Đại dịch Covid-19

The reason some people have never been positive for SARS-CoV-2

According to statistics, the US has 80 million infections COVID-19 in and 979,000 people died. But it is a rather strange fact when new and contagious variants appear. That is, all family members have tested positive, except for one person, even though all were vaccinated and exposed to the disease at the same time, in the same way.

Dr Mohamad Assoum, an infectious disease epidemiologist at the University of Queensland, offered several reasons.

The reason some people have never been positive for SARS-CoV-2 - 1

(Artwork: Medpagetoday)

Avoid high-risk areas

Most people get COVID-19 when they breathe in droplets that contain the virus or when those droplets get into their eyes or mouth. An infected person can spread the virus to the outside when coughing, sneezing, shouting, singing loudly…

Some studies have shown that Omicron variants can last longer on surfaces than the parent strain. However, previous evidence has shown that people are more likely to contract the virus from respiratory droplets than contaminated surfaces.

Poorly ventilated spaces, close contact will increase the risk of disease transmission. Experts also recommend wearing a mask, washing your hands often, “sneezing safely” (cough and sneeze into your elbow) and avoiding touching your face. Some have never tested positive because they avoid high-risk environments by working remotely and driving their own cars.

Of course, at some point in the past two years, everyone has had to go into public spaces, go shopping, go to work, visit relatives.

Asymptomatic COVID-19 infection

According to data from the city of Beijing (China), up to 40.5% of COVID-19 cases are asymptomatic. So it’s possible that some people were infected without knowing it because they didn’t show symptoms and didn’t get tested.

According to the Centers for Disease Control and Prevention (CDC), people with no symptoms are also more likely to get a negative result with a rapid test.

Already injected vaccines COVID-19

If a vaccinated person comes into contact with the virus, they have a high chance of avoiding infection. The vaccine doesn’t guarantee you won’t get COVID-19, especially with new variants like Omicron, but it does reduce your risk of getting sick, getting worse, and dying. Many vaccinated people who tested positive reported much milder symptoms.

False negatives

Current SARS-CoV-2 tests are quite accurate, but not perfect. For example, some rapid at-home tests are less sensitive to variations like Omicron. Some people have a low viral load or the wrong sample can also lead to false negatives.

Therefore, if you have symptoms and the rapid test is negative, you can check again with a PCR test. If the PCR results are negative, you likely have another infection.

Do some people have natural immunity against COVID-19?

This immunity is so rare that it is difficult to find cases to study. It has been suggested that some people do not have the ACE2 receptor that the SARS-CoV-2 virus uses to enter cells.

Another view is that people who are resistant to COVID-19 have a very strong immune response, especially in the cells inside their nose.

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