Hillary Clinton collapse: Democratic candidate 'diagnosed with pneumonia' after stumbling at 9/11 event

The candidate's doctor issued a statement after seeing Ms Clinton at her home

The issue of Hillary Clinton’s health has moved front and centre to the presidential election campaign after her doctor said she was being treated for pneumonia - hours after she stumbled and felt unwell at a 9/11 memorial service.

Dr Lisa Bardack said Ms Clinton was “recovering nicely” after attending the event in lower Manhattan on Sunday morning. Ms Clinton was seen on video struggling to stay on her feet, and had to be helped by Secret Service staff as she got into a vehicle to leave the event early.

Ms Clinton, 68, was due to fly to San Francisco and Los Angeles on Monday, but a campaign official said she had cancelled the two-day California trip that was to include a key speech on the economy and fundraising events.

Ms Clinton appeared to stumble as she got into her vehicle (YouTube)

The huge injection of drama into the campaign came as Ms Clinton’s lead over rival Donald Trump had been slipping, both nationally and in some of the crucial swing states that will likely decide the race. Her campaign has also been fighting allegations from Mr Trump and his supporters that she is seriously unwell and trying to conceal something from the public.

On Sunday evening, US media were quick to ask why, given that Ms Clinton was apparently diagnosed with pneumonia on Friday, her campaign failed to disclose this until it was effectively forced to do so.

Mr Trump, who also attended the same event as Ms Clinton, was conspicuously silent about the development, his only comment on the 15th anniversary of the attacks on New York and Washington, being a statement calling on people to pray for those lost in the Al-Qaeda assault that left almost 3,000 people dead.

Asked by a reporter about the incident, Mr Trump said: “I don't know anything.”

News that Ms Clinton had stumbled and left early from the event was first reported by Fox News, one of the channels which has been providing a platform for opponents of the candidate to make allegations about her health.

It said she had left early after standing for 90 minutes in the humidity at Ground Zero. She walked away from the ceremony but was seen to trip and stumble as she climbed into a waiting van.

For an hour-and-a-half, the media pool traveling with her had no idea where she was, and the candidate’s campaign declined to provide details.

It then transpired that Ms Clinton had been driven to her daughter’s apartment in the Flatiron neighbourhood of the city. Around noon, she emerged, walking by herself, and waving to the media and waiting crowds.

She briefly posed for a photograph with a young girl. To a shouted question from a reporter as to whether she felt better, she said: “Yes, thank you.”

“I’m feeling great,” Ms Clinton said. “It’s a beautiful day in New York.”

Her campaign spokesman said that Ms Clinton had left the event because she had overheated.

“During the ceremony, she felt overheated so departed to go to her daughter's apartment, and is feeling much better,” spokesman Nick Merrill said in a statement.

Ms Clinton was then taken to her home in upstate New York where the media gathered in a nearby hotel. It was then that Ms Clinton’s doctor issued the details about her diagnosis.

Ms Bardack said that Ms Clinton had had an allergy-related cough, and that during a follow-up examination Friday, the candidate was diagnosed with pneumonia, put on antibiotics, advised to rest and modify her schedule.

“I have just examined her and she is now rehydrated and recovering nicely,” she said, according to the Associated Press.

It remains unclear how serious Ms Clinton’s condition is, and how much it will impact her campaign. What is clear is that the episode looked serious, and was being used by her critics as evidence of her unsuitability for the White House.

With many polls showing Ms Clinton’s lead over Mr Trump narrowing, she created controversy last Friday by claiming that half of Mr Trump’s supporters were a “basket of deplorables” - a comment that drew sharp criticism from Republicans.

Ms Clinton later said she regretted applying that description to “half" of Mr Trump’s backers, but stuck by her assertion that the Republican nominee has given a platform to “hateful views and voices”.

Mr Trump and Ms Clinton are among the oldest candidates to contest for the White House in US political history. Mr Trump has sought to question Ms Clinton’s physical and mental ability to do the job. Ms Clinton and her supporters have repeatedly questioned the New York tycoon’s temperament.

Ms Clinton suffered concussion in December 2012 after fainting. Her doctor attributed that episode to a stomach virus and dehydration.

Ms Clinton’s doctor reported she is fully recovered from the concussion, which led to temporary double vision and discovery of a blood clot in a vein in the space between her brain and skull.

Ms Clinton also has experienced deep vein thrombosis, a clot usually in the leg, and takes the blood thinner Coumadin to prevent new clots. In July 2015, Ms Clinton issued a detailed two-page letter from her physician that included the concussion.

Mr Trump’s personal physician has said the Republican presidential nominee is in excellent health both physically and mentally. But the former reality television star has refused to release his own health records.

Dr Harold Bornstein’s report last December remains the only medical information released so far by the Mr Trump campaign.

Mr Bornstein told NBC News he needed just five minutes to write a glowing public assessment of Mr Trump's health as a limousine waited to carry the letter back to the tycoon.