The change shows up as a small uptick on the graph of daily case numbers, but after two months of mostly steady decline it was sufficient to cast an air of gloom over Thursday’s National Public Health Emergency Team (Nphet) briefing.
"We are sailing very close to the wind," said Nphet's modelling expert Prof Philip Nolan. "A gust of wind in the wrong direction and we're in real trouble."
Was the increase in cases this week really evidence of the beginning of another wave of Covid-19?
Or was it a blip seized upon in order to put the frighteners on people and shore up declining compliance with public health advice?
Time will tell.
The wider issue is why Ireland is stuck at about 500 cases every day, months into a third lockdown and despite the rollout of vaccines. Progress on case number has been slowing for weeks now, and the reproduction number, the number of infections linked to each confirmed case, is hovering just below 1.
Have all our sacrifices been in vain? Are we not doing things right? Will it mean further delay in easing restrictions or even the imposition of new ones? These are inevitable questions for an increasingly frustrated public.
Nphet explains our current impasse by pointing to the more transmissible, and now dominant, B117 strain first identified in the UK. Without B117, Ireland would be down to about 20 cases a day, according to some experts.
Mingling
Instead of that, any increase in mingling in the population is “rewarded” with more new cases, many more than would have been the case last year when the variant was not present. It may also give rise to more serious illness than was the case with other variants. Other countries have seen cases rise as B117 makes inroads.
Nphet has focused on mobility, as measured by Google tracking of our household and workplace movements, as an extra factor behind the increase in cases.
There is also data on where people use their phone, or withdraw money from ATMs, but none of this information tells anything about whether people are observing social distancing or isolation rules, for example.
It takes infected people to pass on this disease. The Nphet view tells us little about where the new cases are arising. Though 900 people are now working in contact tracing, only sparse information emerges about outbreak patterns.
A few weeks ago, it took the media to highlight large student clusters in Galway and Limerick; this week, the only specific references by Nphet was to outbreaks in workplaces and among Travellers.
The public health doctors employed to track disease tell a different story; of a lack of resources; of having to rely on pen and paper and basic Excel spreadsheets; of outdated computer systems that don’t talk to each other.
"There are almost no supports put into investigating the chains of transmission" of the disease, public health doctor Dr Ina Kelly told RTÉ's PrimeTime this week.
Another says: “We’re no better equipped than a year ago”.
A month ago, Nphet said one-quarter of cases were not being followed up to establish the source of infection. The situation seems not to have improved since.
Blunt instrument
Could this be the reason for relying on the blunt instrument of lockdown for so long? Currently, 10 counties appear to have effectively suppressed the virus, with average daily case numbers in single figures, yet they are treated the same as other parts of the country with big outbreaks.
Meanwhile, vaccination is changing the calculus of lockdown, rapidly and massively. Cases have fallen off a cliff in healthcare settings and in nursing homes after staff, patients and residents were inoculated. Deaths are declining, too, as the most vulnerable groups are protected.
Israel’s experience shows you can still have active transmission even when most of the population is immunised. But the capacity for harm is greatly reduced, so the rationale for severe restrictions is greatly weakened.
Ireland hasn’t reached that point yet, of course, though the way our vaccination programme has been targeted at specific vulnerable groups means they should soon be able to enjoy a wider “vaccine bonus” than is currently proposed.
The rest of us can only wait, watch the stop-and-go nature of the vaccine rollout and wonder when we will be able to buy children’s shoes again.