WHO official clarifies position on asymptomatic COVID-19 spread

Matt Woodley

10/06/2020 4:17:10 PM

The global health body’s COVID-19 technical lead concedes ‘we don’t actually have that answer yet’.

Dr Maria Van Kerkhove
The WHO’s Dr Maria Van Kerkhove said the response to her comments was the result of a ‘misunderstanding’. (Image: AAP)

The head of the World Health Organization’s (WHO) emerging diseases and zoonosis unit, Dr Maria Van Kerkhove, has had to clarify her widely publicised claims that asymptomatic spread is ‘very rare’.
At a specially arranged press conference, Dr Van Kerkhove said that, in fact, ‘we don’t actually have that answer yet’.
Dr Van Kerkhove’s original comments generated confusion as they contradicted studies and modelling that indicate asymptomatic transfer could be much higher than previously assumed, as well as the WHO’s recent shift in position on wearing masks in public.
She was also criticised for not differentiating between pre-symptomatic and asymptomatic cases, due to the potential for media organisations to erroneously interpret her statement as referring to all symptomless cases.
Research has shown viral shedding occurs in pre-symptomatic cases, with infectiousness likely peaking on or before symptom onset.
In clarifying her comments, Dr Van Kerkhove described the situation as a ‘misunderstanding’ that came about when she answered a journalist’s question about the specific role asymptomatic transfer has in spreading the virus.
‘I used the phrase “very rare” and I think that it’s a misunderstanding to state the asymptomatic transmission globally is very rare … we don’t actually have that answer yet,’ she said.
‘I wasn’t stating a policy of WHO or anything like that … what I was referring to was a subset of studies. These are estimates, and there’s a big range from the different models.
‘Some estimates of around 40% of transmission may be due to asymptomatic, but those are from models and so I didn’t include that in my answer yesterday.
‘We do know that some people who are asymptomatic, or some people who do not have symptoms, can transmit the virus on.’
A recent review analysing data from nine international studies, led by Australian general practice researcher Professor Paul Glasziou, suggests asymptomatic coronavirus cases account for around 15% of COVID-19 infection, but that these people spread the disease at a ‘considerably lower rate’.
Another study, published on 9 June by the US Centers for Disease Control and Prevention (CDC) and based on the USS Theodore Roosevelt outbreak, found one fifth of infected participants reported no symptoms.
It also found preventive measures, such as using face coverings and observing social distancing, reduced the risk of infection.
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