An enhanced testing and tracing system for Covid-19 is to be introduced on Wednesday which is expected to halve the number of cases where health officials cannot identify where a person has been infected.
Currently, 80 per cent of cases of Covid-19 are traced to a specific source through the Health Service Executive’s contact tracing centres or through HSE public health teams. The remaining 20 per cent are classified as cases of community transmission.
Public health officials often reclassify these cases when they have the opportunity to contact the individual again. This frequently reduces the 20 per cent community transmission figure downwards, and the new uniform approach is expected to bring community transmission down to 8-10 per cent.
As of Wednesday, contact tracers will ask people with Covid-19 who are classified as cases of community transmission extra questions about events or places they were at in the seven days before their symptoms began. Up to now, contact tracing calls have in most cases only traced activity for the 48-hour period prior to a positive test result.
If the confirmed case did not have symptoms, contact tracers will ask about events or places they were at the week before the day of their Covid-19 test.
The HSE said conducting this activity as standard procedure aims to identify where transmission may have occurred in more cases. This will provide real-time information about events and situations of where the virus is spreading.
Public health teams may then decide to offer testing to people that were at the same venue or setting at the same time as the confirmed case, to stop further spread of disease and prevent clusters of Covid-19 developing in the community.
Asymptomatic cases
HSE clinical lead for contact management programme Dr Greg Martin said the exercise will identify contacts who may be asymptomatic.
“They will then be offered a test and that will be a mechanism where we will identify additional cases, and where we identify additional cases there is an opportunity to interrupt transmission,” he said.
“At the point in time where people are identified as having been in a setting that we’re investigating, they will be offered a test, but they won’t at that point be asked to restrict their movements per se, because at that point we don’t know really if they were a close contact or not.
“At that point in time, we are just looking at that setting. We don’t have any firm information or data to suggest that was necessarily the setting in which there was transmission. But as soon as we know that these people were in fact exposed, they will be given the appropriate public health advice.”
Dr Martin said the approach is most effective when case numbers are low. “So, as this pandemic eventually simmers down and the vaccine programme takes effect and we see the numbers really coming down, this kind of contact tracing becomes increasingly effective,” he said.
“We believe it will be effective even at the levels we have at the moment, but are absolutely sure that as the numbers go down, this kind of chasing every last case is going to be an important part of the endgame of our public health response to this pandemic.”
However, the system has “almost no value” in a scenario where numbers are at “extremely high levels”, according to Dr Martin. “It is something we will preserve the opportunity to turn on and off depending what is most appropriate at a given time.”
There are 825 staff in the contact tracing programme, but there are no plans to take on extra staff to deal with the additional workload.
HSE national lead for testing and tracing Niamh O‘Beirne said it would involve an additional six or seven minutes on the phone in the 20 per cent of positive cases that are classified as community transmission. “It’s well within the capacity of the contact tracing system to pick that up,” she said.
