Everything you need to know to face the seventh wave of COVID-19 | Coronavirus

risk of contagion of the virus

Currently, the Omicron subvariants BA.4 and BA.5 are responsible for the increase in the number of cases. These subvariants are much more contagious than those observed since the beginning of the pandemic.

The reproductive number (R0) of the original strain of the COVID-19 virus (alpha) is 3.3, meaning one infected person infects about three others.

On average, someone infected with BA.4 or BA.5 infects 19 people. These variants are therefore as contagious as measles, the virus once thought to be the most contagious in the world.

It’s too early to say for sure if these subvariants cause more severe symptoms.

Some analyzes indicate that they would not be more severe than those of other strains of Omicron, but a Japanese study (New window) (not peer-reviewed) shows that they appear to replicate better in the lung than other omicron variants. This suggests that they can lead to more serious complications than other Omicron subvariants. In addition, hospital admissions and deaths are increasing in several countries.

Is this increase caused by a more virulent strain or by a very high number of infections? The answer is not yet clear.

For this reason, experts would like to remind that the virus has not disappeared, although the authorities have lifted most of the restrictions and obligations. So you have to be alert and careful.

Use self-tests

Without testing, it is not possible to tell with certainty whether the symptoms are of COVID-19 or of another infectious disease.

Even with these new sub-variants, the rapid self-tests remain very effective in determining whether a person—asymptomatic or not—has a high viral load and is therefore contagious at the time the test is performed.

Self-testing at home can also detect infections in asymptomatic people.

When should we be tested? If you have symptoms or if you want to check your risk of contagion before visiting someone at risk.

Remember to rub the swab on the inside of both cheeks and then the back of the tongue before rubbing both nostrils.

The results of a self-test are good for a few hours. You can get a positive result the next day, so it’s important to test yourself a few times.

An infected person—especially if they have been vaccinated—may test positive a few days after symptoms appear. If you have had contact with an infected person or have symptoms similar to COVID-19, you must therefore test yourself for a few more days and wear a mask in public as a precaution.

In Quebec, a person is entitled to one box of five free self-tests per month; They are available in pharmacies. In Ontario, some pharmacies and grocery stores offer five free tests per family.

Photo: The Canadian Press/Jeff McIntosh

The presence of a colored band – even a very faint line – indicates a positive result. The probability of a false positive result is very small.

The intensity of the band’s color does not indicate whether one is highly or mildly contagious. It only indicates whether you are contagious or not.

The result is positive? With public health almost no longer tracing contacts, we must try to notify people we have recently encountered. These people may be on the lookout for symptoms, a gesture that can help stop the chain of transmission.

Isolation… longer than five days

In Quebec, as well as several other provinces and territories in Canada, public health officials recommend that an infected person (including those without symptoms) isolate themselves at home for five days. No grocery store, no restaurants; We don’t come to work and we don’t use public transport.

Keep in mind that the Quebec government requires that an unvaccinated person who comes into contact with an infected person self-isolate before receiving a positive test.

If a family member tests positive, other members of that family should test themselves for a few days. As a precautionary measure, until the results of these tests are confirmed, these people are advised to wear a mask in public.

The rules say a person can be released from self-isolation to carry out essential activities after five days if symptoms improve and they have been fever-free for 24 hours without taking fever medication.

However, you must wear a mask for an additional five days.

Why? The fact is that many people are still contagious after five days. The absence of symptoms after a few days does not guarantee that one is no longer contagious.

This analysis (New window) from Harvard University and MIT states that about half of people infected with Omicron (regardless of their vaccination status) are still infectious after eight days.

Another study (New window) observed that 80% of those infected still had a positive result after five days; the same in 61% of cases after 10 days.

Do you absolutely have to go back to work or leave the house after five days? Wear a mask (preferably a KN95 or N95 mask) at all times, reduce your contacts (especially with vulnerable people) and avoid crowded places (eg: festivals, restaurants, etc.).

Wear a mask, keep your distance and ventilate

A KN95 mask held by two hands.

KN95 masks offer better protection than cloth and surgical masks.

Photo: CBC/Maggie MacPherson

Wearing a mask is no longer required in most public places. However, health authorities and health experts strongly recommend wearing one in certain cases:

  • On public transport;

  • in closed and crowded places;

  • in healthcare facilities;

  • in pharmacies.

While non-medical (cloth) masks can help prevent the spread of COVID-19, medical masks and respirators (N95/KN95) offer better protection, especially against the highly contagious sub-variants that are in circulation.

According to a study by Yale and Stanford Universities, surgical masks are 95% effective at filtering out virus particles, compared to just 37% for cloth masks. (New window) (New window)

Do you gather indoors? Improve ventilation by opening a door or window or turning on your range hood and bathroom fan for a few minutes every hour.

A reminder for outdoor gatherings: transmission of the virus is less common outside, but not impossible, especially if you are close to an infected person.

air transmission

SARS-CoV-2 is not only transmitted by large droplets when sneezing or coughing, but also by exhaled aerosols when speaking or singing. Thus, the virus can float in the air we breathe, like second-hand smoke, for several minutes or even hours.

Reinfections: what do we know?

At the beginning of the pandemic, reinfections were rare. Authorities estimated an infected person was protected for around 90 days and it was thought that infection could offer the same protection as a dose of vaccine.

However, since the arrival of Omicron, due to its many mutations, this is no longer the case as newer subvariants – and BA.5 in particular – are more successful at evading natural immunity or the vaccine.

Yes, infection allows some immunity to be acquired. However, this is generally less lasting than vaccine immunity and does not protect against other circulating subvariants.

Researchers from Imperial College London (New window) have also shown that a person infected with Omicron acquires almost no natural immunity to the virus. This ensures, the researchers say, that people are ad nauseam“,”text”:”à risque de réinfection ad nauseam”}}”>there is a risk of reinfection to the point of vomiting.

In this context, a recent infection does not equate to a vaccine dose. Immunity acquired by vaccination is preferred.

Vaccination: how many doses and when?

When we talk a lot about the fourth dose, we have to remember that 45% of Quebecers have not yet received their third (or booster) dose.

Why get a third dose of vaccine when the Quebec government still considers those who have received two doses of vaccine adequately vaccinated? This is because the number of antibodies produced by the immune system decreases over time.

The booster dose does not prevent all infections, but it does allow the immune system to restore sufficient levels of antibodies to prevent serious complications from Omicron infection. The antibody count rises rapidly to an appropriate level one to two weeks after receiving the booster dose.

The fourth dose is currently recommended for people who are more vulnerable or at risk of complications from COVID-19, but it should be remembered that in Quebec it is available to all adults who wish to receive it. The only condition: wait three months since an infection or a last dose before getting a new dose.

These tips were developed with the help of Dr. Anne Bhéreur, general practitioner in palliative care, Matthew Oughton, infectious disease specialist and assistant professor at McGill University School of Medicine, and Nimâ Machouf, consultant in infectious disease epidemiology and lecturer at the School of Public Health at the University of Montreal.

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