
The Conservatives have criticised the National Flu Service, claiming the system is "too little, too late".
The flu advice website, covering England, crashed on Thursday after it was overwhelmed with 9.3m hits an hour.
Tory health spokesman Mark Simmonds said the web and telephone service should have been set up earlier when a global pandemic was declared. The NHS is facing "exceptional"
levels of demand over swine flu
The Department of Health said it had worked quickly to quadruple the site's capacity and it was now working well.
The swine flu service went live as it emerged that the number of new infections in England had doubled in the past week, with an estimated 100,000 new cases reported.
Meanwhile, a pregnant woman critically ill with the H1N1 virus has been transferred to Sweden to receive specialist treatment.
The 26-year-old was admitted to Crosshouse Hospital in Kilmarnock, Ayrshire, but was moved after suffering an extreme reaction.
She is undergoing a procedure called extra corporeal membrane oxygenation (ECMO) in which her blood will be circulated out of her body and oxygen added artificially.
Dr Palle Palmer, from Karolinska University Hospital, said the treatment would buy the patient some time and allow her body to recover.
Patients have been transferred between Sweden and the UK for this treatment commonly for the past decade he added.
'Under review'
The National Flu Service offers sufferers access to drugs on the phone and via the internet without the need to see a GP.
The government said demand was "unprecedented", with 2,600 hits a second. The site crashed shortly after its launch at 1500 BST, but was was back up and running two and half hours later.
Chief Medical Officer Sir Liam Donaldson said they had increased capacity but expected demand to drop.
Sir Liam Donaldson: "There will be an element of the worried well"
"Our initial analysis suggests many people visited the site out of curiosity, they started to check the checklist and then abandoned it.
"We have quadrupled capacity but we're not expecting people to remain curious for very long."
But the Tories said there was "still far too much confusion about access to diagnosis and treatment for swine flu".
On Thursday, Shadow health secretary Andrew Lansley said the advice service was "unable to cope with demand" and was "too little, too late".
And on Friday, Mr Simmonds told BBC Radio 4's Today programme: "We should have had the flu line and the website up earlier. We should have gone live when the WHO [World Health Organisation] said we had pandemic levels.
"Indeed, the fact that the website crashed yesterday within two to five minutes of it being up and running, I think, is a function of the fact that it wasn't up earlier.
"Therefore, people couldn't access the information, they couldn't discover themselves whether they had the appropriate symptoms that would give them the opportunity to get Tamiflu.
"I think it is a direct result of that."
The latest death toll from swine flu stands at 26.
The DoH said two-thirds of the deaths were among people with severe health conditions, such as cancer.
Some 840 patients are in hospital - 63 of which are in critical care - compared to 652 last week.
Checklist
To contact the National Flu Service, people in England can call 0800 1 513 100 or log on to www.direct.gov.uk/pandemicflu
The flu service is not covering the rest of the UK as Wales, Northern Ireland and Scotland have all experienced much less demand.
People with underlying health problems, pregnant women and parents concerned for children aged under one are still being advised to contact a GP.
A checklist is being used by call centre staff and the website to decide whether people have swine flu.
If the virus is suspected, people will be given a voucher number to give to a flu friend to take to a collection point to pick up anti-flu drugs.
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