Obtenez-vous une meilleure immunité contre la COVID-19 grâce à la vaccination ou à l'infection ?

Quelle protection offre une infection antérieure par la COVID-19 ?

When you become infected with the virus that causes COVID-19, your immune system reacts in a number of ways. You may get symptoms of infection, which can vary depending on the particular strain. For example, a runny nose, des maux de tête et fatigue are common des symptômes of Omicron.

Une réponse importante est de produire des anticorps. Les anticorps sont des protéines de lutte contre les maladies dans le corps qui jouent un rôle crucial dans le système immunitaire. Les anticorps détectent les envahisseurs infectieux tels que les bactéries et les virus et aident le corps à les éliminer tout en offrant une protection contre les infections futures.

It is known that becoming infected with COVID-19 creates antibodies. Between April and August 2021, researchers behind the étude ZOE COVID examined the antibodies of more than 8,000 people who had tested positive. Of those, 6,609 (80.67%) had a positive anti-N antibody test result - meaning they had some level of protective antibodies.

However, this also means one in five people did not and could therefore be at risk of catching COVID-19 again. Crucially, the risk of reinfection can depend on the strain of COVID-19.

La probabilité de réinfection est plus élevée avec Omicron

Data from the Bureau des statistiques nationales show the risk of reinfection among people who caught an earlier strain of COVID-19 and were then exposed to the Omicron variant is 16 times higher than it was among people exposed to the Delta variant.

In December 2021, researchers at Institut National des Maladies Transmissibles d'Afrique du Sud warned that Omicron has a substantial ability to evade immunity from a previous COVID-19 infection. This suggests the variant could lead to a wave of infections, even in populations with high levels of antibodies.

Les réponses immunitaires peuvent varier

While some people want to rely on having had COVID-19 previously as a form of protection, this is a very risky approach. This is because les réponses immunitaires responses vary widely from person to person.

Although some people's immune systems create an effective immune response - so that they are unlikely to become infected again and thus can't pass the virus to someone else - others may not. Some people may be protected from becoming unwell with COVID-19 again, but can still become infected and can still transmit the disease to those around them.

Various factors can determine the level of COVID-19 immunity someone can get from infection, including underlying health conditions, some medicines and age. For example, les personnes âgées are less likely to have an effective immune response to infection.

"La plupart des recherches is showing that we are seeing multiple infections over time," says Rodney E. Rohde, a professor of clinical laboratory science and an infectious disease specialist at Texas State University. "This means that les vaccins continue to offer the best and longest-lasting protection."

L'immunité contre la COVID-19 diminue avec le temps

Even if someone does gain some immunity from past infection with COVID-19, this immunity lessens over time. According to one étude published in early 2021, people could have a level of infection immunity for at least five months, but they can still carry and transmit the virus.

This study was carried out when Delta was the dominant variant, so may not be relevant to subsequent strains such as Omicron.

Se faire vacciner offre aux gens la meilleure chance de se protéger et de protéger les autres contre l'infection par le COVID-19.

Although current vaccines are less effective against infection with Omicron than previous variants, des études show that vaccination does provide a high level of protection against severe disease and hospitalisation. Getting a dose de rappel jab is the most effective way to protect yourself from both infection and severe illness from Omicron, recherche shows.

"Les vaccins contre la COVID-19 sont recommandés, même si vous avez eu la COVID-19," déclare Rodhe. "Les données de recherche de la Johns Hopkins Medicine et des Centers for Disease Control and Prevention (CDC) des États-Unis conseillent qu'un vaccin contre la COVID-19 offre des anticorps et une autre immunité de plus longue durée qui protègent contre l'infection par la COVID-19, que l'on ait été infecté par le SARS-CoV-2 ou non."

La Étude ZOE COVID suggests that protection via natural immunity is less effective overall than la vaccination.

It's not yet known how long immunity to COVID-19 from vaccines will last. Therefore, it's possible that we may need vaccins de rappel annuels to protect against future variants, particularly for vulnerable or immunocompromised people.

Une infection antérieure au COVID-19 et la vaccination peuvent offrir une bonne protection

There is a growing body of research that suggests infection plus vaccination provides the best protection against catching COVID-19. This combined protection may last longer than vaccination alone, according to a 2021 study published in the journal Science, bien que cela n'ait pas été prouvé.

Ultimately, the only way to get naturally acquired immunity is through infection with COVID-19, which is risky. When you become infected, you can infect other people - including those who are vulnerable - and you can spread the disease. There is no way of knowing just how unwell you may become and those who are unvaccinated are at greater risk of severe illness. And even if you avoid hospital, you are at risk of potentially highly debilitating brochure sur le COVID long, actuellement considéré comme affectant 1.3 million people (2% of the population) in the UK.

However, vaccination allows you to build up your immunity safely, without risking your health and the health of those around you. There have been rare reports of serious side effects seen - such as the risque de caillot sanguin rare, cerebral venous sinus thrombosis (CVST). But the risk of this complication is about 2 in a million from vaccination: the risk of the same clot from catching COVID-19 is 8 à 10 fois plus élevé.

Similarly, while there has been much concern in the media about the risk of myocarditis (inflammation of the heart muscle), in absolute terms the risks are extremely small. A review of 8.7 million COVID-19 vaccines given to children aged 5-11 in the USA showed 11 cas confirmés de myocardite (1 in 800,000), who recovered after a 'mild clinical course'. By contrast, among 12 to 17-year-olds infected with COVID-19, the l'incidence de la myocardite était just under 1 in 2,200.

Not only do vaccines lower your chance of developing COVID-19, they also reduce how unwell you become if infected. Your COVID-19 immunity can be easily enhanced and prolonged by getting injections de rappel over time.