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


Contagiousness of the virus

At the moment, the BA.4 and BA.5 sub-variants of Omicron are responsible for the rise in the number of cases. These subvariants are much more contagious than those seen since the start of the pandemic.

The reproduction number (R0) of the original strain of the COVID-19 virus (Alpha) is 3.3, which means that one infected person infects approximately three others.

Someone who is infected with BA.4 or BA.5 infects an average of 19 people. These variants are therefore as contagious as measles, the virus that was once considered the most contagious in the world.

It is still too early to say for sure whether these subvariants cause more severe symptoms.

Some analyzes show that they would not be more serious than those of other strains of Omicron, but a Japanese study (New window) (not peer reviewed) shows that they seem to replicate better in the lungs than other Omicron variants. This suggests that they may lead to more serious complications than other Omicron subvariants. Moreover, in several countries, the number of hospitalizations and deaths is increasing.

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

This is why experts are keen to remind that even though the authorities have lifted most restrictions and obligations, the virus has not disappeared. So you have to be vigilant and careful.

Use self-tests

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

Even with these new subvariants, the rapid self-tests remain very effective in determining whether a person – asymptomatic or not – has a high viral load and, therefore, if they are contagious at the time they take the test.

Home self-tests can detect infections even in asymptomatic people.

When should we be tested? When you have symptoms or when you want to check your contagiousness before visiting a vulnerable person.

Remember to rub the swab against the inside of both cheeks, then against the back of the tongue, before performing the two rubs in each nostril.

The results of a self-test are good for a few hours. You can get a positive result the next day, hence the importance of testing yourself a few times.

An infected person – especially if they have been vaccinated – can test positive a few days after symptoms appear. This is why, if you have been in contact with an infected person or if you have symptoms similar to those of COVID-19, you must continue to test yourself for a few days and wear a mask in public, as a precaution.

The presence of a colored band – even a very faint line – indicates a positive result. The chances of a false positive result are very slim.

The intensity of the color of the band does not indicate whether one is highly or slightly contagious. It only indicates whether one is contagious or not.

The result is positive? Since public health is 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… beyond five days

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

Remember that the Government of Quebec requires that an unvaccinated person who is in contact with an infected person isolate themselves even before having received a positive test.

If one family member tests positive, other members of that family should test themselves for a few days. Pending confirmation of the results of these tests, as a precaution, it is recommended that these people wear a mask in public.

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

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

Why? It is that after five days, many people continue to be contagious. 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 indicates that approximately 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 infected people still had a positive result after five days; same thing 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 at all times (preferably a KN95 or N95 mask), reduce your contacts (especially with vulnerable people) and avoid crowded places (for example: festivals, restaurants, etc.).

Wearing a mask, distancing and ventilation

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, public health authorities and health experts strongly recommend wearing one in certain cases:

  • In public transports;

  • in closed and crowded places;

  • in health 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 subvariants that are circulating.

Surgical masks are 95% effective at filtering out virus particles, compared to just 37% for cloth masks, according to a study from Yale and Stanford universities. (New window) (New window)

Read:  not very useful, according to an expert

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

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

Reinfections: what do we know?

At the start of the pandemic, reinfections were rare. Authorities estimated that an infected person was protected for about 90 days and it was believed that one infection could offer the same protection as one dose of vaccine.

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

Yes, an infection makes it possible to acquire a certain immunity. However, this generally lasts less 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 against the virus. This ensures, say the researchers, that people are ad nauseam“,”text”:”at risk of reinfection ad nauseam”}}’>at risk of reinfection ad nauseam.

In this context, a recent infection is not the equivalent of a vaccine dose. Immunity acquired through vaccination is preferred.

Vaccination: how many doses and when?

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

Why receive a third dose if the Government of Quebec continues to consider as adequately vaccinated those who have received two doses of vaccine? Because the number of antibodies produced by the immune system decreases over time.

The booster dose does not prevent all infections, but it allows the immune system to restore sufficient antibody levels to prevent serious complications from Omicron infection. The antibody count quickly rises to an adequate 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 obtain it. The only condition: wait three months since an infection or a last dose before going to get a new dose.

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

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