yet, they expect more such findings to emerge given that the pandemic is anything but over and such long-term viral shedding cases have previously been noted during the Middle East respiratory syndrome (MERS) and influenza outbreaks.
For more information, read our article on Viral load.
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