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Men infected with even mild COVID cases experience long-term decline in semen quality

Researchers have discovered that even mild cases of COVID-19 can affect a man’s semen quality months after infection. This revelation was part of a study presented at the 39th annual meeting of the European Society of Human Reproduction and Embryology (ESHRE) on Monday.

The study found that men who had mild COVID-19 infections had fewer and less active sperm cells. This continued over three months after their recovery. These findings were surprising since sperm cells should regenerate within this period.

Professor Rocio Núñez-Calonge, a scientific advisor at UR International Group at the Scientific Reproduction Unit in Madrid, led the research team.

She expressed her team’s surprise over these findings. She stated, “We assumed that semen quality would improve once new sperm were being generated, but this was not the case. We do not know how long it might take for semen quality to be restored and it may be the case that COVID has caused permanent damage, even in men who suffered only a mild infection.”

How the team studied semen quality after COVID-19

Núñez-Calonge and her team started the study after noticing that some men who attended reproductive clinics in Spain had worse semen quality after recovering from mild COVID-19 infections.

Given that it takes about 78 days to produce new sperm, the team found it appropriate to evaluate semen quality at least three months after recovery.

For their research, they recruited 45 men from six reproductive clinics in Spain between February 2020 and October 2022. All participants had recovered from mild COVID-19 infections. The team had access to the men’s semen samples taken before and after their infections.

The scientists made alarming discoveries when they analyzed the samples. They discovered that every aspect of semen quality was impacted, even after an average of 100 days post-infection.

Semen volume was down by 20%, sperm concentration had fallen by 26.5%, total sperm count had reduced by 37.5%, and total motility was down 9.1%. The number of live sperm had also decreased by 5%.

The connection between COVID-19 and semen quality

The researchers’ findings suggest that mild COVID-19 infections could cause permanent damage to semen quality. This is a concern that Núñez-Calonge wants clinicians to take seriously.

She noted, “It is particularly interesting that this decrease in semen quality occurs in patients with mild COVID infection, which means that the virus can affect male fertility without the men showing any clinical symptoms of the disease.”

Núñez-Calonge and her team are not yet sure why COVID-19 affects sperm cells in this way. However, they suspect that inflammation and damage to the immune system could be factors.

These are often seen in patients with long COVID. They plan to continue studying the participants to track semen quality and hormonal status over time.

Commenting on the study, the chair of ESHRE, Professor Carlos Calhaz-Jorge, not involved in the research, said, “This is interesting research by Prof. Núñez-Calonge and her colleagues and shows the importance of long-term follow-up of fertility patients after a COVID infection, even if it’s a mild infection. However, it’s important to note that the semen quality in these patients after a COVID infection is still within the World Health Organization’s criteria for ‘normal’ semen and sperm. So, it is unclear whether these reductions in semen quality after a COVID infection translate into impaired fertility and this should be the subject of further research.”

The findings of this study have opened up a new area of COVID-19 research. It could impact our understanding of the virus’s long-term effects on human fertility.

It underlines the importance of further studies to determine whether these changes in semen quality after a COVID-19 infection could indeed lead to impaired fertility.

Tell me more about long-term COVID-19 symptoms

There are many long-term symptoms of COVID-19, often referred to as “long COVID.” These can affect patients weeks or even months after they recover from the acute phase of the illness.

Researchers are continuing to study long COVID, but they have already identified several common symptoms.


Many individuals with long COVID report prolonged fatigue that doesn’t improve with rest. This isn’t just a general tiredness but a debilitating exhaustion that can impact daily activities.

Shortness of breath

Some individuals experience continued difficulty with breathing or shortness of breath long after their initial recovery.

Cognitive difficulties

Often referred to as “brain fog,” these symptoms can include difficulties with concentration and memory, confusion, and problems with sleep.

Mental health problems

Anxiety, depression, and other mental health disorders can develop or worsen in people with long COVID.

Heart issues

Some individuals may experience symptoms such as palpitations or fast-beating heart, and in some severe cases, inflammation of the heart muscle.


This can be in the form of headaches, joint pain, or muscle aches that persist for extended periods.

Long-term loss of taste and smell

While loss of taste and smell is a well-known symptom of acute COVID-19, some individuals find these senses do not return to normal for weeks or months.

Gastrointestinal issues

People have reported persistent symptoms such as diarrhea, abdominal pain, loss of appetite, and nausea.

Other symptoms

These can include fever, cough, and skin rashes.

Factors such as the severity of the initial infection, the patient’s age, and pre-existing health conditions can influence who is likely to experience long COVID.

However, even people with mild cases of COVID-19 can experience these long-term symptoms. Also worth noting is that we need more research to fully understand the virus’s long-term impact, so this list of potential long-term symptoms isn’t exhaustive.

Please consult with a healthcare professional if you or someone you know is experiencing any long-term symptoms following a COVID-19 infection. They can provide the most up-to-date and relevant advice and treatments.

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