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UKHSA warns of lower levels of natural immunity to flu this year and increased COVID-19 circulation

The UK Health Security Agency in the South West is urging everyone eligible for a free flu vaccine and a COVID-19 booster to take up the offer as soon as possible ahead of what could be a difficult winter with respiratory viruses circulating widely.

International surveillance shows that H3N2 – a subtype of influenza type A – is currently the most-commonly detected flu virus worldwide. H3N2 has recently caused waves of infection in southern hemisphere countries such as Australia, which has also experienced flu circulating earlier than usual in their winter season.

This H3N2 strain circulated in the UK last winter but was held largely in check by COVID-19 restrictions when people mixed a lot less and worked from home. This helped to protect people from catching flu but has also led to lower levels of natural immunity to this strain building up within the population.

There was record uptake of the flu jab in people aged 65 and over in 2021/22 (82%), though there was lower uptake among people in clinical risk groups and pregnant women and these groups are particularly encouraged to come forward this year.

All primary school children and some secondary school children are eligible for the flu nasal spray this year, which is usually given at school. GP surgeries are also inviting children aged two and three years old (age on 31 August) for this nasal spray vaccination at their practices. Most young children will not have encountered flu yet. This means they will not have built up any natural immunity to this virus, so it is particularly important for them to take up the flu vaccine this year.

In addition to the predicted flu wave, we have early indications that COVID-19 rates are beginning to rise ahead of winter, increasing the threat to people’s health.

Study results from early in the pandemic show individuals who catch both flu and COVID at the same time, known as co-infection, are around twice as likely to suffer death compared to those who only have COVID-19.

For all those who are eligible, taking up both the COVID-19 booster and the flu jab is an essential form of protection against the most severe respiratory viruses in circulation this winter.

As well as taking up the vaccines, everyone is encouraged to help stop the spread of respiratory viruses this winter by practising good hand hygiene, wearing masks in crowded or enclosed public spaces and covering your nose and mouth when you cough and sneeze.

Dr Susan Hopkins, Chief Medical Advisor 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.”

Professor Dominic Mellon, UKHSA South West Regional Deputy Director, added:

“Both flu and COVID-19 can cause serious illness and hospitalisation and this winter they will be circulating together. This along with lower levels of natural immunity will mean that it’s particularly vital to get vaccinated, especially if you’re in a higher risk group.

“Undoubtedly the best protection we have is to get vaccinated. The jabs are there to protect you and the rest of your family from a potentially very serious illness this winter and so I urge all those eligible in the South West to come forward and have their jabs when offered.

“We must also remember that living with Covid means doing what we can to reduce the spread of the virus. Try to meet in well-ventilated spaces, wash your hands regularly and stay away from others where possible if you have symptoms of a respiratory illness. You can find more advice and guidance on the Government website at”

Deputy Chief Medical Officer Dr Thomas Waite said:

“Vaccines have saved many lives over the years for both flu and more recently Covid. But we must not be complacent – infections will rise once again this winter, so it’s really important people get both their Covid and flu vaccines if eligible.

“Vaccines are the best way to protect yourself from serious illness and will help reduce pressure on the healthcare system.”

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.

“If you have been offered a flu vaccination or Covid booster you should book in as soon as possible and with more vaccination centres than ever before this year, they are quick, convenient and will provide vital protection this winter.”