What is a ‘twindemic’? UK faces ‘difficult winter’ of Covid and flu - health chiefs’ warning explained

The UK could face a “twindemic” of flu and Covid this winter, health chiefs have warned.

Officials at the UK Health Security Agency (UKHSA) say there will be lower levels of natural immunity to flu this year as they launch a renewed vaccination drive.

Millions of people are being urged to have flu and Covid jabs as experts fear there could be a bad flu spike this year after several winters when people socialised less due to the pandemic.

What have health chiefs said?

The UKHSA has warned of a “difficult winter” ahead as respiratory viruses, including flu and Covid, circulate widely.

International surveillance shows the UK can expect the spread of H3N2 (a subtype of influenza type A), which is currently the most commonly detected flu virus worldwide.

H3N2 has recently caused waves of infection in countries including Australia, which has just had its winter, but the vaccine used by the UK is designed to fight this strain.

In 2017/2018, the H3N2 flu strain led to a severe UK flu season, with around 20,000 deaths and 40,000 hospital admissions. It did circulate in the UK last winter but as there was less social mixing due to Covid it means there is little immunity to it.

NHS Providers said trust leaders are now “bracing themselves” for a possible “twindemic”.

NHS director for vaccinations and screening Steve Russell said: “This winter could be the first time we see the effects of the so-called ‘twindemic’ with both Covid and flu in full circulation, so it is vital that those most susceptible to serious illness from these viruses come forward for vaccines in order to protect themselves and those around them.”

Who is eligible for flu and Covid jabs?

Under plans announced on Wednesday, around 33 million people in England will be eligible for a free flu vaccine this year, including all primary-age and some secondary-age children, who will be offered the nasal spray.

Those eligible for the flu jab include:

• people aged 50 and over
• those aged six months to 49 with a specified health condition
• secondary school-aged children focusing on Years 7, 8 and 9 with any remaining vaccine offered to Years 10 and 11
• primary school-aged children
• pregnant women
• people in care homes
• frontline health and social care staff
• carers 
• household contacts of people with weakened immune systems

These people can get a flu jab from their GP surgery or pharmacies offering an NHS vaccine service. GPs are also inviting children aged two and three years old (as of 31 August) for the nasal spray vaccine.

Around 26 million people in England are also eligible for the autumn Covid booster vaccine. People who qualify for the autumn/winter booster include:

• adults aged 50 and over
• those aged five to 49 with health conditions that put them at greater risk
• pregnant women
• care home workers
• frontline health and social care workers
• carers 
• household contacts of people with weakened immune systems

All those eligible for a booster can now book online, except for people aged 50 to 64 (who are not in an at-risk group) who will be able to get their vaccine later this autumn.

People with asthma are not routinely offered a Covid booster vaccine due to the lack of evidence they are at higher risk from the virus. However, a subset of people with asthma (such as those with very poorly controlled asthma) are offered a dose.

People who qualify for both jabs could be offered the flu and Covid jab at the same time if supply allows, with each vaccine to be given in a different arm.

‘Early indications’ Covid rates are rising

As well as the predicted flu wave, the UKHSA has warned there are “early indications” that Covid rates are beginning to rise ahead of winter.

Dr Susan Hopkins, chief medical adviser at UKHSA, said: “Flu and Covid-19 are unpredictable but there are strong indications we could be facing the threat of widely circulating flu, lower levels of natural immunity due to less exposure over the last three winters and an increase in Covid-19 circulating with lots of variants that can evade the immune response.

“This combination poses a serious risk to our health, particularly those in high-risk groups.

“The H3N2 flu strain can cause particularly severe illness. If you are elderly or vulnerable because of other conditions you are at greater risk, so getting the flu jab is a sensible, potentially life-saving thing to do.

“We are extremely fortunate to have vaccines against these two diseases. Most eligible groups have been selected because they are at higher risk of severe illness.

“Younger children are unlikely to have built up any natural immunity to flu and therefore it is particularly important they take the nasal spray vaccine this year.

“So, if you are offered a jab, please come forward to protect yourself and help reduce the burden on our health services.”