France, Germany, Spain and Italy joined several other European countries in temporarily halting the use of the Oxford-AstraZeneca Covid-19 vaccine Monday over concerns that the shots may be linked to an increased risk of blood clots. But experts say no causal link has been identified so far, and they cautioned that the suspensions might wind up doing more harm than good.
A growing number of European countries opted to pause the rollout of the vaccine after there were reports that a small number of patients developed blood clots after receiving at least one dose.
The World Health Organization said Monday that "there is no evidence that the incidents are caused by the vaccine" and advised that vaccination campaigns should continue while the clotting concerns are investigated. Several experts agreed that without a higher burden of proof, the suspensions could ultimately drive future outbreaks — particularly because they are coming at a precarious time for Europe in the pandemic.
"There's still a lot of Covid around Europe, so given that this is a public health emergency, you would need to see a pretty strong signal in the data to suspend a vaccine program," said Michael Head, a senior research fellow in global health at the University of Southampton in the United Kingdom. "If we have this scare and there's nothing there, will there be more cases and deaths from Covid-19 because of delays in the vaccine rollout? Will it increase vaccine hesitancy?"
Head said that while any potential side effect should be investigated thoroughly, decisions to halt vaccination campaigns need to strike a delicate balance between risks and benefits. At the moment, he said, there are no data to suggest that AstraZeneca shots are tied to blood clots.
"I can't see a strong enough signal to warrant withdrawing the vaccine from national rollouts," Head said. "Given that there's still a lot of Covid around Europe and the emergency of the situation, I'm not sure why vaccine programs are being suspended."

We should have confidence in the vaccine .Stopping vaccination may cause greater harm.