Is there any scientific basis for the new coronavirus to cause male infertility?

New coronaviruses are detected in the semen of both diseaseand and post-disease male patients, according to new studies. Does it affect reproductive function and should sexual contact spread? Over the past few months, several data suggest that the new corona virus seems to be more “abuse” of men. In addition to the overall number of diagnoses and fatality rates are higher than in women, more recent studies have shown that new coronaviruses have been detected in the semen of both patients in disease and in the aftermath of the disease.

Is there any scientific basis for the new coronavirus to cause male infertility?

What it means to detect a new coronavirus in semen

Author . . . Xu Sijia, School of Medicine, Kyoto University, Japan

Edited . . . Long Hao

How does the new coronavirus affect the male reproductive system? Does infection with the new coronavirus cause male infertility?

Respiratory virus infection reproductive organs?

The new coronavirus is a respiratory virus, the name classification is based on the virus’s main transmission route and the most obvious symptoms. However, the pathogenic behavior of viruses is often complex.

In terms of infection mechanism, the new coronavirus is through its surface protrusion (echidna protein) and human cell surface a protein called ACE2, to anchor and invade human cells. In February, scientists at the National Institutes of Health identified male testicular cells that also have a rich ace2 expression, which contains a lot of ACE2 protein, suggesting they may also be potential targets for new coronavirus infections.

Is there any scientific basis for the new coronavirus to cause male infertility?

The echinoprotein steamed by the echidna protein on the surface of the virus, which binds to enter the body’s cells. From the network

On May 7, a small study from china detected the new coronavirus directly in the semen samples of the subjects. A total of 38 subjects were surveyed, of whom 4 were positive for viral nucleic acid in semen samples of 15 men infected with acute stage, and 2 of the 23 men in the recovery period were positive for viral nucleic acid, with a detection rate of 26.7% and 8.7%, respectively.

The concern is, can viral infections affect fertility function?

Affects reproductive function? No direct research has been made.

Earlier, Professor Zhang Ming’s team at Wuhan University’s Zhongnan Hospital published a study showing that new coronavirus infection sparks changes in the sexual function. They tested the subjects for sex hormone levels and found that serum progesterone (LH) levels were significantly higher in 81 men of reproductive age compared to 100 healthy men.

Serum progesterone is a gonadotropin that promotes the synthesis of testosterone, an important male hormone. Testosterone is closely related to the maturation of male sexual organs, the maintenance of normal libido and erectile function. In the study, the patient’s serum testosterone levels were not significantly reduced, but the potential low testosterone levels could not be ignored, given the potential for compensation effects that may have been the incremental release of upstream LH hormones.

However, the study is small and has not yet been peer-reviewed, so changes in sex hormone levels are now only indirect evidence that the new coronavirus attacks testicular function. The most direct way to assess male reproductive function is still semen examination.

Semen quality is a direct reflection of male reproductive function, the evaluation criteria can not be based on ejaculation, semen texture and other visual impressions, but also to investigate sperm count, sperm vitality, morphology, serum and sperm plasma in the content of immune substances and other factors. These indicators need to be tested and evaluated in formal medical facilities.

The above suggested that the patient’s semen virus detection studies, did not involve sperm count and activity evaluation, there is no long-term tracking of positive results of cases, so the new coronavirus in the final survival of semen for how long is not known.

Blood testicles barrier allows viruses to take advantage of

There is a natural protective structure in the male testicles, called the “blood testicles barrier.” It is a delicate immune barrier to ensure the smooth growth of sperm.

We know that both male sperm and female eggs have only half the number of chromosomes in normal somatic cells, and that they combine to form fertilized eggs to have a normal number of chromosomes. To prevent the body’s immune cells from mistaking sperm for enemies for attack, a “blood testicle barrier” is set up in the male testicles.

The blood testicles barrier separates the progenitor cells that are adjacent to the blood vessels and the sperm cells that have begun to differentiate into mature sperm and have a decreasing number of internal chromosomes, so that the immune cells patrolled in the blood do not attack differentiated or mature sperm.

The “blood testicular barrier” is dense, and in addition to immune cells, most harmful substances (including drugs) and larger bacteria are also difficult to get into the side of mature sperm. But many viruses prefer to know hard, can cross the blood testicles barrier, infect the testicular tissue, when immune cells often have to watch the fire across the shore.

Is there any scientific basis for the new coronavirus to cause male infertility?

Testicles (left) – raw sperm tube (flesh)-blood testicular barrier (red dotted line), immune cells are blocked out of the barrier (bottom right) Author’s picture

Because the “blood testicular barrier” is immune from attacks by the immune system, the virus is likely to survive and replicate over the long term, which in turn can spread along the reproductive tract and spread to sexual partners through sexual contact.

Multiple viruses “prefer” to infect testicles

In fact, pathogens attack ingress on male testes is not new, bacteria and viruses can cause testicularitis. But the testicles themselves are rarely bacterial, usually bacteria invade the adjacent testicles and then affect the testes.

Because the testes are rich in blood and lymphatic fluid, coupled with the presence of blood testicular barriers, the resistance to bacterial infections is stronger.

However, the blood testicular barrier does not completely isolate the virus, so the testes are often the main target of the virus.

When the virus breaks through the blood testicles barrier and reaches the other side of the immune cell deficiency, it is as if it has found a long-standing “safe house”.

Many of these cunning viruses are familiar to us, such as:

Mumps, a respiratory virus transmitted by airborne droplets. The mumps caused by it is also commonly known as “mumps” and “big mouth”. The most common effects are in children 5-15 years old and can also infect adults. Although rarely life-threatening, complications are even more troubling, including testicularitis. The incidence of testicularitis in male patients after youth development can be as high as 35%, mostly on one side. If both testicles are affected, it may cause infertility in adulthood.

Is there any scientific basis for the new coronavirus to cause male infertility?

Testicular inflammation caused by mumps virus is often accompanied by severe pain . . . From the network

HIV ( HIV ) , originally is to escape and destroy the body’s immune system master , testicles is HIV in the body of one of the ” safe warehouse. The pathway of effective transmission of HIV through semen has been proven.

The Zika virus is a virus transmitted through insects. There is clear evidence that the Zika virus directly damages the reproductive system of male mice. The testicles of infected malemice decreased significantly, and sperm count and testosterone levels dropped significantly, reducing the chances of pregnancy in female mice by about four times. The Zika virus can also pass through the blood testicles barrier and enter semen for months, so it can also be transmitted through sexual contact. Infected pregnant women give birth to babies with microcephaly.

In addition, in addition to the direct damage of the virus, symptoms such as fever caused by certain infections (e.g. influenza) may also reduce semen and sperm production and reduce sperm vitality. But this effect is usually temporary and will ease as the condition improves.

Prepare for pregnancy should pay due attention to sexual contact transmission

Finally, it is important to note that:

There is no direct evidence that the new coronavirus causes male infertility.

According to the World Health Organization definition, the couple does not take any contraceptive methods to have sex for more than one year, due to male factors caused by the woman’s failure to conceive can be judged male infertility. In real life, infertility can be caused by both men and women for a variety of reasons: including the quality of reproductive cells, the degree of access to the reproductive tract, sex life, personal physique and other factors can affect the results. In the course of actual pregnancy preparation, the individual situation and the examination results shall prevail.

Whether or not the sex life spreads the virus depends on the “viral load”

Whether it is saliva, aerosols, surfaces with viruses, or semen, the virus is bound to spread without contact. The key depends on the “viral load” (i.e. the virus concentration) in these vectors, i.e. whether the virus will spread through sexual contact, depending on the amount of virus copied per milliliter of semen.

Reasonable reference to the results of the study, pay attention to pregnancy protection

At present, there are few studies through expert deliberations, and the scale of the study is more limited. But some of the findings have also been reflected in previous studies of other viruses: for example, testicular cells have susceptibility to the virus, infection can cause changes in sex hormone levels, viruses in semen and the duration of unknown. These are worthy of the intention to prepare for pregnancy of the child-bearing population attention, strengthen the necessary protection.

Try to avoid travel to the epidemic-sustaining areas during pregnancy, for people with a history of infection or still in the recovery stage, should be alert to the possibility of sexual contact transmission, and actively improve nucleic acid review and fertility-related indicators of testing.


Li, D., Jin, M., Bao, P., Zhao, W. and Zhang, S. Clinical Features and Results of Semen TestS Men With CoronaVirus Disease 2019. JAMA Netw. Open 3, e208292 (2020).

Wang, Z. and Xu, X. scRNA-seq Profiling of Human Tests Reveals the Ness of the ACE2 E. Cells 9, (2020).