As the Government announces plans to introduce booster jabs for Covid-19 — making us the first country in the world to do so — Rachel Ellis asks some of the country's leading experts to explain why boosters might be necessary.
What is a booster jab and why would I need one?A booster jab increases the number of immune cells capable of producing antibodies to fight off the virus, explains Will Irving, a Professor of Virology at the University of Nottingham.
'The first vaccine allows your immune system to 'see' the pathogen [the virus in this case] for the first time, which means the body can lay down memory cells containing information about it.' The second Covid jab is not a booster, it's part of the initial course of injections.
'Anything subsequent to that is a booster,' Professor Irving explains.
'For some vaccines, the primary course may involve three jabs (hepatitis B, for example), or just one jab (as with MMR, given at 12-18 months). There are no hard and fast rules.'
A booster jab increases the number of immune cells capable of producing antibodies to fight off the virus, explains Will Irving, a Professor of Virology at the University of Nottingham. A woman is seen being vaccinated in London
As to why you need a booster, he explains that the first vaccine often generates a slow, small response in the immune system because it is seeing something brand new, and this response will fade fairly quickly. The second dose generates a quicker, bigger and longer-lasting response from the immune system.
Crucially, though, Professor Irving says: 'This, too, will fade over time, as the memory cells reach the end of their natural life, leaving the individual with less protection.
'A booster jab stimulates the immune system again so that it makes more memory cells that produce antibodies.
'Exactly how long it takes for antibody levels to drop after the first round of vaccination depends on many things, such as the pathogen and type of vaccine,' he adds.
When it comes to Covid, scientists will only know how long the protection lasts by studying real people over time.
But I've heard that the vaccine can provide lifelong immunityNo vaccination provides 100 per cent protection from a disease, but research so far shows that Covid vaccines are very effective, preventing symptoms in more than 90 per cent of people who are fully vaccinated.
Furthermore, Public Health England data shows that both the Pfizer and AstraZeneca (AZ) vaccines are more than 90 per cent effective after two doses against hospitalisation with the Delta variant.
A study published last month in the New England Journal of Medicine suggested that the Moderna vaccine provides protection for at least six months.
Meanwhile, a study published in the journal Nature in May found that people who'd had mild cases of Covid-19 were still producing antibodies against the virus eight months later — and based on previous experience, this could continue for decades.
A study published last month in the New England Journal of Medicine suggested that the Moderna vaccine provides protection for at least six months. People are seen in a queue outside Tottenham Hotspur's football stadium in London
But the effectiveness of any vaccine depends on many factors, including age. Our immune response declines as we get older, which is why flu and pneumonia vaccines, which are largely aimed at older people, contain adjuvants — compounds such as aluminium salts that boost the immune response.
The vaccine's effectiveness can also be affected by conditions that weaken the immune system, including obesity.
Does it make any
