There is much we don't yet know about Covid-19. But there are some things we do know which could be used as part of the containment drive. Number one, we know it's highly contagious. Number two, we know people in frontline healthcare are more exposed to the virus than others in the population - among those who've contracted it, one in four is a health worker.
In Spain, the infection rate is 15pc frontline health workers and in Italy it is 9pc. This compares with 26pc in Ireland. So our infection rate for healthcare professionals is higher than any known rates in Europe, even in countries harder hit by Covid-19.
Our rate is also higher than the known rate for two previous epidemics, Sars and Mers, at 21pc and 18.6pc respectively. Healthcare infection rate is a known, measured entity and we have surpassed those norms.
Evidently, there is a greater than average potential that frontline health workers will develop Covid-19, even if they are careful and follow all the Health Service Executive (HSE) guidelines about protecting themselves and their patients - wearing a mask, maintaining social distance and monitoring their own symptoms if they come into contact with someone who has Covid-19.
How can we avoid putting these hardworking professionals at risk? And how can we mitigate the possibility of them inadvertently spreading the virus further among one another and the general population?
One possibility is regular, random sampling of frontline health workers. Currently, people are self-selecting for tests. But we know someone can transmit Covid-19 without showing any of the symptoms. The HSE is clear that staff should stop working and self-isolate for 14 days if they detect warning signs. But what about asymptomatic staff?
We're in the delay phase of the pandemic now, intended to reduce the burden on GPs and hospitals. (The stages are containment strategy, delay phase and mitigation strategy.) But stronger checks on frontline staff would be a useful instrument in delaying the spread.
Leaving the onus on individual health workers to volunteer for testing is illogical. There should be a procedure in place which takes it out of the individual's hands. Many medics are hard-wired to keep going, not least because they realise their absence would add to their colleagues' burden.
Is the reason we aren't testing partly because we fear the answer? Would it hammer hospital staffing levels?
Where frontline health workers test positive, there must be contact tracing of everyone they have interacted with, both inside and outside of work. Contact tracing is laborious but is certainty vital.
This week, Siptu called for regular screening of health workers for Covid-19. The trade union's health division organiser, Paul Bell, notes that where health workers have been infected, just under two-thirds of cases were unrelated to travel, meaning they contracted the virus in Ireland.
Elsewhere, sick leave among medical staff has more than doubled at Cavan General Hospital since January, with reinforcements being sent from Beaumont in Dublin to ease pressure. Some estimates suggest 70 doctors and nurses are off work. We don't know how many are out because of Covid-19 but it has to be a significant factor.
Pauline Tully, Sinn Féin TD for Cavan-Monaghan, told Shannonside Northern Sound she was contacted by hospital staff expressing concerns about protective equipment, showering and changing facilities. The hospital denies any problems in this regard.
Separately, Siptu has raised questions about the availability of personal protective equipment (PPE). The union says members are reporting it is not readily accessible in the quantities required and that people are resorting to re-using materials intended for single use.
In a statement to the Irish Independent, the HSE said it wasn't doing random testing but said it continues to prioritise tests for healthcare workers, as well as patients in acute hospitals and residential facilities.
Surely regular, random screening of all frontline healthcare workers is essential to ensure both their safety and ours? Not doing it undermines our attempts to deal with Covid-19. It can't be a case of one-and-done testing, either - this is a fast-moving virus and our highly valued health professionals will need to be sampled throughout the pandemic.
Ideally, random checks should be conducted among the population at large. We don't yet know how prevalent Covid-19 is in the population and reliable data is essential for policy-making.
But it makes sense to start with the sector most likely to contract Covid-19 because of the work its members are doing in this time of national emergency - still dedicated enough to turn up for work, although they know how difficult it is to care for people while maintaining scrupulous social distancing.
We are making strides in dealing with this pandemic but our slow pace of testing is a weakness. Some 51,000 people are still waiting for swabs; even when people get tested, the results can take too long to filter back. Our figures for how many people have Covid-19 are meaningless until testing is in real time and widespread.
In statistics, the larger the sample, the more confidence can be placed in the outcome. Limited testing limits the usefulness of results. Or, to put it another way, as sample size increases, margin of error reduces.
At present, people are volunteering to be tested, often because they suspect they have the virus, which potentially skews the outcome. Random screening would provide more reliable data. For example, if a random sample showed a high incidence of Covid-19 in certain institutions or wards, it would indicate the need for additional testing in those places.
Random testing helps to identify hubs of a virus and thereby inhibits its further spread. If one person in a team tested positive, other members of that group - and preferably all of them - would be sampled. This is standard scientific protocol.
Otherwise, there is a risk of someone being a 'super-spreader' and infecting dozens. The problem is we aren't spotting them. The super-spreader concept emerged in previous disease outbreaks such as Sars. While the World Health Organisation (WHO) doesn't use super-spreading as a technical term, it says there can be transmission "where a large number of people can become infected from a common source".
Breaking transmission chains is the most effective way to prevent contagion. "And to do that, we must test and isolate," says WHO director-general Tedros Adhanom. "You cannot fight a fire blindfolded. And we can't fight this pandemic if we don't know who is infected."
Some people believe random sampling to be a waste of time and resources, a diversion from areas where efforts should be directed. Scientists at Harvard and Stanford universities recommend it, however, and countries such as Germany are doing it.
Here, random sampling isn't within our current testing parameters, but arguably those parameters need to be extended. Right now, Ireland is at a crossroads - the wave hasn't hit us yet. Perhaps random testing of frontline healthcare workers might help us to move ahead of the curve.
It could save lives.
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