How long does the immunity generated after contracting covid last? – 06/15/2022

When the first cases of covid-19 appeared in the world, no one knew for sure how long the immunity conferred by the virus would last. Would it be permanent, as in the case of measles, or short, as in the other coronaviruses that infect humans?

After more than two years of a pandemic, we already know the answer: a lot of people caught covid more than once. Sars-CoV-2 reinfections are increasingly common. However, until mid-2021 they were much less frequent. “The average duration of the natural protection afforded by infection caused by the delta variant was about three months. That is, a person infected with delta could ‘relax’ for a while, knowing that during this period they would be protected against further infection,” explains medical epidemiologist Denise Garrett.

With the emergence of the omicron variant and its subvariants, this scenario changed. “We are seeing an increase in the number of reinfections and a decrease in the space between them. There are reports of reinfection in up to 20 days”, says Dr. Garrett.

A group of scientists at Weill Cornell Medicine in Qatar calculated that an infection with earlier variants of Sars-CoV-2, such as alpha and delta, was about 90% effective in preventing further infections in people with a diagnosis. prior to covid for at least 90 days.

After the appearance of the omicron, according to the study, a previous infection with the virus offered a 56% protection against another infection. That’s because the virus suffered many mutations in the spike protein that allowed the new versions to become more transmissible and able to escape acquired immunity.

There are other factors that are also responsible for the current high number of reinfections. We know that the immunity conferred by the vaccine or a previous infection decreases over time, so the more months that elapse between vaccination or the first infection, the greater the risk of contracting Sars-CoV-2.

The high circulation of the virus also contributes to reinfections, as it is easier to find it at a time when new cases are increasing and states and municipalities have relaxed prevention measures.

But it’s not all bad news. After a first infection, the body tends to fight another infection more effectively, as the cells of the immune system, such as T and B lymphocytes, “remember” how to face the virus. Thus, a new infection is usually milder than the previous one.

This also occurs with those who have not been infected by the virus, but have had the vaccines against the disease. Vaccinated people can contract Sars-CoV-2, but the infection tends to be less severe and shorter. “Although reinfection also occurs in vaccinated people, it occurs in a smaller proportion than in non-vaccinated people. Therefore, it is essential to take all 3 doses of the vaccine schedule, even if you have already been infected”, insists Dr. Garrett.

Those who took the vaccines and had the infection develop what experts call “hybrid immunity”, that is, a combined protection of pre-existing antibodies generated by the vaccine and the natural antibodies caused by an infection.

However, even hybrid immunity does not guarantee that a person will not contract another infection, as protection varies from individual to individual and also tends to decrease over time.

Seeking to contract the virus to develop immunity, therefore, makes no sense, as it does not last long. In addition, covid can cause prolonged symptoms. There are still no conclusive studies on the percentage of people who develop persistent symptoms after being infected with Sars-CoV-2, but the US Centers for Disease Control and Prevention (CDC) estimates that 1 in 5 people may experience symptoms such as tiredness, difficulty concentrating, loss of smell, among others for periods longer than a month.

The best way to acquire immunity against severe cases of the disease is, therefore, to take the three recommended doses and the booster vaccine, in the indicated cases. The use of a mask in a closed and crowded place and the maintenance of ventilation of spaces offer additional layers of protection that must be used in times of high circulation of the virus, such as the current one.

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She's our PC girl, so anything is up to her. She is also responsible for the videos of Play Crazy Game, as well as giving a leg in the news.

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