That’s the surprising claim, first made on Twitter and later shared widely elsewhere, including several times on Facebook, in early July 2020.
The message refers to people infected with the novel coronavirus, which causes Covid-19. It ends with the hashtag #coronascam.
Twitter deleted the original tweet because it “violated the Twitter Rules”.
The WHO advises that people who test positive for Covid-19 should be isolated or quarantined to stop the disease from spreading to others.
Has the organisation now withdrawn this advice and said Covid-19 “cannot even transmit from one patient to another”, as the message claims? We checked.
Quarantine, isolation still important
The original tweet included a video clip from a longer Newsmax TV segment.
Newsmax is a US cable news channel, considered politically conservative and favoured by US president Donald Trump.
The segment showed anchor Greg Kelly and Newsmax contributor Dr David Samadi discussing a WHO media briefing on 8 June.
The two examined the implications of a comment made by Dr Maria van Kerkhove, Covid-19 technical lead for the WHO Health Emergencies Programme.
Van Kerkhove said: “From the data we have, it still appears to be rare that an asymptomatic person actually transmits [Covid-19] onward.” She was talking about asymptomatic Covid-19 cases, where infected patients don’t show signs of the disease.
She did not say the coronavirus “cannot even transmit from one patient to another”.
Van Kerkhove and other experts at the press conference did not suggest that positive cases did not need to be isolated or quarantined. In part this is because symptomatic patients, who do show signs of Covid-19, can still spread the disease.
“If we followed all of the symptomatic cases, isolated those cases, followed the contacts and quarantined those contacts … it would be a drastic reduction in transmission,” Van Kerkhoven said a few moments before the segment shown on Newsmax.
The social media posts are incorrect. The WHO has not said that isolating and quarantining Covid-19 cases is unnecessary, nor has it said that the disease cannot be transmitted by those who have it.
But could this be true of asymptomatic cases?
Asymptomatic transmission also possible
In the Newsmax clip, Kelly and Samadi say “asymptomatic people are not infectious” and cannot transmit Covid-19.
But Van Kerkhove did not say that asymptomatic transmission is impossible, only “rare”, and the WHO has been clear that this type of transmission is still worrying.
A Reuters reporter asked Van Kerkhove about asymptomatic transmission, as the WHO had previously said it had seen no evidence of it.
Van Kerkhove clarified her comments on 9 June, the day after the WHO press briefing. She said: “I think that it’s a misunderstanding to state the asymptomatic transmission globally is very rare.”
She acknowledged that cases of asymptomatic transmission had been recorded, and that despite her comments the previous day some models estimated up to 40% of Covid-19 cases could have been transmitted by people with no symptoms.
Van Kerkhove also pointed to another important distinction, between asymptomatic and “pre-symptomatic” cases – patients who would develop full symptoms but appeared not to for some time.
Asymptomatic or pre-symptomatic? Both contagious
The WHO said in April that people with Covid-19 could be contagious during the pre-symptomatic stage of the disease, which lasts up to 14 days.
Some patients without symptoms may be pre-symptomatic, not asymptomatic, and unquestionably able to transmit the disease.
Many questions about asymptomatic transmission remain unanswered. It’s discussed in the literature review Unclear Issues Regarding Covid-19, published shortly after the WHO press briefing.
The review says it is still unclear how likely asymptomatic cases are to be contagious or for how long.
But what is clear is that asymptomatic and pre-symptomatic cases are contagious. All Covid-19 patients, even asymptomatic ones, should isolate or quarantine. – Keegan Leech
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