What’s going on with booster jabs?

As it stands, three things remain certain. Firstly, that people require two doses of the Covid vaccine for the best level of protection. Secondly, that protection from the vaccine remains strong for a minimum of three months up to six months (for the Pfizer jab in particular), and thirdly, that it’s looking increasingly likely people in the more vulnerable groups will need a booster later in the year.

Trials are underway to figure out what kind of boosting regime works best and reports suggest it’ll be the over-50s who will be prioritised for a third jab – possibly as early as autumn. It’s unclear whether younger groups would also need a booster, although given that many haven’t received their first dose yet, any booster for those of working age will likely be issued in 2022.

Vaccine manufacturers don’t know for certain how long protection from their vaccines last – studies into this are ongoing. Pfizer, for example, is monitoring clinical trial participants for up to two years to study long-term immunity. Initial studies show antibodies do decrease in people who’ve had the Pfizer vaccine over a six-month period. That said, the company says the vaccine continues to be effective against the virus through these six months.

“Our current thinking is that until we see a reduction in SARS-CoV-2 circulation and Covid-19 disease, we think it is likely that a third dose, a boost of our vaccine, will likely be needed to help provide protection against Covid-19, subject to approval by regulatory authorities,” a Pfizer spokesperson says.

What do scientists predict about the need for regular Covid vaccines?

Professor Daniel Altmann, an immunologist at Imperial College London, isn’t so sure boosters will be needed every year. “Many, including Matt Hancock, seem to be talking about ‘annual boosters’ from autumn, both to keep immunity high and in case of new vaccine versions against variants,” he tells HuffPost UK. 

“I’m less convinced this is a certainty. I wonder if there’s some confused thinking, that this is going to pan out like seasonal flu vaccination.”

The existing Covid vaccines are “really potent”, he says, and from the data he’s seen, he’d expect any fully vaccinated person (meaning someone who’s had two doses) to be protected for two years “at the very least”.

“Then, in terms of currently known variants, the current evidence again is that anyone who receives two vaccine doses has sufficient cover,” he explains.

With the latest variant – B1617.2, which originated in India – studies suggest there’s some variation in how well vaccines work against it. The overall takeaway is after two doses, most people should have pretty good protection.

In a preprint study from Public Health England (PHE), the Pfizer vaccine was found to be 88% effective against the new variant two weeks after the second dose, while the AstraZeneca vaccine was found to be 60% effective. Both vaccines were 33% effective after the first dose. While experts don’t believe this variant evades the vaccine immune response, other variants appear to be a little more slippery – we know they don’t work as well against the variant which first originated in South Africa. And there’s potential for more of these variants to crop up as the virus mutates, warranting new and improved vaccines. 

Dr David Matthews, reader in virology at the University of Bristol, predicts we’ll need a regular vaccine for the next few years to deal with any problematic variants that arise and to help people’s immune systems to remember the virus. But in the long-term, he thinks we won’t need an annual jab as our bodies will build up sufficient immune memory to fight the virus.

“Over your lifetime, you lay down an immune memory – so every disease you fight, you lay down a memory, to one degree or another, of that fight and what to do,” says Dr Matthews. “And that means when you meet the disease again, the chance is your immune system will remember the fight and will be responsive and faster – therefore the infection can’t do as much damage before the immune system can get on top of it.”

Dr Matthews theorises that the reason older people have been so impacted by the virus is because as you get older, your immune system relies more on memory. So, by the time your immune system has realised it can’t remember how to the fight Covid, the virus has snuck past it and wreaked havoc.

We need to build this collective immune memory – for everyone in the world – to remember the virus. And a few jabs, including a couple of boosters along the way to deal with new variants, could be enough to do that, he suggests. “What the vaccine does is it artificially creates immune memory for you,” he explains.

“The vaccine currently creates an immune memory designed towards what you might call ‘classic Covid’, which first emerged. The next set of vaccines they’re talking about, which are similar, will be based on the South Africa variant.

“So if you’ve had the classic vaccine, and then this autumn you get the South African version, and then maybe in a year’s time you get another version – after two or three goes with these vaccine variants, you’ll probably have a sufficiently broad immune memory that you’ll be able to deal with most variants that are ever going to come out. That’s my best guess.”

Ultimately, he believes Covid-19 will become like the common cold in terms of how it affects us and our immune systems will simply learn to bat it away.

Pfizer’s spokesperson says they can’t rule out seasonal vaccination just yet – but more data is needed on how long the vaccines offer protection for. “There is much to learn about the disease, the virus and the protective nature of the vaccines in development before coming to certain conclusions,” they tell HuffPost UK. “We don’t know how the virus will change, we also don’t know how durable the protective effect of any vaccination will be in the long term.”

Dr Matthews adds that those who don’t end up vaccinated may get it worse than their peers who’ve been vaccinated. “The key point here is the virus isn’t going to go away, you will meet this virus one day, and when you do you really do want to have the vaccine onboard first,” he says.

Experts are still learning about Covid-19. The information in this story is what was known or available at the time of publication, but guidance could change as scientists discover more about the virus. To keep up to date with health advice and cases in your area, visit gov.uk/coronavirus and nhs.uk.