Recovered patients may not be immune to Covid-19: WHO

WHO warning comes as countries start to ease curbs, look into 'immunity passports'

Patients who recovered from the coronavirus wear protective clothing as they line up to be tested again at a hospital in Wuhan, on March 14, 2020.
Patients who recovered from the coronavirus wear protective clothing as they line up to be tested again at a hospital in Wuhan, on March 14, 2020.PHOTO: AFP

The World Health Organisation (WHO) warned yesterday that recovering from the disease Covid-19 may not protect people from reinfection as governments around the world start to ease restrictions to revive economies battered by weeks of closure.

While global Covid-19 deaths have climbed past 197,000, new reported cases appear to have levelled off at about 80,000 a day.

Italians are awaiting a decision this weekend about which of its restrictions will be lifted and they will probably be allowed to leave their homes freely for the first time since March 9 by early next month, reported Agence France-Presse.

Sri Lanka said it would lift a nationwide curfew tomorrow after more than five weeks, as Belgium joined other European nations to announce an easing from the middle of next month.

Singapore, where tightened circuit breaker measures will last till June 1, also had a respite with yesterday's announcement of 618 new cases, reflecting a general downward trend since the 1,426 new cases last Monday.

Most of yesterday's new cases - 597 to be exact - involved foreign workers living in dormitories.

The figure for new cases in the community was just nine. The average number for community cases also dipped to 23 per day in the past week, from 31 cases per day in the week before.

Even as some governments study measures such as "immunity passports" or documents for those who have recovered as one way to get people back to work, the WHO made clear it was a gamble.

"There is currently no evidence that people who have recovered from Covid-19 and have antibodies are protected from a second infection," WHO said. "People who assume that they are immune to a second infection because they have received a positive test result may ignore public health advice."

The spread of Covid-19 is increasing other medical risks as well, with the WHO warning that nearly 400,000 more people could die from malaria because of disruption to the supply of mosquito nets and medicines. Yesterday marked World Malaria Day, a disease which the WHO said could kill around 770,000 this year, or "twice as many as in 2018".

While the coronavirus daily death toll in Western countries seems to be falling, a sign hopeful epidemiologists had been looking for, the WHO also warned that other nations, especially the less developed ones, are still in the early stages of the fight.


Experts in Singapore have stressed that while the overall figures here appear to be moderating, they need to fall consistently for a few days before one can safely say that Singapore is on a surer footing in terms of containing the Covid-19 situation.

The country has a total of 12,693 cases, with 10,525 linked to foreign worker dormitories. This means about 3 per cent of the 323,000 foreign worker dorm residents here have caught the virus.

Dr Leong Hoe Nam, an infectious diseases expert who practises at Mount Elizabeth Novena Hospital, said that the new measures to stem the virus spread in dorms have paid off.

Since last Wednesday, foreign workers have not been allowed to leave their dormitories until May 4. The Government has also whittled down the number of essential services allowed to remain open.

Dr Leong said: "(The Government) has barred those in dorms from going to work. This prevents the workplace from being a mixing pot or transmission centre. With these measures, the numbers will come down."

Professor Paul Tambyah, president of the Asia-Pacific Society of Clinical Microbiology and Infection, said that it is a good sign that clusters outside the dorms, including work pass holders and Singaporeans, are being identified, such as one at Natureland East Coast spa that emerged on Friday.

"If more of the previously unlinked cases can be linked, then there is a good chance that we will be able to see a significant reduction in cases outside the dormitories and migrant worker accommodation," he said.

In a Facebook post on Thursday, Minister for National Development Lawrence Wong, who co-chairs the multi-ministry task force tackling the outbreak, said that Singapore's collective efforts are achieving results.

"But we must now give a further push to bring down the numbers more sharply," he said.

A version of this article appeared in the print edition of The Sunday Times on April 26, 2020, with the headline 'Recovered patients may not be immune to Covid-19'. Print Edition | Subscribe