The Stroke Foundation is urging people to get vaccinated against Covid-19 to help reduce the risk of a debilitating stroke.
Its chief executive Jo Lambert told Morning Report new studies show more severe infections of Covid-19 create a higher chance of stroke.
Stroke is the largest cause of serious adult disability in this country, and the second-highest cause of death in New Zealand, after cancer.
"There's an increasing body of international clinical research showing that the incidents that stroke increases if you are infected with Covid. This research is coming from the Netherlands, France, America, Sweden and it's been published in recognised medical journals such as The Lancet," Lambert said.
"The statistics are quite alarming ... for instance, a population-based study done in America of 20,000 people showed of those people, 281 people went on to have a stroke."
Lambert said there were three main reasons Covid-19 was increasing the risk of a stroke.
"It impacts the cell lining of our blood vessels, and that can cause clots to spin-off and cause a stroke, enter the brain and cause a stroke.
"Also the fact that our own immune system is activated when we get Covid-19, and that in itself can cause some blood clotting.
"And the third thing is that we believe that Covid is triggering its own blood clotting in order to help it survive in the body."
She said there was nothing currently to suggest an increase of strokes in New Zealand.
"So any myths about there being a risk in having the vaccine and that might then trigger a stroke is just not the case.
"The fact is, is that the more severe case you have of Covid, the more likely you are to have a stroke and that increases markedly based on this research."
The vaccine reduced the risk of contracting Covid-19 and thereby risk of stroke, Lambert said.