Home LATEST NEWS HEALTH What we know about COVID-19 reinfection in the Omicron era

What we know about COVID-19 reinfection in the Omicron era


It is not clear, however, how serious this risk is. Testing is limited across the country and so is detailed publicly available COVID-19 data.

There is a shortage of tests at present and some information suggests that rapid antigen tests are not as accurate as we hoped against Omicronsays Jennifer Gommerman, professor of immunology at the University of Toronto and the Canada Research Chair in Tissue-Specific Immunity.

Prevalence is a difficult question to answer, but we know the virus is circulating a lot.

Rapid antigen tests.

Access to PCR testing in Canada is limited, so many Canadians have turned to rapid tests to find out if they have COVID-19.

Photo: The Canadian Press/Jeff McIntosh

PCR test positivity rates, hospitalization figures as well as sewage data in many provinces indicate increased transmission of the virus.

And data from around the world shows that the risk of reinfection is higher with Omicron, note other specialists.

Usually milder reinfections

When we think about this notion of reinfection, we have to understand that we are still dealing with a virus that is highly capable of bypassing our frontline defenses to neutralize our antibodies.says Jason Kindrachuk, a virologist and assistant professor of medical microbiology and infectious diseases at the University of Manitoba in Winnipeg.

Still, cases of reinfection don’t usually cause disease symptoms to worsen, says Kindrachuk, who also holds the Canada Research Chair in Molecular Pathogenesis of Emerging Viruses.

There are many factors that explain why a person can become reinfected with the virus. Thus, researchers are trying to better understand how the virus can infect us again and what this means in the Omicron era.

Increase in the number of reinfections worldwide

Data released by Public Health Ontario last week shows that 11,730 Ontarians have been re-infected with COVID-19 since November 2020.

According to provincial health officials, reinfection is confirmed when a person has received two positive results for SARS-CoV-2 contamination following laboratory tests which prove that it was distinct infections caused by different virus strains.

South African scientists had warned in December that reinfections among people who have already fought COVID-19 appeared to be more likely with the Omicron variant than with earlier mutations of the coronavirus.

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A recent increase in the number of cases of reinfection has been observed in some parts of the world, for example in the United Kingdom, which has deployed a vaccination campaign similar to that of Canada.

Before December 6, the proportion of daily cases in England considered to be reinfections had been below 2% for almost six months.

That rate is estimated to have risen to 9.9% in February, according to an analysis of UK public health agency data conducted by Reuters.

In Italy, a spokesperson for the National Institute of Health said in February that reinfection cases accounted for around 3% of all infections, compared to around 1.5% before Omicron.

Why does reinfection occur?

Many factors explain why someone is reinfected, including vaccination status and when they received a vaccine or had an infection, according to Dr. Lynora Saxinger, an infectious disease specialist at the University of Alberta in Edmonton.

A study carried out in Qatar and published in the New England Journal of Medicine last month found that healing from a previous infection was about 90% effective in preventing reinfection with Alpha, Beta and Delta variants.

Protection against reinfection with the Omicron variant was less than 60% but remained considerablethe authors said.

Another crucial aspect of reinfection risk is vaccine-induced immunity.

A person fills a syringe.

Experts recommend people get vaccinated to better protect themselves from COVID-19.

Photo: Associated Press / Christophe Gateau

The strength of the immune response will depend in part on a person’s age and overall health. The very old, very young, and immunocompromised will have weakened responses, for example.

This is why the fourth doses are now being distributed to the most vulnerable populations throughout the country.

Furthermore, although vaccines have repeatedly proven effective in preventing serious illnesses and hospitalizations, Omicron is still good enough to get through the equivalent of two doses and in many cases two doses plus infection or three dosespoints out Dr. Saxinger.

Antibodies have been known to disappear over time after a person has been vaccinated or infectedcontinues Benoît Barbeau, professor in the Department of Biological Sciences at the University of Quebec in Montreal, who studies virology.

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days after being infected”,”text”:”So if you were infected in December or early January, you will already have fewer antibodies. This does not mean that you have completely lost your protection against infection, but you will certainly have less protection than say 10 days after being infected”}}”>So if you were infected in December or early January, you will already have fewer antibodies. This does not mean that you have completely lost your protection against infection, but you will certainly have less protection than, say, 10 days after being infected.he explains.

The good news is that the immune response generated by vaccination is strong enough to keep us from getting a really bad disease and ending up in the hospitalcontinues Jennifer Gommerman.

That’s why experts recommend people get a booster dose to boost the onset of that extra protection.

Regarding the BA.2 subvariant of Omicron, early research in Denmark suggests that reinfections with this strain appear to be rare.

What do we need to learn?

Benoît Barbeau assures that as certain regions of Canada and other countries are subjected to a sixth wave, more data will emerge on the people who are reinfected and on the reasons for which they are.

There will be other variations. The risk of reinfection will always be therehe warns.

However, he points out that population immunity, whether from vaccines or previous infection, is building up and allowing us to reduce transmission rates as well as the number of hospitalizations.

In addition, research continues to improve vaccines, whether adapting to new variants or discovering new methods for administering vaccines, in particular through the nasal cavities, notes Mr. Barbeau.

It is very important to continue to improve vaccines.

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