Is It Possible to Catch Coronavirus Twice?

You may think that the only good news after testing positive for the coronavirus COVID-19, also known as SARS-CoV2, in addition to surviving it, would be to be immunized against coronavirus, at least during this pandemic episode. But is that true? Chinese and Japanese studies seem to say the opposite.

For example, two journalists Daniel Leussink and Rocky Swift reported that a Japanese tour bus driver tested positive for the virus after curing it. Does this mean that contamination after the virus is possible, or is it an isolated case? After all, a simple case proves nothing, this woman may have had a particularly weak immune system.

However, another case like this occurred, according to a report by NHK Japan. This time, a 70-year-old man tested positive for SARS-CoV2 on February 14 during a cruise. After being transferred to a medical center in Tokyo, he was allowed to go out after testing negative for the virus. He left the medical centre on March 2 and returned home by public transit. But the man became ill again and his fever caused him to return to hospital on 13 March. The next day, he tested positive for coronavirus.

Then there was the article by Caixin, (a Chinese media group) published on 14 February: “14% of patients cured of Covid-19 in Guangdong again tested positive”. The veracity of his figures is more than dubious. Nevertheless, the CGTN explained in a public announcement that antibodies, although present, sometimes do not last very long and that there is indeed a risk, in some cases, of reinfection.

But it should be noted that all this information is peddled by journalists. They are not yet the subject of scientific studies. Indeed, they must first check the tests carried out. After all, the error is human, and it is possible to get a positive result even if the person tested has not been infected with the virus. But on the other hand, being tested negative doesn’t mean you don’t have the virus. This is why doctors can test you several times to be sure of the final diagnosis.

At the same time, scientists need to ensure that patients have been infected again and that it is not an infection that would have lasted a long time. Indeed, what if the cruise passengers and the bus driver had simply been tested and remained infected all this time? Second, the amount of antibodies generated after exposure to any virus depends not only on the virus itself, but on the surprise effect and time the antibodies respond to the virus.

When the immune system faces a new threat, it can only respond in an emergency because it is not ready to repel an unknown invader. However, exposure to the virus through a vaccine or infection can prepare your immune system so you don’t get caught. If it is strong enough, the immune system will then be able to defend itself adequately against the virus in the case of a new infection.

But then could cases of reinfection be particularly weak people with immune systems? Or are there cases or indications that our immune system could not constantly protect against coronavirus? A January 2020 paper in the Journal of Medical Virology summarized all that is known about the immune system’s response to different types of coronavirus. Indeed, the immune response is not necessarily the same against two different types of coronavirus. The immune system must also remember the virus, and over time it is possible that protection drops and allows free passage to a forgotten virus. The question then is: how long can the immune system remember the virus?

As the problem is recent, there are not enough scientific studies that can tell us how the immune system reacts to SARS-CoV2 exactly. So we have to look at studies describing other types of coronavirus. The closest type to SARS-CoV2 is its cousin, SARS (Severe Acute Respiratory Syndrome), which struck in 2002 and 2003.

A 2007 study published by a research laboratory in Shanxi Province, China, called Emerging Infectious Diseases, was conducted on 176 patients with severe symptoms of difficulty breathing. As a result, the average number of SARS-specific antibodies remained the same in the patient’s blood for two years. Then in the third year after infection, the amount of antibodies dropped drastically. This would mean that the immune protection against SARS is maintained for 2 or 3 years and that a new infection would be possible beyond three years.

But keep in mind that antibody levels are not always correlated with immunity. Some people may be protected against a virus without having antibodies detected, while others may be infected with the virus despite the presence of antibodies. The only way to be sure would have been to re-expose these people to the virus and see what happens. This is not an acceptable experience.

The other question is: how many different types of SARS-CoV2 exist? It is difficult to answer this question without more detailed testing. According to a study published in the scientific journal National Science Review, an analysis of 130 cases of COVID 19 showed that there are two types of SARS CoV2. But that does not mean that protection against one is not valid against the other. Over time, the virus may as well mutate and render other types obsolete for the immune system. After all, the mutation is what allowed the virus to spread from an animal to a human.

Not knowing how the immune system works against SARS-CoV2 and how long protection against the virus lasts is a real public health problem. Many analysts believe that once most of the population is infected, it will be immunized, and therefore the pandemic will disappear. Group immunity is the percentage of the overall population that is immune to a given pathogen. Once this percentage is high enough, it will be more difficult for the virus to find people to infect. The theory is that once 70% of the population is immunized, SARS-CoV2 will stop spreading.

But all this is wrong if it is possible to be infected several times or if there are enough different versions of the virus for it to survive. These possibilities are sufficient to call into question this theory of group immunity that is being debated in the United Kingdom.

Since to date no vaccine is available for SARS-CoV2, it is a question of allowing individuals with a strong immune system to be infected several times to reach 70%. But this technique contains far too many risks. The mortality rate for COVID-19 appears to be stagnating between 1 and 3.4%, which is not as much as SARS in the past, but still more than a bad flu. As it is not known if it is possible to be reinfected by the virus, this technique does not make sense. Not to mention that this would be contrary to the processes of protection of the population such as containment and social distancing.

Needless to say, with all these questions that are troubling scientists about this new coronavirus, it should not be taken lightly. Therefore, any patient who cures coronavirus must remain vigilant and follow safety guidelines until the pandemic episode is over. This means staying away from gatherings, washing hands for a long time and frequently, not touching your face, and actively cleaning surfaces and objects.

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