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The National Public Health Emergency Team is dead, long live Nphet. The group which steered the country through the coronavirus pandemic over the past two years is to be replaced by a 20-person Covid Advisory Group (CAG).
The Department of Health says the new group will monitor the Covid-19 situation, as well as emerging evidence regarding technologies, practices and interventions. It will also advise the Government on responses that might be necessary to respond to the threat of the virus.
As well as being a slimmed-down entity, inevitably there are new names who did not feature in Nphet Mark 1. Perhaps the most significant is the addition of UCC professor of physical chemistry John Wenger.
An expert on the role of ventilation in reducing transmission of Covid-19, his nomination to the new group acknowledges a concern that the role of airborne transmission of the Sars-CoV-2 virus may not have been fully addressed.
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It wasn't until October 20th, 2020, that the WHO acknowledged that aerosols – tiny specks of fluid – can transmit the virus
The blind spot about the full significance of airborne virus transmission was a global one. The World Health Organisation (WHO) resisted acknowledging an equal role for airborne transmission and aerosol transmission. Early in the pandemic, it tweeted: "FACT: #COVID19 is NOT airborne." At that time, the UN agency maintained that the virus spread mainly by droplets produced when a person coughs, sneezes or speaks. This reflected long-established infection-control teaching about how respiratory viruses generally pass from one person to another.
It wasn’t until October 20th, 2020, that the WHO acknowledged that aerosols – tiny specks of fluid – can transmit the virus, but even then it said this was a concern only in specific settings. Over the following six months, the agency gradually altered its advice to say that aerosols could carry the virus for more than a metre and remain in the air.
The WHO’s acknowledgement places the Sars-CoV-2 virus among a select group of airborne infections, including measles, chickenpox and tuberculosis.
According to the journal Nature, the WHO’s reluctance to accept and communicate evidence for airborne transmission was based on a series of problematic assumptions about how respiratory viruses spread. Critics say that inaction at the agency led to national and local health agencies around the world being similarly sluggish in addressing the airborne threat.
There appears to have been a significant disconnect between physicians and physicists. Infection-control experts have long drawn a hard line between droplet viruses and airborne ones, seeing only the latter as capable of travelling far and lingering in the air.
Superspreader events
Prof Trish Greenhalgh, professor of primary care research at the University of Oxford, says that, in effect, the WHO expert group failed to look at the whole picture that was emerging. "You've got to explain all the data, not just the data that you've picked to support your view." She cites the propensity for the virus to transmit in "superspreader events", noting: "Nothing explains some of these superspreader events except aerosol spread."
The downplaying of droplet spread has had the knock-on effect of muddying the role of ventilation as a control measure for the spread of Covid
Even now, questions remain about how much of COVID-19 transmission is airborne. But the downplaying of droplet spread has had the knock-on effect of muddying the role of ventilation as a control measure for the spread of Covid.
This confusion led Prof Wenger, the then chairman of an expert group set up specifically to advise the Government on the role ventilation could play in combating the spread of Covid-19, to express frustration with Minister for Health Stephen Donnelly in December.
The Minister had repeatedly said that open windows and C02 monitors provide “sufficient” ventilation in schools. This was despite a report by Wenger’s group recommending the use of Hepa (high efficiency particulate air) filters in poorly ventilated areas.
Now that he is a full member of the new CAG, let’s hope Prof Wenger’s expertise is incorporated fully into its deliberations. A greater role for ventilation in the suite of Covid-19 preventive measures could be crucial come the autumn.