Abstract: Although the spread and infectivity of THE NEW CROWN and its variants are strong, clinical manifestations and research results continue to confirm that not all patients infected with the new crown virus will develop serious diseases or even face death. In fact, most of the infected patients develop only mild symptoms, and only a few develop malignant diseases (unvaccinated and underlying elderly people with underlying diseases may have a greater severity) and require hospitalization. According to previous reports, the elderly male group is a high-risk group of infection with the new crown, and the elderly are more likely to cause serious diseases after being infected with the new crown, and the mortality rate is also higher.
The latest research has found that the length and proportion of a person's fingers can actually provide clues to the severity of the new crown virus infection. The researchers counted the proportion of length of the four fingers (index finger, middle finger, ring finger, and little finger) in addition to the thumbs of infected and healthy subjects and explored their association with the severity of post-COVID-19 infection. The proportion of finger length is closely related to the severity of post-COVID-19 infection, and the finger-length ratio may be an indicator of the deterioration of the disease and the risk of hospitalization in PATIENTS. The study, titled "Digit ratios and their asymmetries as risk factors of developmental instability and hospitalization for COVID-19" (Figure 1), was published in Scientific Reports.
Figure 1 Research results (Source: Scientific Reports)
Severe COVID-19 can lead to respiratory and systemic diseases, severe pneumonia in severe patients, acute respiratory distress and multi-organ failure. In the confirmed population, the severity of the condition after the diagnosis of COVID-19 depends on gender (male> female). The excessive number of deaths in men has led to the emergence of two theories: the androgen-driven theory The theory of hypogonadism in men. Both theories involve hormone-related differences in the severity of diseases, so can sex hormone-related indicators be used as predictors of COVID-19 severity? The researchers measured the length of the fingers of the patients and control groups eight times: the length of the second, third, fourth, and fifth fingers (2D, 3D, 4D, and 5D) (right hand (R) and left hand (L)). The following ratios are calculated based on these parameters: 2D:3D, 2D:4D, 2D:5D, 3D:4D, 3D:5D, 4D:5D for right(R) and left(L)hands (D length [mm]/D length [mm]) and directional asymmetry of the ratio (right ratio-left ratio: Δ2D:3D, Δ2D:4D, Δ2D:5D, Δ3D:4D, Δ3D:5D, Δ4D:5D) and unsigned asymmetry (FA) (| (right-left) |) (Figure 2).
Figure 2 Research results (Source: Scientific Reports)
The study came to the following conclusions:
1
The finger length ratio and its asymmetry can be seen as a simple clinical marker that COVID-19 may lead to the risk of hospitalization.
2
The finger-length ratio is affected by sex steroids, which may be evidence of a link between the severity of COVID-19 and prenatal (2D: 4D) and postnatal (3D: 5D) testosterone and estrogen.
3
In countries with high COVID-19 mortality rates, prenatal testosterone levels in the male population are low relative to estrogen levels.
It is known that the shorter length of the ring finger in men is a sign of low testosterone, while the androgen testosterone is associated with the severity of post-COVID-19 infection, so the finger length ratio may be a predictor of severe COVID-19 infection and increased risk of hospitalization after infection with the virus.
Another study on the relationship between COVID-19 case fatality and gender is published in Early Human Development (Figure 3) titled "Understanding COVID-19: Digit ratio (2D:4D) and sex differences in national case fatality rates."
Figure 3 Research results (Source: Early Human Development)
The study concluded the following:
1
In the COVID-19 pandemic, the number of deaths in men is higher than the number of deaths in women. This sex-dependent pattern has also been observed in other pathogenic coronaviruses (CoV), including severe acute respiratory syndrome (SARS)-CoV and Middle East respiratory syndrome (MERS)-CoV.
2
Severe cases in men may provide clues to the pathogenic effects of the new coronavirus and the immune response to these effects.
3
Men tend to produce a weaker immune response than women and are more susceptible to various infectious agents, led by RNA viruses, which leads to testosterone (as well as other sex steroids) that can negatively affect the body's immune system.
Considering the relationship between the COVID-19 case fatality rate and the digital ratio (2D:4D), the digital ratio is representative of the level of prenatal steroids, which is inversely correlated with prenatal testosterone and positively correlated with prenatal estrogen. Case fatality rates vary widely across countries, as do the percentage of deaths among men in each country. The researchers analyzed the relationship between the case fatality rate and the percentage of male deaths from COVID-19 cases, as well as the national average for the male and female numerical ratios. The researchers analyzed the association between the national average of the numerical ratio and the case fatality rate, as well as the percentage of male mortality in 41 countries, to assess two competing views on the relationship between testosterone and prognosis in COVID-19 cases. A negative correlation will support the androgen-driven THEORY of the COVID-19 pandemic, while a positive correlation suggests that male hypogonadism is associated with the severity of COVID-19 cases (Figure 4).
Figure 4 Mortality data of male confirmed cases in the sample (Source: Early Human Development)
Taken together, we found that the national male 2D:4D ratio in the study sample was positively correlated with CFR and the percentage of male deaths due to COVID-19, and the results were not related to the female 2D:4D ratio. Therefore, high prenatal testosterone in men may have a protective effect on the severe impact of the new crown. The findings suggest that the excessive death of men caused by COVID-19 is not a product of high prenatal testosterone, but a marker of hyponatal gonadalism.
Furthermore, it is argued that if the index finger is longer than the ring finger, it indicates that the level of androgen exposure before birth is low and the level of estrogen is high; if the ring finger is longer than the index finger, it indicates that the level of androgen exposure before birth is high and the level of estrogen is low. This finding further suggests that the severity of COVID-19 infection is actually a combination of low testosterone hormone and high estrogen.
Studies in these two literatures confirm that due to differences in the proportion of finger length and symmetry between patients hospitalized for COVID-19 and control, patients have higher levels of developmental instability compared with controls, and attention should be paid to the proportion of finger length involving the little finger. Individuals with high testosterone hormone levels and low estrogen levels are more likely to develop severe acute illness after covid-19 infection. This has amply explained why men are more severely infected with COVID-19 than women, and that older men are more likely to die after covid-19 infection. Although the study has the limitation that the sample size is not large enough and the coverage is not comprehensive, the researchers said that the results still have certain practical significance: it can effectively predict the severity of the new crown confirmed group after the disease, help to target the high-risk population, and also help researchers improve the treatment of the new crown drug, and ultimately reduce the new crown infection rate, hospitalization rate and even mortality rate.
Written by | Qiao Weijun
Typography | Qiao Weijun
End
Resources:
[1] Kasielska-Trojan A, Manning JT, Jab kowski M, et al. Digit ratios and their asymmetries as risk factors of developmental instability and hospitalization for COVID-19. Sci Rep. 2022 Mar 17;12（1）:4573. doi: 10.1038/s41598-022-08646-7. PMID: 35301404; PMCID: PMC8931101.
[2] Manning JT, Fink B. Understanding COVID-19: Digit ratio （2D:4D） and sex differences in national case fatality rates. Early Hum Dev. 2020 Jul;146:105074. doi: 10.1016/j.earlhumdev.2020.105074. Epub 2020 May 14. PMID: 32419720; PMCID: PMC7224643.
[3] Does finger length predict the severity of COVID-19?
[4] Nature found that finger length and proportion may predict how high the risk of developing malignant diseases after contracting COVID-19 is
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