The PM has not been able to make any phone calls to Ms Symonds who is only weeks away from giving birth to their first child.
Mr Johnson is still in intensive care with coronavirus but is sitting up and “engaging positively” with his medical team, Chancellor Rishi Sunak said yesterday.
No10 said the PM “continues to make steady progress” and is able to contact people he needs to.
A spokesman said: “He said: “The PM is not working, he’s in intensive care, he has the ability to contact those that he needs to, he’s following the advice of his doctors at all times.”
Friends of Ms Symonds said she was “distraught” when he was admitted to hospital and she was self-isolating with symptoms of COVID-19.
One cabinet minister said she was the only one in Downing street “who cares about his welfare”.
Ms Symonds wrote on Twitter that she was feeling “stronger and on the mend” after a week in bed with symptoms of coronavirus.
She added it was “obviously worrying” being pregnant while suffering symptoms.
Mr Johnson was taken to St Thomas’ Hospital on Sunday, and transferred to the ICU on Monday evening after his condition deteriorated.
He was given “standard” oxygen treatment but had not required ventilation and was not diagnosed with pneumonia.
The PM tried to keep up appearances for the country by having his parliamentary red boxes delivered to hospital, but handed the reigns of the Government over to Foreign Secretary Dominic Raab earlier this week.
Mr Sunak said yesterday: “The latest from the hospital is the Prime Minister remains in intensive care where his condition is improving.”
“I can also tell you that he has been sitting up in bed and engaging positively with the clinical team.”
He added: “The Prime Minister is not only my colleague and my boss but also my friend, and my thoughts are with him and his family. The news about the PM reminds us how indiscriminate this disease is.”
It could still be a long road to recovery for Mr Johnson once he does get better from the deadly virus, and is let out of hospital.
People around the country gathered on Tuesday night to clap for Mr Johnson and wish him a speedy recovery.
The spokesman for No10 said: “We are hugely grateful for the messages of support that the Prime Minister has received.”
Intensive care consultant at Imperial College London told BBC Radio 4: “When you are seriously ill it does take time to recover.”
“It’s not an all-or-nothing thing… but it can take many weeks to get back to normal full health or even months.”