Several countries have observed changes in birth rate that have a correlation in time with the pandemic and the vaccination roll-out. Swissmedic has recently received enquiries from the public and media representatives concerning a possible link between COVID-19 vaccination and fertility. From a scientific perspective, neither the published literature nor global market surveillance yield any indication that mRNA vaccines could impair human fertility. Furthermore, Swissmedic has not received any safety signals from within Switzerland.
Swissmedic and ten partner authorities have reviewed indications of a possible link between fertility and Covid 19 vaccination. Investigations have included countries with significantly higher vaccination coverage than Switzerland. The partner medicinal product regulatory authorities are responsible for a population of around 800 million people. None of the countries in question have seen or evaluated a signal related to COVID-19 vaccination and fertility.
Different fertility rate trends from country to country
A working paper by Germany’s Federal Institute for Population Research cites both the health crisis and associated economic uncertainty as the cause of the lower birth rate. Several countries – Spain, Japan, United Kingdom and the USA – noted a significant decline in fertility rates just nine months after the start of the pandemic (in other words, before vaccination roll-out started). By contrast, Sweden and the German-speaking countries recorded an initial rise in fertility rates during 2021 followed by a sharp decline at the start of 2022. These countries are discussing the possibility that the decline is due to couples postponing having children because they are worried that vaccination may have a detrimental impact on their fertility. The originally cautious official recommendations regarding vaccination for pregnant women may have contributed to this.
Fertility rate trends vary greatly from country to country, and it is therefore virtually impossible to demonstrate a causal relationship between vaccination and fertility.
Possible link to COVID-19 disease
However, certain studies indicate that male fertility can be temporarily reduced not by vaccination but by COVID-19 infection. There is evidence of reduced sperm production, erectile dysfunction or testosterone deficiency in some men who had been infected with coronavirus. The post-infection likelihood of pregnancy dropped swiftly in some cases. It took at least 60 days for these men’s fertility to reach the same level as that of men who had not been infected.
No safety signals from Switzerland
Since the start of the pandemic, Swissmedic has published 27 updates on reports of suspected adverse reactions to COVID-19 vaccines in Switzerland. The available data and analyses provide no statistical evidence of a causal relationship between COVID-19 vaccination and the decline in births. Neither ongoing authorisation studies nor global market surveillance have given Swissmedic any scientific indicators that mRNA vaccines to prevent COVID-19 could impair human fertility.