Flu: have you had your jab yet?
Covid may have dominated the agenda for the last 18 months, but a more familiar respiratory disease is threatening to complicate the country’s health response this winter: flu.
Modelling from the Academy of Medical Sciences puts the likely range of flu deaths this year at a grim 15,000 to 60,000. It kills around 11,000 people a year on average in England. In the last bad flu year of 2017/18 it was twice this number, with around 300 deaths a day at the peak.
The threat of a devastating flu season has prompted the NHS to launch its biggest ever flu vaccination drive. More than 40 million people are being offered a jab, five million more than last year. Those who are over 50, pregnant or who live in care homes, as well as frontline health workers, are among the groups being encouraged to come forward. If you live in England, you can book an appointment through your GP or local pharmacy.
While flu vaccines are perfectly safe, their efficacy varies substantially year to year. A global network of virologists must predict which of the millions of rapidly changing flu viruses in circulation are likely to become dominant in the upcoming flu season, so that vaccines can be tailored accordingly.
Whether or not they get it right has a dramatic effect on efficacy, which can be very low. Flu jabs prevented between 15 per cent and 52 per cent of infections in the UK each year between 2015 and 2020.
But the on-off lockdowns and social distancing measures of last winter meant flu was circulating at lower levels than normal. According to the WHO, there has been a 99 per cent reduction in the number of positive flu samples in the northern hemisphere compared to previous years. The lack of data has made it harder to sample and predict new strains. A mismatch between the flu jab and virus in 2015 contributed towards a big spike in cases.
Weaker immune systems are also a concern. As Professor Jonathan Van-Tam, deputy chief medical officer, points out: “Not many people got flu last year because of Covid-19 restrictions, so there isn’t as much natural immunity in our communities as usual.
“We will see flu circulating this winter; it might be higher than usual and that makes it a significant public health concern.”
How it will interact with Covid is another big unknown. Jenny Harries, head of the Health Security Agency, says: “This is probably the first season where we will have significant amounts of Covid circulating as well as flu” and people are “at more significant risk of death and of serious illness if they are co-infected” with both viruses. PHE research suggests that those who come down with flu and Covid are twice as likely to die as those who catch Covid alone.
The government is banking on vaccines coming to the rescue once again. Covid booster jabs are being rolled out for at-risk groups to combat waning immunity. And the NHS is aiming to beat last year’s record flu vaccine uptake of 80.9 per cent of over-65s in England.
It could be that with high uptake of an effective vaccine, a mild winter and a following wind, the feared “twindemic” of Covid and flu never materialises, as in 2020.
The reality is that with so many variables at play, predicting the impact of flu this winter is still difficult. Best to get your vaccination before the season starts in two to three weeks time.