Covid: More Wales restrictions 'inevitable' if cases rise
Giri Shankar, Public Health Wales' outbreak response director, said the firebreak lockdown achieved its purpose of halting the rapid growth of cases.
But he said it was not yet known if the action has been enough.
Case data over the next two weeks would indicate if the current downward trend of cases would continue, he added.
"What remains to be seen is whether the reduction is sufficient enough, whether we can sustain it for enough to be able to manage the essential services," Dr Shankar said.
He emphasised this depended on "individual and collective responsibility" in following the national guidelines which came into effect on 9 November and ran for 17 days.
"If there is an uncontrolled spread of the virus and if there is a further increase in cases and that leads to inevitably higher hospitalisations and a proportion of those translate to deaths then it is inevitable at some point that we will have to consider further additional restrictions," he added.
He said any further restrictions were ultimately the Welsh Government's decision.
His warning comes on the day Merthyr Tydfil became the first part of Wales where a mass testing scheme will be rolled out.
NHS Wales chief executive Dr Andrew Goodall said Merthyr Tydfil was an "obvious choice" for mass testing, given the recent high level of Covid-19 infections in the area.
Dr Goodall said the Welsh Government was "appealing to the population" in the county "to support us in this initiative to undertake that more repeated testing, whether they have symptoms or not".