No evidence coronavirus vaccines affect fertility, experts reassure

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Watch: Do coronavirus vaccines affect fertility?

Experts have stressed there is no evidence the coronavirus vaccines affect fertility.

Since the infectious outbreak emerged at the end of 2019, an effective immunisation programme has been hailed as a route back to life as we once knew it.

The UK has three vaccines in its immunisation arsenal – Pfizer-BioNTech, University of Oxford-AstraZeneca and Moderna – all of which were subject to intense scrutiny in gold-standard clinical trials before being granted approval.

While the jabs have been shown to be safe, with the vast majority of side effects being mild and fleeting, social media is awash with unsubstantiated claims the vaccines may affect an individual's hopes of becoming a parent.

After analysing the jabs' roll-out in England, scientists from Imperial College London were reassured more than nine in 10 of the over 172,000 survey respondents have accepted or intended to accept the vaccine when called up.

Vaccine confidence was lower among the female respondents, however, with 90% wanting a jab, versus 93% of the males. The scientists put this down to "wider concerns about future fertility".

Read more: One coronavirus jab dose 80% effective at warding off severe disease in elderly

With more than 20 million people in the UK receiving their first vaccine dose to date, and all adults due to be offered a jab by 31 July, experts have stressed there is no evidence or theoretical plausibility the shots affect fertility.

This comes ahead of International Women's Day on 8 March, which aims to "assist women to be in a position of power to make informed decisions about their health".

Doctor drawing up Covid-19 vaccine from glass phial bottle and filling syringe injection for vaccination. Close up of hand wearing protective disposable gloves in lab and holding a bottle of vaccination drugs. Hand with blue surgical gloves taking sars-coV-2 vaccine dose from vial with syringe: prevention and immunization concept.
Coronavirus vaccines protect against severe disease called COVID-19. (Stock, Getty Images)

Infertility rumours have largely been directed towards the Pfizer-BioNTech and Moderna vaccines, the latter of which has not yet been rolled out in the UK.

These jabs are "RNA vaccines", made up of tiny fragments of the coronavirus' genetic code, surrounded by a bubble of fat.

After the vaccine is administered, it creates the coronavirus' spike protein, which the pathogen ordinarily uses to invade cells.

Being vaccinated causes the body to recognise the spike protein and make immune cells against it.

The Oxford-AstraZeneca vaccine is based on a common cold virus that infects chimpanzee. This virus has been altered so it does not infect people but has a bit of the coronavirus' genetic code added in.

Once inside the body, the spike protein is again produced.

Read more: One Pfizer coronavirus vaccine dose cuts asymptomatic infections

"We want to reassure women there is no evidence to suggest COVID-19 [the disease caused by the coronavirus] vaccines will affect fertility," Professor Lucy Chappell from the Royal College of Obstetricians and Gynaecologists told Yahoo UK.

"We're aware there are myths circulating about this, but claims of any effect of COVID-19 vaccination on fertility are speculative and not supported by any data.

"There is​ ​no biologically plausible mechanism by which current vaccines would cause any impact on women's fertility.

"The theory immunity to the spike protein could lead to fertility problems is not supported by any evidence.

"Most people who contract COVID-19 will develop antibody to the spike and there is no evidence of fertility problems in people who have already had COVID-19."

Other vaccines, like those against flu, are also known to have no impact on fertility.

What's more, the government's Joint Committee on Vaccination and Immunisation (JCVI) – which advises UK health departments – has said women who are trying to become pregnant do not need to delay conception after receiving their jab.

Britain's new Deputy Chief Medical Officer for England Jonathan Van-Tam speaks during a virtual press conference inside 10 Downing Street in central London on March 1, 2021, to give an update on the coronavirus covid-19 pandemic. - Britain on Monday appealed for a person infected with a powerful Covid-19 strain from Brazil to come forward, as experts fretted about its impact on new vaccines. (Photo by Ian Vogler / POOL / AFP) (Photo by IAN VOGLER/POOL/AFP via Getty Images)
Professor Jonathan Van-Tam, England's deputy chief medical officer, has dismissed vaccine-related infertility rumours as 'nonsense'. He is pictured during a 10 Downing Street press conference on 1 March 2021. (Getty Images)

RNA vaccines are a new phenomenon, leaving some concerned long-term safety data are unknown.

The technology has been in development for more than three decades, however, with the jabs' effects being studied in laboratories.

A December 2020 Facebook post read: "The [coronavirus] vaccine contains a spike protein called syncytin-1, vital for the formation of human placenta in women.

"If the vaccine works so we form an immune response AGAINST the spike protein, we are also training the female body to attack syncytin-1, which could lead to infertility in women of an unspecified duration!"

Speaking at the Progress Educational Trust's event The COVID vaccine: a short in the arm for fertility treatment?, Professor Jason Kasraie from the Association of Reproductive and Clinical Scientists said: "This [post] is based around the spike protein of the virus being [supposedly] similar to syncytin-1, which is a human placental protein.

"Obviously, this just isn't correct. There are no real similarities between these two proteins.

"The theory is, if you have the vaccine, you become infertile, because your immune system will fight against syncytin-1 and your own placenta – no evidence for this, it simply isn't true.

"This is a theory that is easy to prove to be false, but it's on social media still and people are still raising concerns about it."

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The vaccines are injected into an individual's muscle, where the RNA particles and its fat bubble are said to disintegrate within several days at most.

"They do not travel into the rest of the body," said Dr Sigal Klipstein, from the American Society for Reproductive Medicine's COVID-19 task force.

"According to the mechanism of action [of the vaccines], they should not impact fertility – whether that be egg or sperm, fertilisation, implantation."

Read more: I felt guilty for having the coronavirus vaccine

The JCVI does not recommend pregnant women have a coronavirus vaccine "routinely", however, it should be "considered" if ha woman's "infection [risk] is high and cannot be avoided, or where the woman has underlying conditions that put them at very high risk of serious complications".

Pregnant women are never enrolled in clinical trials testing a new drug or jab until a sufficient level of safety data is collected.

"It is a difficult message to get across," said Professor Helen Ward, from Imperial College London.

"People hear it and think 'maybe it's [the vaccine] not safe', [which leads to] fears about future fertility."

Professor Jonathan Van-Tam has also weighed in on the issue.

When asked on Good Morning Britain whether a woman who is considering becoming pregnant in the next year should defer a vaccine, England's deputy chief medical officer dismissed infertility concerns as "nonsense".

"There's just no evidence at all that there are any issues in relation to planning a family or fertility," he said.

"If you're called, my advice would be to get on and take the vaccine."

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