It's too early to credit curfew for drop in COVID infections: health experts
Health authorities in Quebec have reported fewer than 2,000 new cases of COVID-19 for four consecutive days — almost two weeks since the imposition of a provincewide curfew between 8 p.m. and 5 a.m.
Premier François Legault has suggested the drop in cases might be the result of the curfew, which he said he imposed to reduce COVID-19 transmission, especially for people older than 60. The measure will be in effect, he said, until at least Feb. 8.
Health experts say it's too early to know for certain whether the curfew is behind the significant drop in new daily cases. But they differ on whether the drastic measure should start getting some credit.
Benoît Mâsse, professor of public health at Université de Montréal, said it's “very difficult to know” whether the curfew is working because that measure was one of several restrictions imposed to reduce spread.
Quebecers also got a “rude awakening,” Mâsse said, when earlier this month officials reported more than 3,100 cases in a single day, sparking public warnings from doctors who said hospitals were on the verge of rationing care.
Those warnings may have shocked Quebecers into reducing their contacts, Mâsse said in an interview Wednesday. But, he added, the curfew may have also played a role in shocking Quebecers into staying home.
Roxane Borgès Da Silva, a public health professor at Université de Montréal who was one of the experts calling for a curfew in early January, said the measure might be having the desired effect.
She said a new study by researchers at the Aix-marseille University in France indicates that a partial lockdown coupled with a curfew reduced transmission in that country among people aged 20 to 60.
That study, An Early Assessment of Curfew and Second COVID-19 Lock-down on Virus Propagation in France, which has not yet been peer reviewed, found that the acceleration of viral spread among people older than 60 “decreased notably with curfew measures.”
On Wednesday, the Health Department reported 1,502 new cases of COVID -19 (629 in Montreal) and an average of 1,792 cases over the previous seven days, down from an average of 2,385 the week before.
Dr. Matthew Oughton, an infectious disease specialist at the Jewish General Hospital, said it's difficult to define the impact of individual measures when many are in force at the same time.
“Is curfew the only reasonable explanation for the reduction? Probably not,” Oughton said in an interview, adding that he believes the extended school winter break also contributed to the reduction in cases.
“Now that (schools) opened up again, we may be seeing these numbers start to rise again within the next week or so. This wouldn't be the first time that we've had these sort of ups and downs during the (second) wave.”
Mâsse also said it's too early to say whether the trend will continue. Quebecers should wait, he added, before they declare victory.
Quebec's high test positivity rate may also suggest there are more cases in the province than recent reporting periods suggest, Oughton said. “There's lots of reasons to believe that our numbers are not fully capturing the extent of community transmission.”
A test positivity rate above five per cent is the signal for undetected — and uncontrolled — community transmission, he said. As of Monday, the test positivity rate across the province was six per cent, according to Quebec's national public health institute. It was above 10 per cent in Montreal on Sunday.
The number of tests conducted in Quebec has also dropped recently.
Over the past month, Quebec has conducted an average of more than 30,000 tests a day, according to public health data.
On Monday, however, the most recent date for which testing data is available, the province conducted 28,889 tests. On Sunday, 20,412 tests were conducted — the lowest number of tests administered in a single day in the province since Dec. 26.
The Health Department did not respond to a request for comment on Wednesday afternoon. Oughton, however, said the number of tests conducted generally drops during the weekend.
The Health Department reported 66 more deaths attributed to the novel coronavirus Wednesday (17 in Montreal), including 10 that occurred in the preceding 24 hours. Health officials said hospitalizations dropped by 33, to 1,467, and 216 people were in intensive care, an increase of four.
Quebec has reported 247,236 COVID-19 infections and 9,208 deaths linked to the virus since the start of the pandemic.