A cervical cancer vaccine given to a 14-year-old girl shortly before she died has a "good safety profile", a charity said today.
Health authorities launched an urgent investigation after Natalie Morton died in hospital yesterday after receiving the HPV1 Cervarix jab at the Blue Coat Church of England School in Coventry.
Jo's Trust, a charity set up by a businessman in memory of his wife who died from cervical cancer, urged parents not to panic and said the vaccination programme should continue.
But the Family Education Trust (FET), which researches the causes and consequences of family breakdown, said the longer-term effectiveness of the vaccine was uncertain and could lead to a "false sense of security" among young people.
Post-mortem tests were being carried out today to see if there was a link between the vaccine and Natalie's death.
Robert Music, director of Jo's Trust, said: "Our sympathies go to the family. Obviously, it's an absolute tragedy that a 14-year-old girl has died.
"Until we understand what has happened and whether there's a link or not (with the vaccine), it's very hard to comment on that side of things.
"In regard to the vaccine itself, we would urge parents not to panic as a result of this. It's a vaccine that can, potentially, reduce by 70% the chances of being diagnosed with cervical cancers.
"Well over one million doses have been given and it has a good safety profile. I know that it's approved in about 100 countries around the world.
"I think it's important the programme continues. It's a programme that saves hundreds of lives a year."
But Norman Wells, of the FET, said the "controversy" over the vaccine would remain - "irrespective" of whether it was linked to the schoolgirl's death.
"Our hearts go out to Natalie's family and friends at this time and it is clearly premature to speculate on the cause of her death as the investigation gets under way," he said.
"Irrespective of whether a link is established between the HPV vaccine and this tragic death, the controversy surrounding the mass immunisation programme will remain.
"Medical researchers have long warned that there is a possibility that the HPV types targeted by the vaccine could be replaced with other high-risk types for which the vaccine offers no protection.
"Given the uncertainty as to the effectiveness of the vaccine over the longer term, it is simply not possible to accurately estimate either its impact or its cost-effectiveness.
"Equally seriously, the vaccination programme may give young people a false sense of security and lead them to think that, because they have been vaccinated, they are protected against the worst effects of sexual promiscuity and can, therefore, engage in casual sex without consequence."
He said the "best protection" would be provided by "abstaining from sexual intimacy or keeping sex within a lifelong mutually faithful union between a husband and wife".
Professor Malcolm McCrae, virologist at the University of Warwick, said: "As with any medical intervention, vaccines are no different in the sense that one can, on rare occasions, see tragic consequences.
"But overall this is an extremely well-tested vaccine which has been produced in response to a critical health issue - cervical cancer, a disease responsible for almost 1,000 deaths annually in the UK."