What will be the impact of COVID-19 and influenza this fall and winter? | Coronavirus

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What will be the impact of COVID-19 and influenza this fall and winter? | Coronavirus

How will the COVID-19 pandemic over the next few months? And what additional impact will influenza have? The answer is not entirely clear, but the experts explain the different possible scenarios.

Health Canada has authorized a new version of Moderna's vaccine as a booster dose. The COVID-19 vaccines offered so far have only targeted the original strain of the virus, while the bivalent vaccine is designed to better recognize the Omicron BA.1 subvariant.

If we are currently observing a certain stabilization of new COVID-19 infections, Benoit Barbeau warns that the pandemic is not over and that we must remain vigilant. “We don't know what will happen in the fall, but hopefully it will be a good omen. But the game is not entirely won. “, says the professor in the Department of Biological Sciences at UQAM and specialist in virology.

Unlike last year, there are no more sanitary measures in place, recalls Mr. Barbeau. When the temperatures go down, people will be more inside, we should expect an increase in cases.

According to Marc Brisson, director of the COVID-19 Modeling Group at Laval University and the National Institute of Public Health of Quebec (INSPQ), who recently published hypothetical scenarios of the evolution of the epidemic, several factors will determine the extent to which COVID-19 will have an impact in the coming months, including the type of variant in circulation and the maintenance of hybrid immunity, which is the immunity acquired by an infection in a person vaccinated.

Mr. Barbeau believes that the fact that so many people have been infected and vaccinated in recent months reduces the risk of a major new wave early this fall.

If the government has officially recorded less than 1,500 cases per day this summer, the INSPQ estimates that between 3.3 million and 4.6 million Quebecers have been infected since May. About a million Quebecers were infected in August and September alone.

According to Brisson's team report, as of June 1 (before the last summer surge), an estimated 65% of the population had hybrid immunity; 15% had natural immunity (unvaccinated, infected population); and 15% had vaccine immunity (vaccinated, uninfected population). Less than 5% of the population has never been vaccinated or infected.

An infection boosts their vaccine-acquired immunity, but Brisson says it's still hard to say for sure how long these people are actually protected by this hybrid immunity. This protection diminishes over time – especially in the face of infection and the risk of hospitalization, he reminds.

< p>“Three months ago, the hybrid immunity [observed by the INSPQ in healthcare workers] was very strong. Have we had a gradual decline since then? This element needs to be monitored. »

— Marc Brisson, Director of the COVID-19 Modeling Group at Université Laval

As people's immunity wanes, cases of reinfection within a short period of time are likely to be more frequent, warns Barbeau.

Before the arrival of 'Omicron, reinfection was said to be rare before 90 days. The presence of several subvariants means that a person can be infected several times by a different version of the virus in a short period of time. We have seen people reinfected after four weeks, he says.

In addition, many people received their last dose of the vaccine more than five months ago, which could have an impact on the evolution of the pandemic. Only 23% of Quebecers currently have up-to-date COVID vaccination coverage, according to the Ministry of Health and Social Services.

In Quebec, it is possible to obtain one box of self-tests per month free of charge from a pharmacy.

If the situation seems to have stabilized for a few weeks, the number of cases and deaths remains very high compared to the same date last year, warns Mr. Barbeau. Any new upsurge could certainly have a pronounced impact, he says. in the report prepared with Mr. Brisson.

“Even if the new variants are less severe, the large number of cases could cause significant disruption in society and pressure on the health system. health. »

— Patricia Hudson, Scientific Director of the Biological Risks Department at the INSPQ

Moreover, remember that the very high number of infections by Omicron led to a significant number of deaths. For example, from August 1 to September 15, 2022, nearly 700 Quebecers died from COVID-19. In comparison, during this same period, there were 84 deaths in 2020 and 49 in 2021.

In the scenarios studied by Mr. Brisson, if hybrid immunity is maintained, the impact of a new wave caused by a variant similar to BA.4 and BA.5 could be limited.

In the event of a loss of immunity (natural, vaccine or hybrid), an upsurge in cases and hospitalizations could occur.

If a new variant escapes hybrid immunity, the number of cases could surpass that of the Omicron wave and lead to a significant number of hospitalizations.

For now, it is still difficult to say with certainty which variant will take the place of the BA.4 and BA.5 which currently dominate across the world. Will one of the circulating variants become dominant? Or will we see another variant appear, as was the case with Omicron?

“What will be decisive, c That's how different this new variant will be from BA.4 and BA.5. If these subvariants are different enough, they could lead to a fairly large new spike in infections. »

— Marc Brisson, Director of the COVID-19 Modeling Group at Université Laval

In particular, BA.4.6 is monitored. In the UK, the proportion of cases caused by this subvariant increased from 3.3% to almost 10% in one month. This same variant currently accounts for 10% of cases in the United States. In Quebec, it accounts for nearly 20% of new cases.

Preliminary data show that BA.4.6 is no more severe than BA.4 or BA.5 , but that it would be even more transmissible and more adept at evading immune protection.

A preliminary study that has not yet been peer-reviewed has also shown that monoclonal antibody treatments seem less effective against BA.4.6.

More , this week, WHO recommended discontinuing the use of two other monoclonal antibody treatments – sotrovimab and casirivimab/imdevimab – as they are no longer considered effective against the different subvariants. from Omicron.

Another Omicron sub-variant, BA.2.75, is responsible for increases in infections, particularly in India, and has been detected in about 20 countries. While it has not yet spread significantly around the world, scientists are monitoring it, as it is more transmissible than BA.5 and appears to cause more reinfections.

Each year, countries in the northern hemisphere observe the influenza season in the southern hemisphere to get a better idea of ​​what lies ahead and to adapt vaccines to circulating strains.

This year, Australia experienced its strongest influenza season in five years. The season also started earlier. It is mainly young children who have been infected. On the other hand, severe complications were observed more in the elderly. The country reports 295 influenza-related deaths, and the median age of those who died was 82.

Number of influenza cases in Australia. The red line represents the year 2022.

It is for this reason that the Government of Quebec has chosen to bring forward its influenza vaccination campaign. Seniors and vulnerable people are strongly recommended to receive a vaccine. It is possible to get a COVID-19 vaccine at the same time as the flu shot.

Mr. Barbeau recalls that it is possible to be infected successively by the flu and COVID-19 and that it is possible for a person to be infected at the same time by COVID-19 and by influenza. A vaccine against COVID-19 does not protect against influenza.

Yes, both viruses cause similar symptoms, Barbeau says, but it's still important to test for COVID-19. It's the only way to reliably tell the two viruses apart, and self-testing remains an important tool, he says.

A study published this week in the < /em>British Medical Journal shows that the efficiency of self-tests for COVID-19 decreases from about 80% to about 70% for the Omicron variant. However, people who take a sample not only from the nose, but also from the throat and cheeks, see the self-testing efficiency return to almost 80%. This is what the Quebec government has been recommending for several months.

In order to to increase the chances of detecting the virus, it is recommended to rub the inside of each cheek for at least 5 seconds before taking the sample from both nostrils.

He recommends that people who haven't had a dose of the COVID-19 vaccine in more than five months go get a new dose.

Mr. Barbeau reminds anyone who has symptoms resembling the flu or COVID-19 should take precautions such as wearing a mask in public and staying home.

This is not is not a matter of being alarmist, but of having a conscience. We must take action to avoid being a source of transmission. The [COVID-19] virus is less active at the moment, but we don't want to give it a boost that could lead us to another more difficult wave than the previous ones.

Finally, Mr. Barbeau believes that we should talk more about adapting to the virus than living with the virus.

The virus continues to adapt and we must do so also, depending on what the virus gives us, he says, adding that one day the virus should become more stable, as it does with the flu.

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