As the recent "peak" of new crown infections gradually passes, various rumors about the new crown continue to appear. Many people are very worried, will there be a second round of infection? Will there be more "powerful" variants? Below, we will analyze the recent 6 rumors together to see which ones are true.
Scientists have found that some people infected with the new crown reappear 2 to 8 days after the infection recovery (negative nucleic acid test), the symptoms of the new crown reappear or the antigen/nucleic acid test is positive, which is called "new crown rebound".
About 10% of people infected with the new crown who are not treated with medication will experience a rebound [1]. Among infected people who have taken anti-new crown treatment drugs (such as Pfizer's Paxlovid, Merck's monogravir, etc.), the new crown rebound seems to be more common.
In the case of Paxlovid, a study in the United States involving hundreds of people found that more than 25% of people infected with the new coronavirus reported a recurrence of symptoms, while 12.5% returned to high virus levels [2] (at which point the antigen test may be positive).
(Symptomatic rebound and viral rebound in infected individuals in studies [2])
However, whether the symptoms will be more severe after the rebound than the first infection is still inconclusive and varies from person to person. Milder manifestations and more severe reactions have been observed, but overall, hospitalizations in "rebound" populations are not high [2].
Rebound after antiviral drugs is not unique to Paxlovid alone. One study observed no significant difference in the risk of COVID rebound between Paxlovid and monoravir [3].
It is unclear why the rebound occurred. The researchers speculate that it is unlikely that the virus is resistant to Paxlovid or monoravir, or that the immune response in rebound people is weak.
In all kinds of viral infections, the recurrence of symptoms is relatively normal, and the whole recovery process is not smooth. Even the common cold can recur after symptoms improve. The resurgence of coronavirus infections may be a similar situation.
As long as the overall point of view, the severity of symptoms is getting milder and the frequency of occurrence is getting lower and lower, don't worry too much.
The first cases of the recombinant strain XAY.2 of Delta and Omicron have been reported in Thailand, raising concerns.
Little is known about the variant, known as Delta Keron (XAY.2), and the patient infected with XAY.2 did not have a severe symptomatic reaction, has recovered and has not caused an epidemic in Thailand. The predominant circulating strain in Thailand remains the Omicron variant BN.1.3 [4].
(Image: BBC News [5])
We may also be wondering, why did Delta and Omicron come together? How exactly is it combined?
This is because Delta and Omicron have been circulating at the same time, and both new crown variants are highly contagious, so it is theoretically possible that the same person can be infected with both Delta and Omicron.
After these two variants enter the human body, they may also infect the same cell at the same time, so that the virus carries two genetic characteristics, thus forming "Delta Keron".
In fact, this Delta Keron is not the first time it has appeared, in January 2022, a combination of these two strains was first detected in France, but no signs of rapid spread have been observed since then [5]. This is only one case found in Thailand.
So with Delta Keron (XAY.2), there's no need to panic too much. At present, there is no news coming into the country, and it is more important for everyone to do a good job of protection in daily life.
Professor Zhang Wenhong, director of the Department of Infectious Diseases at Huashan Hospital affiliated to Fudan University, said that the peak date of the second wave of new coronavirus infection will be between May and June 2023 [6].
The main reason is that the new crown virus continues to mutate, and the variant is "transformed", so that the immune system cannot recognize it in time, and it will not be cleared in time. When the virus invades the human body and reaches a certain amount of virus, the immune system will "after-awareness" detect it and respond immunely, resulting in a series of symptoms.
Therefore, even if you have been infected once, you have formed protective antibodies, but if the virus continues to mutate, it is still possible to cause infection again.
On the other hand, whether it is antibodies formed by infection or immunity acquired by vaccination, the protective effect decreases over time. Usually, immunity will be produced one week after infection, strong when infected for about one month, and gradually weakened by 3~6 months.
Therefore, based on this characteristic of the body's immunity, it is indeed possible that the next wave of infections will occur between May and June.
The new crown virus actually not only attacks the respiratory system, in fact, it affects the entire human immune system, and is aggressive to the human heart and lungs, kidneys, brain, digestive tract, coagulation system, and even male testicles.
Zhao Ren, vice president of Ruijin Hospital affiliated to Shanghai Jiaotong University School of Medicine, once introduced: "Omicron... There are two functions, one similar to SARS function and one similar to AIDS function, which has a significant inhibitory function on immunity, so this part of the patient during the onset, at the peak, his lymphocyte count is very low, and his lymphocyte count is closely related to his prognosis" [7].
At present, many drugs that have an inhibitory effect on the new coronavirus, such as azvudine tablets, ritonavir in Paxlovid, remdesivir, etc., are actually drugs used to treat AIDS. Based on these characteristics, some doctors have proposed that the new crown is not very similar to the flu, but more like "little AIDS".
However, there is not enough evidence to confirm that the new crown virus will have a lifelong impact on the immune system like AIDS, and the main symptoms of the vast majority of new crown patients are still upper respiratory tract symptoms (such as cough, sore throat, nasal congestion, etc.), and can basically heal themselves, and there is no need to panic too much.
Recent studies have found that infected people have a 33-fold increased risk of pulmonary embolism, a 5-fold increase in the risk of deep vein thrombosis, and a risk of general bleeding events 30 days after the diagnosis of the new crown. Moreover, this increased risk may persist for up to six months [8].
In fact, doctors have found that not only is the risk of pulmonary embolism significantly increased, but also acute myocardial infarction. Studies have found that within two weeks after infection with the new coronavirus, the risk of acute myocardial infarction and ischemic stroke increases by 5.6 times and 5.7 times, respectively [9].
Therefore, after being infected with the new crown, even if it has turned negative, such as sudden unilateral limb swelling, skin redness, unexplained sudden chest tightness and chest pain, as well as hypotension, hypoxemia, etc., be sure to see a doctor in time.
Studies have found that among people who have not been positive so far, some people have genes that are "not easy to be infected with the new crown virus". Genes that have been discovered include HLA-DQB1*06, HLA-B*15:03, etc. [10][11][12].
HLA in these gene names refers to leukocyte surface antigens, different types of HLA that have different binding abilities to viruses. In the study, it was found that the vast majority of people carrying the above genes were not infected with the new crown. But not many people carry these genes.
People with such genes are undoubtedly lucky, but doing a good job of protection and vaccination is still the most effective means to prevent the new crown from "coming to the door".
The Spring Festival is approaching, I hope everyone protects themselves, spends the festival well, and accompanies each other healthily.
Reviewer: Jiang Weimin
Chief physician of Department of Infectious Diseases, Huashan Hospital, Fudan University
bibliography
[1]https://www.nature.com/articles/d41586-022-04138-w
[2] Deo, R., et al. Preprint at medRxiv https://doi.org/10.1101/2022.08.01.22278278
[3] Wang L, Berger NA, Davis PB, Kaelber DC, Volkow ND, Xu R. COVID-19 rebound after Paxlovid and Molnupiravir during January-June 2022. medRxiv [Preprint]. 2022 Jun 22:2022.06.21.22276724. doi: 10.1101/2022.06.21.22276724. PMID: 35794889; PMCID: PMC9258292.
[4]https://tech.ifeng.com/c/8MOvgPhytyw
[5]https://www.bbc.com/zhongwen/trad/science-59431055
[6]https://m.gmw.cn/baijia/2023-01/10/1303250521.html
[7]https://k.sina.com.cn/article_6145283913_v16e49974902001olwg.html
[8]https://www.bmj.com/company/newsroom/study-finds-increased-risk-of-serious-blood-clots-up-to-six-months-after-covid-19/
[9] Risk of acute myocardial infarction and ischaemic stroke following COVID-19 in Sweden: a self-controlled case series and matched cohort study. Lancet, July 29, 2021
[10] Mentzer, A. J., O’Connor, D., Bibi, S., Chelysheva, I., Clutterbuck, E. A., Demissie, T., ... & Knight, J. C. (2022). Human leukocyte antigen alleles associate with COVID-19 vaccine immunogenicity and risk of breakthrough infection. Nature medicine, 1-1.
[11] Austin Nguyen, J. K. D., Maden, S. K., Wood, M. A., Weeder, B. R., Nellore, A., & Thompson, R. F. (2020). Human Leukocyte Antigen Susceptibility Map for Severe Acute Respiratory Syndrome Coronavirus Journal of Virology, 94(13).
[12] Ren, J., Pang, W., Luo, Y., Cheng, D., Qiu, K., Rao, Y., ... & Zhao, Y. (2022). Impact of allergic rhinitis and asthma on COVID-19 infection, hospitalization, and mortality. The Journal of Allergy and Clinical Immunology: In Practice, 10(1), 124-133.
*Produced by Tencent Medical Codex Content Team