Covid-19 on men and women, what the data on lethality demonstrate (by M. Catellani and M.C. Morrone)


(Edited by Marta Catellani, Lyncean partner; Maria Concetta Morrone, Lyncean partner)

More than 3 months after the start of the pandemic, some data are now sadly established. In some phases of the epidemic we have seen the numbers of infections spread exponentially. The numbers, which provide us with official databases such as those collected by John Hopkins Csse and analyzed by UNwomen or GlobalHealth5050, tell us that the chances of being infected are the same for adults, both for young and athletic people and for people beyond in the years, but without previous pathologies.The probability of contagion does not seem to depend on sex either, but on the work and style and living conditions of individual people. This is true in Italy, in Europe, in China and also in countries that are now experiencing the peak of the infection. It is true both in Italy, Spain, the UK and the USA where the number of the deceased leaves us dismayed at having passed the tens of thousands in a few weeks, and in countries like Korea or Germany where fortunately there are few. A datum emerges stable looking at the gender of the deceased: at all ages lethality (ratio between the deceased and infected) is higher in males than in women (UNwomen data). In Italy the lethality of males is on average twice as high as for women, but it can also reach a factor of 4 in the age group of the fifties (50-59 years), as shown by the report of the Istituto Superiore di Sanità dated 28/4 / 2020.

To understand the phenomenon, it is worthwhile to dwell on some numbers of the aforementioned ratio of 1 to 4: if only 190 women between the ages of 50 and 59 have not made it since the beginning of the epidemic in late April, there are about 720 males in their fifties who left us. It is also appropriate to dwell on the vast audience of the same fifty-year-olds infected: out of about 36,000 (about 19,000 women versus 17,000 males) lethality for women is 1% and for males 4.1%. And the number of 36,000 is certainly an underestimate of the real cases of contagion. This is the number certified by the Istituto Superiore di Sanità and, given the criteria used to access the molecular test by means of a buffer, it does not select the asymptomatic infected (about 15%) and those with minor symptoms (other 15%, data 28/4 ISS).

The other singularity that the numbers tell us is that the lethality of the virus seems to change a lot from country to country. While Italy is unfortunately at the top of the ranking with around 14%, other countries have a very low lethality of 1.4-2.4%, such as Australia, New Zealand or South Korea. But on this point it is wrong make a direct comparison without assessing the age groups, gender and above all the methodological notes that accompany the data collection. The most important parameter to evaluate in the comparison of lethality between countries is the number of swabs carried out and the inclusion criteria that determine whether the patient must be tested for the virus.

Let’s take the case of a very particular category of people such as that of health workers to which all Italians should bring respect and admiration. With the exception of the first period, most of them should be checked with tampons regardless of the symptoms, in line with the provisions issued by the Ministry of Health on March 25, 2020. A category, therefore, whose data could reflect quite correctly the actual number of infected people and, presumably, also include numerous asymptomatic and pauci-symptomatic. A large number of health workers got sick and their number is staggering: at the end of April there were about 20,800 and they made up 11% of the total cases! It is the work-related risk they run by being exposed repeatedly to high viral loads. Well at the end of April, according to the information disseminated by the federations of the categories, the health workers who are no longer among us are just under 200: a very serious loss for the health system – made up of operators with great experience and courage who, in desperate conditions, they gave everything to serve others. The lethality for health workers is therefore about 1%, very different from the terrible 14%. However, health workers have an average age of 48 years, and are predominantly women (75%), who prefer the care work towards the weak and sick; two factors that contribute to explaining the low lethality with respect to the general population. It is therefore instructive to restrict the analysis only to the class of deceased doctors who have a higher average age and a proportion between balanced sex. What emerges is that only 10 doctors died between March and April between the ages of 50 and 59, with a female lethality of around 0.23% and masculine of 1%.

As we said before, lethality for the Italian population in the same age group between 50 and 59 years, is instead 1% for women and 4.1% for males and therefore four times greater than the lethality of doctors: a such a large gap would lead us to think that the estimate of lethality in the general population is wrong. If, however, we analyze the data for the age between 60 and 69, the lethality of the doctors is similar to that of the Italian population of the same age. But always the lethality of female doctors is lower than that of male doctors (3% and 13%, respectively).

Female doctors are certainly no different from other women, neither by resistance of the immune system, nor by hormonal levels and obviously by genetic or epigenetic expressions. Of course they have different lifestyles and they know how to take better care of their health and this certainly influences in part explaining this big difference. But a simpler explanation suggests that the lethality of women in the 50-year-old population has not been correctly assessed. The paucity of deceased female doctors and male doctors leads us to think that the contagion in the 50-year-old population was at least four times more widespread than what these numbers tell us, and probably much higher among women. This hypothesis is consistent with the estimate, confirmed by the May data in Italy and by many scientific papers, that the percentage of infected people who show mild or asymptomatic symptoms is around 80%. Unfortunately, these estimates are only available in aggregate form by age and gender. Equal lethality after 60, between male doctors and the general population suggests that the proportion of asymptomatic or pauci-symptomatic could drastically decrease with age, especially in males. This is consistent with the greater vulnerability of the male sex to disease, possibly also resulting from the levels of sex hormones and male habits and lifestyles.

This analysis took into consideration the data on the number of infections of health personnel and the general population for the various age groups published on the report of the Istituto Superiore di Sanità of 28/4/2020, while it made an estimate of the number of contagions between male and female doctors, considering the gender distribution of healthcare personnel in 2017, as described in the latest report published by the Ministry of Health. Unfortunately, these are outdated data and therefore the estimate made cannot be exact. Furthermore, we hypothesized that the contagion among healthcare workers is stator monitored more frequently that not in the general population, but unfortunately, the analysis of swabs for healthcare personnel is not currently available and it is desirable that a more detailed analysis be carried out thorough, that the commission Covid-19 of the Accademia dei Lincei is playing.

All this underlines the need and urgency to face data collection in a more analytical way, based on gender, age, type and qualification of the job, in order to develop the most appropriate strategies to face the second, perhaps inevitable , wave of contagions. Gender medicine can greatly enrich our knowledge and must no longer be neglected in public health management.

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