No adverse effect of Pfizer and Moderns vaccine on sperm Parameters: JAMA

The study is published in the JAMA Network.

Two mRNA vaccines, BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna), received Emergency Use Authorization from the US Food and Drug Administration. Despite high efficacy and few adverse events found in clinical trials, only 56% of individuals in the US reported wanting to receive the vaccine.

One of the reasons for vaccine hesitancy is the potential negative effect on fertility. Because reproductive toxicity was not evaluated in the clinical trials and SARS-CoV-2 has been associated with decreases in sperm parameters, Daniel C. Gonzalez and colleagues from the Department of Urology, University of Miami, Miami, Florida carried out the present study to assess the sperm parameters before and after mRNA vaccine administration.

Men aged 18 to 50 years scheduled for mRNA COVID-19 vaccine were prescreened to ensure they had no underlying fertility issues. Those with COVID-19 symptoms or a positive test result within 90 days were excluded.

Participants provided a semen sample after 2 to 7 days of abstinence, prior to receiving the first vaccine dose and approximately 70 days after the second. Semen analyses were performed by trained andrologists per World Health Organization guidelines and included semen volume, sperm concentration, sperm motility, and total motile sperm count (TMSC).

Individuals with oligospermia (sperm concentration <15 million/mL) were included. After calculating data distribution on normality test, medians and interquartile ranges (IQRs) were reported for all variables.

Wilcoxon rank sum test was used to compare pre- and postvaccination semen parameters. Change in TMSC is presented graphically. Statistical analysis was performed with SPSS version 24 (IBM). A 2-tailed P value less than .05 was considered statistically significant.

The following findings were highlighted-

a. Of the 45 men, 21 (46.7%) received BNT162b2 and 24 (53.3%) received mRNA-1273.

b. Baseline sperm concentration and TMSC were 26 million/mL (IQR, 19.5-34) and 36 million (IQR, 18-51), respectively.

c. After the second vaccine dose, the median sperm concentration significantly increased to 30 million/mL (IQR, 21.5-40.5; P = .02) and the median TMSC to 44 million (IQR, 27.5-98; P = .001).

d. Semen volume and sperm motility also significantly increased.

e. Eight of the 45 men were oligospermic before the vaccine (median concentration, 8.5 million/mL [IQR, 5.1-12]).

f. Of these 8, 7 men had increased sperm concentration to normozoospermic range at follow-up (median concentration, 22 million/mL [IQR, 17-25.5]), and 1 man remained oligospermic.

g. No man became azoospermic after the vaccine.

Therefore, the authors concluded that "there were no significant decreases in any sperm parameter after 2 doses of a COVID-19 mRNA vaccine."