Coronavirus immunity can last up to 8 months

Coronavirus immunity could last for years, according to new study

According to the researchers, majority of viral transmission events occur very early, and especially within the first five days after symptom onset, indicating the importance of self-isolation immediately after symptoms start.

People are most likely to pass on coronavirus within the first five days of having symptoms, an extensive study suggests.

Lead author Dr Muge Cevik, of the University of St Andrews, said: 'This is the first systematic review and meta-analysis that has comprehensively examined and compared viral load and shedding for... three human coronaviruses'.

Genetic material of Sars-CoV-2, the virus that causes COVID-19, may still be detected in the respiratory or stool samples of sufferers for several weeks, but no livevirus was found in any type of sample collected beyond nine days of symptoms starting, the research found.

However, in a striking piece of information which throws new light at the situation, a team of researchers from Howard Hughes Medical Institute, Rockefeller University, New York, have found that rather than depleting entirely, the virus-fighting antibodies become more potent and capable of fighting any mutations and virulent strains of SARS-COV-2.

The researchers further said there's a need to raise public awareness about the range of symptoms linked with the disease, including mild symptoms that may occur early on in the course of the infection than those that are more prominent like cough or fever.

Meanwhile, inactive viral RNA fragments were still found in nose and throat samples on average up to 17 days after symptoms started.

The reason, researchers say, is because the viral load in patients with COVID-19 appears to peak in the upper respiratory tract between day one of symptoms and day five of symptoms. They said the results are only relevant for the period of self-isolation for people with confirmed COVID-19, and do not apply to people quarantining who may or may not have been exposed after contact with someone infected. However, most studies indicated that patients without symptoms still have two key advantages: they may be able to clear the virus faster from their body, and they could be infectious for a briefer period of time. "Duration of infectiousness and subsequent isolation timelines could reflect viral load dynamics and could be counted from symptom onset for 10 days in non-severe cases", they added.

In the United Kingdom, officials say people must isolate immediately and for at least 10 days if they have any symptoms of coronavirus. "However, at this stage, there are limited data available on the shedding of infectious virus in asymptomatic individuals to inform any policy change on quarantine duration in the absence of testing", Cevik said.

Scientists had feared that those who developed only mild infections would be unlikely to have a strong immune response, but nearly all developed cells capable of creating new antibodies if they encountered the virus again.

The US-wide study looked at 817 older patients who tested positive for the coronavirus, 226 (28 per cent) of whom were diagnosed with delirium.

The new research reinforces previous studies that used contact tracing and determined spread happened fastest at the onset of infection.



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