Do I really need a fourth Covid jab?

As the weather turns and autumn beckons, a swift reminder that the battle with Covid is far from over has arrived in the form of a text or email inviting those eligible to book in for their Covid-19 autumn 2022 booster. Around 26 million people in England are eligible, including adults aged 50 and over. But with Covid now a relatively mild illness – for most of us who are vaccinated – do we really need it?  

Around half the population – 33.5 million – has now had three doses of the Covid vaccine and 42.6 million have had two, providing (you’d think) solid grounds for protection. With this in mind, we ask some of the country’s leading experts if we should still be taking up this offer of a booster and why…

How much immunity do we have currently?

“Immunity in the population overall has certainly not all gone and we are definitely not starting from scratch,” says Professor Paul Hunter, an expert in infectious diseases and Professor in Medicine at the University of East Anglia. “Immunity against infection from either vaccine or prior infection is relatively short lived (months rather than years) and does not transfer well to new variants. But protection against severe disease is more durable.  According to a recent study on long-term immunity in healthcare workers, people with hybrid immunity having had both the vaccine and infection have better protection going forward than those who just had the vaccine or just had an infection.”

Professor Peter Openshaw, mucosal immunologist and respiratory physician at Imperial College London, states that, while immunity is remaining after previous vaccines and boosters, effectiveness, “drifts down over time” hence our need to top up with another booster regardless of which variant we’ve had. The latest government report on vaccine effectiveness dated September 1 2022 confirms this and revealed that, after two doses of the AstraZeneca vaccine, vaccine effectiveness against the Omicron variant starts at 45 to 50 per cent then drops to almost no effect from 25 weeks after the second dose. With two doses of Pfizer or Moderna, effectiveness dropped from around 65 to 70 per cent down to around 15 per cent by 25 weeks after the second dose. “Boosters are very important in getting immunity back up as they stimulate a greater magnitude immune response and higher levels of antibodies,” adds Professor Openshaw. “And with resurgence of infections likely in autumn/winter, now is the time to get one.”

Why do we need a booster now?

More than 24,000 people in England tested positive for the virus in the last week of August, although with fewer people testing and many non-symptomatic, there are likely to be thousands more who have it.

And cases are expected to rise in the coming months. “We see this with most respiratory viruses – they circulate much more heavily in the winter months,” says Dr Elly Gaunt, virologist at University of Edinburgh. “This is because people gather inside, spreading the virus in tiny droplets when they speak but also through aerosol transmission where the virus particles are so small, they float and travel around on air currents and can move from one side of a room to another.”

According to Professor Hunter, winter will put many of the more vulnerable people at risk. “While most of the adult population have had a vaccine and had an infection, more of the more vulnerable people (those in older age groups and probably those with underlying medical conditions) have yet to have their first infection so protection against severe disease from earlier vaccination will be waning in this group,” he explains. “If they do catch Covid, they are at risk of severe disease.”

What’s in the new booster?

The jabs will be one of the mRNA vaccines and either the new version of the Moderna or Pfizer jabs, which protect against two strains of Covid, the Delta variant and more recent Omicron. Government literature on the boosters refers to them as the “combination vaccines” which include “a half-dose of the previous vaccine combined with a half-dose of a vaccine against the Omicron variant”, producing slightly higher levels of antibody against some strains of Omicron. “Because it’s been updated to include the Omicron variant, the antibodies will be a better match for the viruses circulating right now,” says Dr Gaunt.

What are the side effects?

Common side effects are the same as the previous vaccines – having a painful, heavy feeling and tenderness in the arm where you had your injection, feeling tired, headache and general aches or mild flu-like symptoms. “As with all vaccines, local and short-term side effects such as pain at the injection site and fever are common,” says Professor Hunter. “The main concern of more severe effects is myocarditis, inflammation of the heart, but these tend to be seen primarily in younger people who will not be offered the booster.”

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