For weeks now, women have watched as several countries – including Italy, France and Spain – halted or restricted the use of the Oxford-AstraZeneca Covid-19 vaccine, due to a small number of rare blood clots found in recipients. Now, the UK government is offering under-30s an alternative vaccine (such as Pfizer or Moderna) in light of a possible link. The move has left many women questioning why there has never been public concern around the increased risk of potential blood clots women face every day, simply by taking certain contraceptives.
“I’ve had a blood clot caused by medication that women are prescribed every single day without a care in the world. Let’s make sure we are careful to properly understand the rare nature of what is being reported,” tweeted Labour MP Jess Phillips. Contraceptives such as vaginal rings and patches and certain pills contain forms of progesterone and oestrogen hormones, and have been associated with an increased risk of clots. Statistics obtained by the Guardian found that 9 in 10 women in England are prescribed the pill after discussing contraceptive methods with their GP. In 2019, UN figures found that an estimated 842 million people use hormonal contraceptives.
Amongst the tweets, a piece of thorough research carried out by Glasgow GP Margaret McCartney, author of The State Of Medicine, is being shared. She found that the estimated incidence of a blood clot with the combined oral contraceptive pill is about five per 10,000 women per year — a risk of one in 2,000, or 0.05 per cent. Based on the numbers as they stand, this represents a far higher risk of developing a blood clot in comparison to that associated with the vaccine. Still, Dr McCartney says it’s important that there is honesty and transparency about potential side effects to the vaccine, “even if rare”. “Trials of 40 and 50,000 people – as were done to prove the vaccines work – were essential, but of course, are not big enough to pick up very, very rare side effects that really need millions of people to be revealed,” she tells British Vogue.
At the time of writing and according to the British Medical Journal, there have been 79 reported UK cases of blood clotting in people after they were inoculated with the AstraZeneca vaccine, with 19 deaths, out of 20 million people. “Based on numbers released by Medicines and Healthcare Products Regulatory Agency (MHRA) on 7 April, an average of 4 per 1,000,000 people who received the AstraZeneca vaccine developed a blood clot,” Dr Lori-Ann Linkins, an associate Professor of Medicine at McMaster University and thrombosis consultant, tells British Vogue. “So, based on these numbers, the risk of developing a blood clot while taking the pill is about 100 times higher than with the vaccine. Yet, millions of women across the world accept this risk because the benefits of preventing unwanted pregnancy or controlling heavy periods greatly outweigh this very small risk of blood clots.”
Both Dr Linkins and Dr McCartney are keen to put this risk into context for everyone right now – especially as the recent move made by the government has the potential to increase vaccine hesitancy. “There is a background rate of blood clots happening all the time, without vaccinations or medication that we know increases the risk,” Dr McCartney explains. “For 10,000 women using the combined contraceptive pill, there are about 5 to 17 extra cases of blood clots per year, depending on pill type. For pregnancy, it’s much higher – 10 to 20 cases per 10,000 per pregnancy and up to six weeks after delivery.”
However, some women think drawing a comparison between the Covid-19 vaccine and oral contraception is unhelpful. “These aren’t directly comparable – the risk of the vaccine is one-off, whereas being on the pill and being pregnant is, of course longer term, and the condition of concern (Cerebral Venous Sinus Thrombosis) has many differences between the kinds of clots [the vaccine] could cause,” says McCartney in agreement. “But it gives a sense of what kind of risks everyday situations give us.”
“A comparison between clotting risk with the pill and vaccine has limitations, because the clotting risk with the pill is spread over several years while the risk of clotting with the vaccine is limited to a few weeks,” Dr Linkins says. “But to be fair, we also have to consider the risk of complications due to becoming infected with Covid-19, which include a risk of blood clots that is as high as 1 in 20 (in patients admitted to the ICU), long-term neurological and cardiovascular problems (even in young people), and death.” However, the point many women are making is that they’ve had to accept the daily worry of a risk of developing a blood clot while taking the pill – not just during the ongoing pandemic. It's time for better access to consultations about different forms of contraception.
Women are also questioning whether the risk to women in their 30s who are taking the pill and will be getting the vaccine has been considered. “Okay, but what about women in their 30s taking the contraceptive pill? Do we even have the safety data here? tweeted Caroline Criado-Perez, author of Invisible Women: Exposing Data Bias In A World Designed For Men. She’s not the only one asking the question either. “Miserably fitting that the antidote to a virus that has hurt women disproportionately because policy-makers don’t consider them has a. sparked concern over blood clots 60 years after the pill first dished out to women and b. not been reviewed for risk to women taking the pill,” tweeted Sophie Walker, feminist and author of Five Rules for Rebellion: Let’s Change the World Ourselves. “if anyone can find evidence of b. I would love to see it – haven’t been able to find anything so far.”
The experts Vogue spoke to acknowledge that information in this area is scarce, but they do have some reassurance for women who may be worried. “We do not know if women who are taking the pill are at higher risk for blood clotting if given the AstraZeneca vaccine,” says Dr Linkins. “So far, the blood clots that happen after taking the vaccine are not typical blood clots. They are triggered by the immune system, not the clotting system like the blood clots with the pill. For this reason, I am encouraging all of my patients with a history of blood clotting to get the first Covid-19 vaccine offered to them.” Dr McCartney anticipates that further information in this area will be forthcoming soon. But in the interim, like Dr Linkins, she wouldn’t hestitate – “for myself or any member of my family” – to say yes to the AstraZeneca vaccine.
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