London, Jun 18 (IANS): Taking Pfizer or Moderna Covid vaccine shots do not lower sperm counts in men, claimed a study.

Researchers at the University of Miami studied sperm counts in men who had recently been vaccinated, and compared the results to their sperm count before being vaccinated, the Daily Mail reported.

The findings published in the journal JAMA showed that the average men increased sperm count by 22 per cent with the largest increase in sperm count at 90 per cent.

The increases may not be because of the vaccine, though, as they fall within normal fluctuations of sperm counts, the researchers said.

Many false claims about the vaccines and their effects on sperm count and fertility have surfaced on social media in recent months.

The study did not find any sperm count reduction in men who had received either one or two doses of the Pfizer-BioNTech or Moderna coronavirus vaccine, and the final mean and median sperm counts even increased.

The largest decrease in sperm count of any man in the study was only 20 per cent, the report said.

For the study, the team recruited 45 men aged 18 to 50 years old, all of whom had no previously known case of Covid-19 and did not exhibit symptoms of the virus.

After two to seven days of abstinence, and before receiving their first vaccine dose, a semen analysis was performed on the respondents of the study.

Their sperm counts were analysed once again 70 days after they received the second dose of either mRNA vaccine.

The median sperm count increased from 26 million cells per milliliter of fluid (m/ml) to 30 m/ml, a 15 per cent increase.

Meanwhile, average sperm count increased from 36 m/ml to 44 m/ml, a 22 per cent increase.

Sperm volume and sperm motility also significantly increased during this period, the report said.