Most Covid-19 patients not infectious after 11 days: Study

Time in hospital, resources can be cut if MOH incorporates findings into discharge criteria

Singapore now discharges patients only after two swab tests are negative for the virus. ST PHOTO: KEVIN LIM

Health officials here are looking into a local study which suggests that more than 80 per cent of Covid-19 patients can be discharged after as early as 11 days, instead of having to test negative twice for the virus, as is the current practice.

Experts believe the findings can significantly cut down the time patients spend in hospitals and care facilities, and the resources needed to take care of them.

But the decision on whether to change the discharge criteria has to come from the Ministry of Health (MOH), which was informed of the study some days ago.

The position paper, released yesterday by the National Centre for Infectious Diseases (NCID) and the Academy of Medicine's Chapter of Infectious Disease Physicians, was based on a multi-centre study of 73 patients here.

It concluded that after 11 days of getting sick, most patients no longer pose a risk of spreading the disease despite continuing to test positive for the virus. This means they can be safely discharged.

The study showed that the positive tests "did not equate to infectiousness" as what they are detecting may be fragments of the virus or a non-viable virus - both of which cannot infect anyone.

The academy chapter involved in the paper represents more than a third of Singapore's 87 infectious diseases doctors from the public and private sectors.

NCID executive director Leo Yee Sin said: "Scientifically, I'm very confident that there is enough evidence that the person is no longer infectious after 11 days."

The only exceptions are patients with weakened immune systems, such as cancer patients receiving chemotherapy or people on immunosuppressant drugs following a transplant. The virus in them might remain viable for a longer period.

Dr Asok Kurup, who chairs the chapter in the academy, is equally confident about the results. The infectious diseases expert in private practice said: "Studies are still going on and we will get more data, but we will see the same thing as there is a great deal of science in this. So there is no need to wait."

The paper also refers to a "small but important study" in Germany of nine patients which found viral shedding from the throat and lung to be very high in the first week. But there was no more shedding by Day 8.

When asked why it took three days longer in Singapore, Prof Leo said the researchers here were "very conservative and counted till the very last drop".

Currently, the time when Covid-19 patients in Singapore are discharged is determined by negative results in two tests administered 24 hours apart.

Recently, 18 patients who had mild symptoms were released after spending between 38 and 51 days in a care facility, despite continuing to test positive. MOH said they were shedding "dead viral components", which, though detectable in testing, were inactive. They had to quarantine themselves for seven days after their release.

When asked about the new study, MOH said it "will closely study the position statement and evaluate how we can incorporate the latest evidence... into our patient clinical management plan".

It added that its management of Covid-19 patients is guided by the latest local and international clinical and scientific evidence.

The researchers plan to publish the results in an international journal of repute.

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A version of this article appeared in the print edition of The Sunday Times on May 24, 2020, with the headline Most Covid-19 patients not infectious after 11 days: Study. Subscribe