The COVID-19 pandemic not only altered our daily lives but also prompted questions about reproductive health. In particular, the debate over “unvaccinated vs. vaccinated sperm” is clouded by myth. What does the scientific evidence actually say? In this article, we’ll set the record straight, dispel misconceptions, and explain which factors truly influence sperm quality.
Why Sperm Quality Matters: The Basics
Sperm are specialised cells that deliver the male genetic material to the egg. Each sperm cell plays a crucial role, supplying 50% of the genetic material for new life.
Sperm quality is assessed according to four key parameters:
- Concentration: Number of sperm per millilitre of ejaculate
- Motility: Movement and forward progression
- Morphology: Percentage of normally shaped sperm
- DNA integrity: Intactness of the genetic material
These measures are sensitive to illness, lifestyle, and environmental factors. But does the COVID-19 vaccine affect them?
Scientific Evidence on COVID-19 Vaccination and Sperm Quality
Researchers worldwide have investigated whether mRNA and vector vaccines alter sperm parameters. The unanimous finding: there is no evidence of lasting impairment.
A JAMA study (Gonzalez et al., 2021) compared sperm parameters in 45 healthy men before and after mRNA vaccination and found no significant differences in concentration, motility, or morphology (Gonzalez DC et al. 2021).
A systematic review of 24 studies (Chen et al., 2023) confirmed that neither mRNA nor vector vaccines have clinically relevant effects on sperm count, motility, or DNA integrity. Read more
COVID-19 Infection vs. Vaccination: Risk and Protection
A cohort study showed that SARS-CoV-2 infection can temporarily reduce all sperm parameters and cause DNA fragmentation, whereas vaccination has no such effects (Yuan et al., 2025) View the study.
The WHO and UK Health Security Agency therefore recommend vaccination not only to prevent COVID-19 but also to protect fertility. CDC: COVID-19 Vaccination for Those Planning a Pregnancy
Long-Term Studies and Emerging COVID-19 Vaccines
Alongside the evaluated mRNA and vector vaccines, several long-term studies—such as those in Canada and Japan—are tracking participants over 12 months, collecting regular samples and health data to rule out very rare effects.
Additionally, protein-based vaccines (e.g. Novavax) and other platforms are under review. Early immunogenicity data show high efficacy with mild side effects. Since these vaccines do not enter gonadal tissue, experts do not anticipate any impact on sperm quality. Publication of detailed results is expected in the coming months.
Lifestyle and Environment: Keys to Healthy Sperm Quality
To support fertility, consider the following:
- Nutrition: Plenty of fruit, vegetables and omega-3 fatty acids; limit alcohol and avoid smoking
- Exercise & Weight: Regular physical activity and maintaining a healthy BMI
- Stress Management: Techniques such as yoga or meditation
- Environment: Reduce exposure to pesticides, heavy metals and industrial chemicals
Outlook: Ongoing Monitoring of Sperm Quality
Regulatory bodies like the WHO and independent researchers continue to monitor for any late-onset effects. To date, there is no indication of long-term harm, as vaccines do not alter germ cells.
Practical Tips: Semen Analysis & Fertility Check
If you wish to assess your fertility comprehensively, consider a semen analysis approximately three months after completing your vaccination course. Since sperm maturation takes around 72–90 days, this timing provides an accurate picture of current sperm quality.
- Preparation: Abstain from ejaculation for 2–7 days before sample collection.
- Lab Selection: Choose an accredited andrology or urology centre for reliable results.
- Regular Monitoring: If facing fertility challenges, repeat testing every six months.
- Consultation: A urologist or andrologist can interpret results and recommend interventions such as lifestyle modification or hormone therapy.
References & Further Reading
- Gonzalez DC et al. Sperm Parameters Before and After COVID-19 mRNA Vaccination. JAMA 2021.
- Chen YX et al. Effects of SARS-CoV-2 Vaccines on Sperm Quality: Systematic Review. JMIR Public Health Surveill 2023.
- Yuan L et al. COVID-19 Infection Was Associated with Poor Sperm Quality. Scientific Reports 2025.
- CDC: COVID-19 Vaccination for Those Planning a Pregnancy. 2024.
Conclusion
The scientific consensus confirms that COVID-19 vaccines do not cause lasting impairment of sperm quality. A healthy lifestyle, effective stress management and regular check-ups remain the most important factors. For personalised advice, consult a urologist or andrologist.