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The rollout of the Johnson & Johnson coronavirus vaccine is to be halted in Europe as an investigation is carried out into rare blood clots that have been reported in some recipients of the jab.
It comes as the Food and Drug Administration announced it was recommending a pause in the use of the vaccine in America “out of an abundance of caution” after detecting six cases of clotting. More than 6.8 million doses have been administered in the US so far.
With scientists beginning to speculate that the single-dose vaccine may be generating the same rare side effects as the Oxford-AstraZeneca candidate, one UK official suggested that the Johnson & Johnson jab could be restricted for use in older age groups only – if and when it is approved by Britain’s medicines regulator.
The Joint Committee on Vaccination and Immunisation (JCVI) has already advised that people under 30 be offered an alternative to the AstraZeneca vaccine, which, like the Johnson & Johnson jab, has been linked to clots in the brain and low levels of blood platelets seen in some patients.
Britain has ordered 30 million doses of the vaccine, to be manufactured by Johnson & Johnson’s pharmaceutical arm Janssen, with the Medicines and Healthcare products Regulatory Agency (MHRA) currently reviewing the jab for approval in the UK.
Professor Anthony Harnden, deputy chair of the JCVI, said any new safety data that emerges relating to the Johnson & Johnson vaccine and the rare blood clots would be scrutinised and “carefully reviewed” by the regulators.
“Depending on outcomes of any review, there may be implications for the recommendation of the Janssen vaccine in the younger age groups in the UK where the risk from severe Covid is much less than in older age groups and in those with underlying illnesses,” he added.
Both vaccines, along with the Russian Sputnik jab, use a modified adenovirus vector to carry genetic instructions into the body to generate an immune response against Covid-19. Some experts have speculated that this delivery mechanism could be triggering the rare reaction seen in a very small proportion of individuals.
The MHRA had been expected to approve the Johnson & Johnson vaccine imminently but will now extend its review to assess new data on the blood clots reported in the US.
Dr Siu Ping Lam, director of licensing at the MHRA, said: “No vaccine would be authorised for use in the UK unless the expected high standards of safety, quality and effectiveness have been met.
“Vaccine safety is of paramount importance and we will monitor and evaluate any safety reports received promptly and robustly before a decision is made, working and sharing safety data with international regulators as necessary.”
It’s not expected that the delayed approval will affect the UK’s rollout timeline, with three separate jabs currently being administered to the British population, including the newly available Moderna vaccine.
Another vaccine, produced by Novavax, is also being reviewed by the MHRA alongside the Johnson & Johnson candidate.
A Downing Street insider said the government would “continue to let the independent regulator do its work”.
However, the delayed rollout of the Johnson & Johnson jab on the continent is a further blow to vaccination efforts in the European Union, which has already been plagued by supply shortages, logistical problems and rising hesitancy surrounding the AstraZeneca vaccine.
The EU has ordered 200 million doses of the Johnson & Johnson vaccine for 2021. Germany, Italy, France and Spain were all set to receive hundreds of thousands of shots in the coming days, with plans to start administering them from next week.
The European Medicines Agency said it “is currently not clear whether there is a causal association” between vaccination with the jab and the rare blood clots.
The organisation’s safety committee “is investigating these cases and will decide whether regulatory action may be necessary”, the EMA added.
South Africa has also suspended its use of the Johnson & Johnson vaccine, having already administered more than 289,000 doses to the country’s health workers. Health minister Dr Zweli Mkhize said questions over the jab should “be cleared within a matter of days”.
The condition generating alarm is called cerebral venous sinus thrombosis (CVST), when blood clots in the veins that run from the brain, sometimes culminating in death.
In the cases of concern, which appear to be more prevalent in women under 60, this has been combined with thrombocytopenia, where a patient also presents abnormally low levels of platelets.
According to the MHRA, there have been 79 cases of CVST associated with thrombocytopenia in the UK, out of more than 20 million administered doses of the AstraZeneca vaccine.
In the US, the six cases linked to the Johnson & Johnson jab were all in women between the ages of 18 and 48. There was one death.
Eleanor Riley, a professor of immunology and infectious disease at the University of Edinburgh, said that although a causal link between the jabs and blood clots has not been confirmed, “the index of suspicion is rising that these rare cases may be triggered by the adenovirus component of the AstraZeneca and J&J vaccines”.
Professor Adam Finn, a member of the JCVI, said the number of cases remained very small but such developments do “raise the possibility that at least some adenovirus vectors either of themselves or in combination with the Sars-CoV-2 S [spike] protein gene can cause this idiosyncratic reaction in a very small proportion of individuals”.
He said an investigation of this phenomenon is “now an extremely urgent international priority” given the importance of the two vaccines to global efforts to bring the pandemic under control.
Dr Peter English, a former chair of the British Medical Association’s public health medicine committee, described the decision of the US health agencies to pause the use of the Johnson & Johnson jab as “highly precautionary”.
“The call for a pause may dent confidence in vaccination,” he added. “We must hope that, if it does, this will be temporary; and that the rapid action and openness will inspire confidence that vaccine safety is taken extremely seriously.”