Wales' Health Minister has said they are "particularly worried" about pregnant women who have not been vaccinated.
Speaking at a briefing on the latest situation in Wales on Tuesday (September 14), Eluned Morgan urged mums-to-be to speak to their midwife about having the vaccine.
She told a press conference: "Vaccination has made a real difference to the course of this pandemic – it has prevented many thousands of people falling seriously ill and it has prevented many, many deaths in this delta wave.
"We have very high rates of vaccination in Wales – thanks to the hard work of everyone involved in our fantastic programme – but there are many people who could be vaccinated who have not yet had a vaccine.
"We are particularly worried about pregnant women who haven’t been vaccinated and would urge them to speak to their midwife about having the vaccine. It’s never too late to be vaccinated in Wales.
"Please, if you haven’t already, come and get your vaccine and when your invite arrives, come and get your booster."
Read more: All the questions pregnant women have about the coronavirus vaccine answered
Last month new research showed that catching Covid during pregnancy could make the unborn child more prone to diseases. Read more about the findings here.
Mild infections in the mother can permanently damage the immunity of offspring, scientists said.
Experts also say there is no increase in stillbirths or premature births, no abnormalities with development, and no evidence of babies being smaller or bigger.
In the UK, pregnant women are offered the Pfizer/BioNTech or Moderna vaccines where available, as officials say there is more safety data on these jabs in pregnancy.
Gill Walton, chief executive of the Royal College of Midwives, encouraged mothers-to-be with questions to ask medical professionals.
She said: "Hundreds of thousands of pregnant women worldwide have been vaccinated, safely and effectively protecting themselves against Covid and dramatically reducing their risk of serious illness or harm to their baby.
"If you have questions, please talk to your midwife, obstetrician or GP. Get the answers you need and get the jab."
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