Ho Chi Minh CityWorking in the same room, having lunch together for a week with three colleagues who later became F0, but Ms. Thanh Thuy (26 years old) tested negative 4 times in a row.
In mid-November, two roommates who were also infected with Covid-19 had to go away, only Thuy quickly tested negative.
Associate Professor Do Van Dung (Dean of the Faculty of Public Health, University of Medicine and Pharmacy in Ho Chi Minh City) said: Covid-19 immune case like Thuy is not uncommon. Scientists have conducted many studies and pointed out the causes leading to the above situation, according to which:
The first, the corona virus family is associated with many diseases, for example flu, cold, Covid-19. If a person has had a cold, the body already has an immunity to corona, which is saved by immune memory cells. When exposed to the pathogen, which is Covid-19, memory cells are activated, actively eliminating the virus, before they cause symptoms. This is called cross-immunity.
Monday is due to the individual’s immune system. People with strong resistance will attack and destroy viruses, not allowing them to replicate as soon as the virus enters. They may not be infected, or infected with symptoms and a very mild degree, quickly recovering, when tested often do not show the virus.
In addition, people who have been vaccinated with enough Covid-19 vaccine, the amount of antibodies produced is strong enough, the risk of infection is also lower than those who have not been vaccinated. Vaccine efficacy reduces the number of people who would otherwise get sick by about 80%.
The 4th cause is very common, that is, this person has had and recovered from the disease before the time of current exposure to F0. According to Mr. Dung, the Covid-19 test is an antigen test – finding the virus in the nose and pharynx. Meanwhile, many people have Covid-19 but have no symptoms or very mild symptoms (often mistaken for a runny nose, seasonal allergies, cold-season sneezing). With a healthy immune system or already having antibodies due to vaccination that the body handles too well, the disease recovers quickly. Therefore, the test did not show the presence of the virus in the nasopharynx.
Having the same opinion, Doctor Nguyen Hong Ha (Vice President of the Vietnam Infectious Diseases Association) said that this case is actually infected but not known, not immune. In endemic areas (with a large number of people exposed) such as Ho Chi Minh City, Binh Duong will be more common. He thinks that in fact, the number of F0 can be dozens of times higher than the number of infections reported by the authorities, for many reasons.
In addition, Dr. Ha pointed out a number of other immunological causes, such as at the contact stage, the virus concentration in the oropharynx of F0 was still low, had not yet spread or spread little outside. If the office or house is spacious, well ventilated, regularly cleaned and disinfected, it will also reduce the possibility of infection. In particular, there are people who are not susceptible to (not receiving) the virus.
Any infectious disease is immune to the virus, even if they live in the “red zone”. Before there was a vaccine, many people actually overcame dangerous pandemics such as flu, measles, plague, smallpox… and lived healthy to old age. “This is the general law of nature,” said Dr. Ha.
However, “Immune to Covid-19 does not mean that it will be safe for life”, Associate Professor Dung repeated many times. He explained, depending on factors such as location, stage, concentration of invading virus, different strong/weak immunity will determine whether you will get the disease or not. In addition, antibodies are produced by immune memory cells. If there is no frequent exposure to new pathogens, or the body ages, goes through a long time, or has to be treated for some other disease, these memory cells will gradually decrease and disappear. To restore and ensure immune memory, scientists recommend booster vaccination every 5-10 years, such as hepatitis B and tetanus vaccines.
According to experts, Vietnam has not yet reported the rate of Covid-19 immunity for the whole population. At the present stage, this concept is not valid when the vaccine has been given free of charge nationwide to achieve herd immunity. Moreover, to determine whether a person has ever been infected with Covid-19 or not, it is necessary to assess the level of community exposure, epidemiological investigation, do antigen testing, etc. Even with people with special backgrounds, If antigens are not present, more specialized tests such as immune memory cells should be performed. This is expensive and unnecessary.
People who live in the same house, work with F0, especially high-risk people (older, have underlying medical conditions) need to strictly follow 5K and get vaccinated. These two simple measures have been proven effective enough to prevent Covid-19, experts recommend.