covid: vaccine not affect sperms

 

One reason for Covid vaccine hesitancy is the concern about infertility. A recent small study confirmed that there was no adverse effect of the mRNA vaccines on sperm parameters (see covid mRNA vaccine not affect sperm JAMA2021 in dropbox, or doi:10.1001/jama.2021.9976) 

 

Details:

-- 45 healthy men between the ages of 18 and 50 volunteered in a single center, prospective study at the University of Miami between December 2020 and January 2021

    -- these men were recruited through fliers at the University and internal emails

-- 21 men received the Pfizer vaccine and 24 the Moderna one

-- semen samples were provided after 2-7 days prior to their 1^st vaccine dose and approximately 7 days after the 2^nd dose

    -- median sexual abstinence 2.8 days (2-3) before baseline and 3 days (3-4) before the follow-up samples

--follow-up samples were a mean of 70 days after the 2^nd dose

-- those with baseline oligospermia  (sperm count <15 million/ml) were included

    -- 8 of the 45 men were oligospermic before vaccine, median sperm concentration 8.5 million/ml

 

Results:

-- sperm volume

    -- baseline 2.2 mL (1.5-2.8), follow-up 2.7 mL (1.8-3.6), p=0.01

-- sperm concentration:

    -- baseline 26 million/ml (19.5-34), follow-up 30 million/ml (21.5-40.5), p=0.02

-- sperm motility:

    -- baseline 58% (52.5-65), follow-up 65% (58-70), p=0.001

-- total motile sperm count:

    -- baseline 36 million (18-51), follow-up 44 million (27.5-98), p=0.001

-- those initially oligospermic: 7 of the 8 had increased sperm concentration to the normal range at follow-up. No man became oligospermic after the vaccine

 

Commentary:

-- there were actually statistically significant increases in all of these sperm parameters postvaccination (though overlapping confidence intervals)

-- men who had pre-existing oligospermia did not have further decline in their sperm parameters

-- these results are not so surprising, given that the mRNA vaccines (and others) do not contain the live virus (unlike the vaccines, Covid-19 infection itself has been associated with adverse sperm parameters: a study of 30 men 11-64 days after being PCR-positive for SARS-CoV-2 infection found that total sperm number was decreased to 12.5 million/ml (vs 21.5 million/ml in those PCR negative); 5 of these men completed a follow-up sperm analysis and had a median of 18 million/ml; sperm motility was not assessed because these were samples that were shipped and not fresh. but, in 16 samples analyzed, there was no PCR-detected RNA in the semen (see covid sperm number dec WJMH2021 in dropbox, or doi.10.5534/wjmh.200192)

 

Limitations:

-- though these results did show increased sperm parameters post-vaccination, these were within the boundaries of normal variation and the confidence intervals noted could reflect individual variation

    -- there may have been more ejaculation abstinence during the time of the vaccinations, leading to higher sperm parameters (patients did state there was a slight delay during the course of vaccination, but unclear what the reliability was)

    -- or, there are just such wide range of sperm values that the repeats just represented regression to the mean (especially in those initially oligospermic, who largely normalized their values)

-- this was a small study of young healthy men, with short follow-up, and results may be not generalizable to the broader, larger population

    -- and, the study included participants recruited through the University, also a select group and healthier than the overall population

-- and the sperm parameters measured are a surrogate marker and may not predict actual clinical fertility. actually it is pretty daunting to conduct a reasonably definitive fertility study, either an RCT (no chance there...) or perhaps a large observational study of people attempting pregnancy who did vs didn't get vaccinated

    -- this study would need to be large enough to compensate for the fact that there are large and important female infertility factors (only about 25% of infertility is pretty clearly related to male factors)...

 

So, a few points:

-- there had been an absence of information from the 2 mRNA vaccines on reproductive toxicity in the clinical trials, so this trial provides useful reassuring information

-- we as a society need all the help we can get to encourage people to get vaccinated. To the extent that there is vaccine hesitancy related to the question of male infertility, this study provides significant reassurance (and, reinforces the likelihood that non-live virus vaccines are unlikely to affect fertility)

 

geoff

 

If you would like to be on the regular email list for upcoming blogs, please contact me at gmodest@uphams.org 

to get access to all of the blogs (2 options):

1. go to http://gmodestmedblogs.blogspot.com/ to see them in reverse chronological order

2. click on 3 parallel lines top left, if you want to see blogs by category, then click on "labels" and choose a category​

3. or you can just click on the magnifying glass on top right, then  type in a name in the search box and get all the blogs with that name in them

 

or: go to https://www.bucommunitymedicine.org/ , a website from the Community Medicine section at Boston Medical Center.  This site does have a very searchable and accessible list of my blogs (though there have been a few that did not upload over the last year or two). but overall it is much easier to view blogs and displays more at a time.

 

 

please feel free to circulate this to others. also, if you send me their emails, i can add them to the list