As Nova Scotia lifts all remaining COVID-19 restrictions on the general public this week, newly released documents show how the province’s hospitalization projections have evolved since restrictions were lifted.
Using access to information legislation, the CBC obtained updates on COVID-19 modeling prepared by the Department of Health and Welfare’s Analysis Unit.
The updates show the province’s projections of how many people will need urgent care hospitalizations and intensive care unit admissions between January and the end of May. The models were updated at least 13 times during this period as new information became available.
Tara Moriarty, an infectious disease researcher and associate professor at the University of Toronto’s Faculty of Dentistry and Medicine, said all pandemic modeling needs to be updated frequently. “The situation is changing all the time and we have to keep changing,” she said.
Tara Moriarty is an infectious disease expert and researcher at the University of Toronto. (Lisa Sin/CBC)
Moriarty is part of a group of scientists called COVID-19 Resources Canada. The group hosts a weekly online discussion, supported by the Public Health Agency of Canada, where scientists volunteer to answer questions about COVID-19 for the public.
“The patterns are usually pretty good for the next month or so, and then if there’s uncertainty about new things that might happen, that can change what those patterns are,” she said.
An important change to the Nova Scotia models occurred between the February 23rd release and the next March 28th release.
(CBC News)
The February pattern showed that the number of patients in emergency care steadily declined in March, April and May.
However, on March 28, the think tank presented a new version that showed that the number of patients in emergency medical care rose again in April to more than 50 patients and leveled off in May and June.
This comes after reopening measures that began with phase one on February 14 and reached full reopening in phase three by March 21.
The modeling group analyzed the virus’ reproductive number, a measure of how quickly infections spread. A reproduction number higher than one indicates that cases are increasing, and a number lower than one indicates that they are decreasing.
The presentation stated that playback numbers began to rise “soon after reopening phase 1 (February 14), reached a level of around 1.8-2.0 by March 15 (phase 2) and remained at that level in for 10 days (phase 3).”
The March 28 model accurately predicted the number of people in urgent care during what the modeling team called the “post-reopening wave” would not exceed 90 patients at a time, which is roughly how many people were admitted during the peak of the wave Omicron.
The model also predicts a “prolonged plateau in hospitalizations.”
At a media briefing Monday, Dr. Robert Strang, Nova Scotia’s chief medical officer of health, defended the province’s choice to reopen.
“For two years, we learned lots and lots about the virus,” he said. “We’ve learned a lot more about how it’s transmitted, and a lot of the measures we put in initially weren’t really necessary to limit transmission.”
Strang also noted that vaccines are highly protective against severe disease.
Dr. Robert Strang gives an update on COVID-19 on February 9, 2022 (Communications Nova Scotia)
“Our public health response has always been to minimize overall harm, not just minimize the harm of COVID. All of these strict restrictions had a significant impact, whether it was financial or mental health. We are now seeing significant health impacts from delayed access to care due to some of the restrictions in place in our healthcare facilities. We continue to work to find a balance that limits the overall damage.”
The modeling team noted that during the Omicron wave, the province did not have an accurate count of people getting sick, and therefore it was not possible for the models to predict the daily number of cases. The modeling group therefore focused on predicting hospitalizations and ICU admissions.
None of the models attempted to predict the number of deaths.
what’s going on now
As of Wednesday, Nova Scotia has lifted all community COVID restrictions, although a few restrictions remain in high-risk places such as long-term care homes.
“I don’t expect lifting the restrictions to have a big impact on its own,” Strang said when asked how the move would affect the health care system. “We have to look at the bigger picture, not just the health system.
The patterns from late May provide a glimpse into possible future scenarios where ICU and ICU patients decline in July and early August.
The late May pattern indicates that the playback number fell below one in April and continued to fall in May. By August, it is projected that there will be an average of five patients in emergency care and three in intensive care.
“We will still see some cases in the community (travel-related, random/sporadic or localized outbreaks),” the presentation warned.
Jack Woodhead becomes the first child in Nova Scotia to receive a COVID-19 vaccine at the IWK Health Center on December 1, 2021 (CBC)
In an email this week, the Department of Health confirmed that the hospitalization pattern was last updated on June 28 and that pattern was consistent with earlier forecasts.
Isolate when you are sick
Tara Moriarty, an infectious disease expert and researcher at the University of Toronto, said she is concerned about the spread of the BA.5 Omicron subvariant and thinks this week is “not the right time” to lift the mandatory self-isolation requirement in Nova Scotia.
However, she said what happens next will depend on how the public behaves. “Making it mandatory may not have had much of an effect on people’s behavior,” Moriarty said.
“It’s possible for a lot of people to isolate themselves, and whether they have to or not, [Public Health] don’t believe it will have an effect. But overall, you absolutely want to send a message to people that you should isolate yourself when you’re sick.”
A person is swabbed for a COVID-19 test in this file photo. (Steve Lawrence/CBC)
The forecasts posted on CBC were created before this week’s changes were announced. The province says those models did not take into account the announcement made Monday, but adopted “minimum public health restrictions and good public awareness and compliance.”
They do not show how the weakening of immunity from vaccinations will affect hospitalizations, which the modeling group says will need to be taken into account in the future.
Strang said this is an area the National Advisory Committee on Immunization (NACI) is studying and his department is incorporating its guidelines. “Last week they released some recommendations on fall boosters, which we’re now starting to look at,” he said.
One scenario generated in early May shows the modeling team considered the possibility of an early summer outbreak between June 15 and July 30, which would result in community spread in about four weeks.
“This epidemic shows minimal impact on emergency care admissions,” the modeling presentation states.
Strang said his department knows there is a possibility of resuming the newer Omicron subvariants later in the summer, but no specific plan has been developed for that possibility.
“We know all the measures we’ve used for the last two and a half years,” he said, noting that the department will assess the severity of each outbreak. “We’re going to go back to the tools we used before.”
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