HOW THE FLU JAB COULD BOOST YOUR IMMUNITY TO COVID

IF YOU aren’t fortunate enough to be naturally Covid-proof, is there anything else you can do to bolster the immune system and gain better protection against the virus?

There are, of course, the basics: staying a healthy weight, not smoking and getting a booster vaccine are all proven ways.

Vitamin D supplements have been touted, too, as the compound is known to be involved in the body’s immune response to respiratory viruses. But while this could theoretically work, at the start of December the National Institute for Health and Care Excellence concluded there was ‘little evidence for using Vitamin D supplements to prevent or treat Covid-19’.

One intriguing suggestion that holds more scientific weight is that getting a flu vaccine may also guard against coronavirus.

As reported by The Mail on Sunday last month, flu has all but disappeared for the second year running – and scientists now suggest that Covid vaccination, or infection, might ‘rev’ the immune system and guard against flu infection as a welcome secondary benefit.

But the same is thought to work the other way round: having a flu jab also boosts immunity against Covid.

When the body is infected with any virus, or is primed to recognise it by a vaccine, the immune system mounts a response, waking up its defence and fighter cells to guard against infection.

Flu-specific defence cells, or antibodies, which come from either having the infection or receiving a vaccine, are most effective at spotting the flu virus, quickly alerting other cells to an intruder.

But another key line of defence is fighter cells, called T cells, which are released after a jab or infection and are not as specific in their response.

‘Antibodies are like snipers and

can spot a particular illness and keep it out, while T cells are more like machine guns and offer more general protection against viruses,’ says Dr David Strain, senior clinical lecturer at the University of Exeter Medical School. ‘If someone has a good T cell response, their chances of infection with something else are a lot lower.’

Striking evidence from the US shows that people who had had a flu vaccine were 24 per cent less likely to catch Covid-19 – regardless of whether they’d had the Covid vaccine. And those who did contract Covid were less likely to need hospitalisation or ventilation.

The scientists, writing in the American Journal Of Infection Control, concluded that this pattern could be due to a strong T cell response following the flu jab.

And it’s not just antibodies and T cells: exposure to a virus or its vaccine can also ramp up another type of specialised cell – macrophages, which are particularly effective for fighting respiratory viruses.

‘Macrophages destroy bacteria, so clear debris and dead viral cells in the lungs,’ explains Professor James Stewart, Chairman of

Molecular Virology at the University of Liverpool.

‘This is helpful with both flu and Covid-19. So exposure to both viruses hypes up the immune system, meaning that people will get some protection against both.’