The number of scarlet fever cases is currently triple what doctors usually see, a senior health official has claimed.
At least 19 children have now died from Strep A-related illnesses, the latest figures show.
The latest deaths include seven-year-old Hanna Roap, from Penarth, South Wales, and a child from Powys who has not been named.
The deaths also include five-year-old Stella-Lily McCorkindale from Belfast and Muhammad Ibrahim Ali, four, from High Wycombe, Bucks.
One senior health expert however has said the 7,500 cases recorded so far are likely not the full extent of the outbreak.
Professor Susan Hopkins, chief medical adviser at the UK Health Security Agency (UKHSA), said the bacteria usually only caused a mild illness and that an “open mind” is being kept as to why there is a spike in infections.
Speaking on BBC Radio 4’s Today programme, she said: “The latest with scarlet fever and Strep A infections are that we’ve seen about just over 7,500 notifications of scarlet fever, and that’s probably an underestimate.
“We have a lot of reports coming in in the last few days so we expect it to be even higher.
“That’s about three times higher than the same time in a normal season. The last bad season we had in 2017 and 18.
“And in invasive Group A Strep cases, we are more than halfway through what we’d normally see in an average season.
“We’ve seen 111 cases in children aged one to four and 74 cases in children aged five to nine.”
Invasive group A strep (iGAS) is the most severe and unusual form of infection.
She said those numbers at the severe end are small, adding: “The vast majority of children have a self-limiting or mild illness and are being managed very well.”
Meanwhile, Prof Hopkins said analysis shows that areas of the country where children had the flu nasal spray vaccine has had lower Group A strep infections compared with areas of the country that had not yet started to roll out the vaccine.
She said flu infections and other viral infections have a greater propensity to have a secondary bacterial infection on top, adding that children who normally catch influenza are at greater risk of other subsequent infections, including Group A streptococcus.
“And therefore what we’ve done here is an analysis of looking at the rollout of the nasal spray flu vaccine, which is the vaccine that’s given to children from the age of two, and what we can see here is in areas of the country where we gave the vaccine there were lower Group A strep infections compared to areas of the country that had not yet started to roll out the vaccine,” she said.
All children aged two and three are eligible for a flu nasal spray vaccine, which is being offered by GPs.
But only 37.4% of two-year-olds have received the vaccine so far, along with 39.5% of three-year-olds – well below the take-up reached at this point in previous winters, the latest data shows.
Prof Hopkins said children younger than school age can get the vaccine from their GP, while children in school can get the vaccine through the school vaccination service.
“If you’ve yet to sign that consent form for the school vaccine, then please do, and if your child is preschool, please make an appointment for your GP,” she said.
Prog Hopkins was asked if it is yet known why there has been a spike in infections of scarlet fever and Strep A and whether it is due to children’s immunity levels being weakened after socialising less during the pandemic.
“We would not say we’re convinced of anything yet. I think we’re seeing this season much, much earlier,” she said.
“We’ve got a lot of children who have not had this infection over the last three years, so there’s more susceptible children who have not started to develop their immunity to this infection, which we get repeated times over the course of our lives.
“Of course, we’re always looking for other reasons. Has the bacteria changed? Is there any other changes in that might have occurred that are causing this? So while we think at the moment, the most likely explanations from everything we’ve looked at, is the fact that this relates to lack of exposure for a period of time, we will keep an open mind and look elsewhere.”
It is understood that health officials do not believe the number of scarlet fever infections has yet peaked, suggesting more deaths are likely.
Strep A infections such as scarlet fever and impetigo are treated with antibiotics, with penicillin among the most commonly used.
The Government has introduced serious shortage protocols (SSPs) for three penicillin medicines.
The move means pharmacists can legally supply alternative forms of the medicine if they do not have the specific formulation stated on the prescription, such as an oral solution.
Scarlet fever symptoms are often flu-like, including a high temperature, a sore throat and swollen neck glands.
A rash appears 12 to 48 hours later, starting on the chest and stomach and then spreading.
A white coating also appears on the tongue which peels, leaving the tongue red, swollen and covered in little bumps (often called “strawberry tongue”).
