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Difficult to predict when the peak of the 5th wave will be reached | Coronavirus

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According to the acting national director of public health of Quebec, Luc Boileau, Quebec would have already passed the peak of the cases. He said Tuesday during a press briefing that a slowdown in the number of new hospitalizations suggests that the worst is behind us.

But, according to Simona Bignami, associate professor in the Department of Demography at the University of Montreal, governments must remain very cautious. This is still a very uncertain situation., she says.

Since we are testing the population in a very limited way, it becomes more difficult to project into the future, says Ms. Bignami. In addition, the return of students to class adds another element of uncertainty to the equation.

She adds that it is possible that we will observe a temporary decrease in hospitalizations, before seeing an increase about two weeks after the opening of the schools. It will depend on the age groups infected, the proportion of young people who have received their vaccine and the adults who have received their third dose. It’s still hard to know.

According to her, it would have been more prudent to wait a week to see if the slight slowdown observed is real.

Same story for Marc Brisson, professor of mathematical epidemiology and director of the research group in mathematical modeling and health economics related to infectious diseases at Laval University.

If we rely only on new hospitalizations, it seems that we have plateaued. So it’s possible that we’ve reached the peak of the wave. But he says it’s hard to say exactly when or on what day the summit will take place; rather, you have to watch the trends, and not just a decline over one or two days.

Mr. Brisson, who notably makes projections for the National Institute of Public Health of Quebec (INSPQ), recalls that, even if the peak of this wave has been reached, this wave is far from over.

It is possible that Quebec will reach a plateau which may stagnate for a while. […] Also, a wave can have multiple peaks. And there are different peaks for different health outcomes [cas, hospitalisations, décès]. »

A quote from Marc Brisson, Laval University

One thing is certain, says Mr. Brisson: the situation is still very fragile. Even if it goes down again, there are still many cases and hospitalizations and deaths to come. […] This summit is also much higher than what we have seen since the beginning. If there is a too rapid increase in contacts [après l’atteinte de ce sommet], which means that there could be an upsurge. It cannot therefore be excluded.

Projections more difficult to make

Ms. Bignami and Mr. Brisson add that the situation to come in the coming weeks remains unclear because some data is no longer available or is partially available.

We still have a solid base, but we have less information to interpret and validate our projections. Now, if we make projections, it’s harder to give feedback to see if what we’re projecting is good, explains Mr. Brisson.

On January 13, the National Institute of Excellence in Health and Social Services (INESSS), which regularly produces projections on hospitalizations, indicated in a press release that researchers will no longer be able to reliably produce the prediction report on the risks of hospitalization, since it is based on the number of positive cases declared. INESSS is working to adjust the projection models accordingly.

The capping of screening capacities and the underestimation of the number of cases are among the reasons why INESSS is temporarily suspending the production of its weekly report.

Ms. Bignami also wonders how the government will follow the evolution of community transmission when the data on screening are only fragmentary. The number of cases has always been underestimated in Quebec and around the world, but has been even more so since the arrival of Omicron. According to some estimates, the number of cases in late December and early January was possibly up to 40% higher than reported.

On the side of Marc Brisson’s team, in addition to the underestimated number of cases, we can no longer use the data from the CONNECT study, which assesses whether contacts between Quebecers are increasing or decreasing. The number of participants is now too low, which means that these data risk introducing too much bias into the projections, explains Mr. Brisson.

He adds that it will be important to have more precise data on people hospitalized to fully understand whether some people who are admitted “with”, rather than “due to” COVID-19, were infected before or during their holiday. Nosocomial infections must be taken into account.

Finally, the opening of schools is another important factor that could once again turn the situation around.

If children are generally less hospitalized following an infection, a high number of cases among children and teachers could have consequences on the level of community transmission and thus on the number of hospitalizations, think Mr. Brisson and Mrs Bigami.

At the local level, if parents end up learning by word of mouth how many young people are infected in their child’s class, Ms. Bignami wonders how the population will be informed of the situation at the provincial level. If it’s going badly, we may not know, she fears.

The Institut national de santé publique du Québec (INSPQ) also specifies on its website that since January 7, 2022, the seizure of outbreaks affecting schools, work and childcare is optional and left to the discretion of public health departments. These results should now be interpreted with great caution..

By email, the Ministry of Health indicates that several strategies must be put in place to meet the objectives of monitoring COVID-19 in the community. A survey will be produced in partnership with the Ministry of Education with school service centers to monitor absenteeism caused by COVID-19 in schools in the education network.. It is unclear whether this survey will be optional or mandatory.

According to Mr. Brisson, it is essential to find a way to measure the level of transmission in schools to anticipate what will happen next. It is really important to have valid sources of transmission in young people.

As for the self-declaration platforms for infections proposed by the government or set up by the group COVID Écoles Québec, Mr. Brisson does not yet know if the data collected by this means can be used to calculate their projections. It could be useful, but it will be necessary to validate the data to understand if these data are representative and to understand the biases.

Can we see what is happening elsewhere to predict trends here?

Elsewhere in the world, some countries have noticed a slowdown in the Omicron wave. But it is increasingly difficult to compare oneself with other administrations, in particular because of the vaccination rate which varies enormously from one place to another and the different measures put in place.

For example, in the UK, the number of cases has started to decline, but remains at levels almost twice as high as at the height of the pandemic. The UK also saw an increase in hospitalizations, but did not reach the levels of previous waves.

In contrast, in Canada, the number of hospitalized patients is now twice as high as at the height of last winter’s wave (4,905 Canadians hospitalized on January 12, 2021, compared to 10,076 on January 18, 2022). Quebec also broke records this week for hospitalizations and people admitted to intensive care.

Moreover, while the new wave in the United Kingdom began a few weeks before that of Canada, the curve of hospitalizations is only beginning to descend. So, do Quebec and Canada still have a few more weeks to live before seeing the hospitalization curve decrease? Hard to say.

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