Waning Covid Immunity This Winter: Your Questions Answered -

The UK coronavirus vaccine rollout started in December 2020 and the UK government has been quick to claim it’s one of the best in the world.

Certainly, it’s the biggest inoculation programme the country has ever run. So far in the UK, 50 million people have had a single dose of the vaccine and 45 million have had both doses. A single dose is also being offered to 12- to 17-year-olds though younger people seem slower or more reluctant to get a jab.

However, with cases, hospitalisations and deaths rising – Covid cases hit the highest they’ve been since the start of the pandemic last week – serious questions have been asked about immunity and how much it is waning.

Dr Susan Hopkins, chief medical adviser at the UK Health Security Agency, told the BBC’s Andrew Marr Show on Sunday: “We’re still seeing deaths in mainly the unvaccinated population… but increasingly, because of immune waning effects, there are deaths in the vaccinated group as well.”

The majority of those deaths are among older people, she said, particularly the over-70s, as well as among the clinically vulnerable and those with underlying health conditions.

“As we’ve mentioned, the immune effects wane and what we see is, especially in the older or the vulnerable groups, those are the people whose immunity will wane the most,” said Dr Hopkins. “So, if you’re a healthy 30-year-old, then two doses will protect you for a longer period. That’s why [older and vulnerable] people need to come forward for their third dose as soon as possible.”

Booster jabs are one of the key elements of the government’s winter plan. Over 50s are being prioritised to receive the booster jab first, along with anyone who is clinically extremely vulnerable, or aged 16 to 65 in an at-risk group.

With delays reported on the rollout and six months passed from many people’s second jabs, here’s what you need to know about the ‘immunity gap’ between vaccines and boosters.

How long do Covid vaccines protect us?

From early on, scientists knew the efficacy of the three main vaccines was likely to wane around six months after a person’s second dose, prompting clinical trials for booster jabs over the summer and plans for an autumn rollout.

Data from the Zoe Covid Study app, which invites users to log Covid-19 vaccines to monitor their side-effects and effectiveness, also points towards the waning of protection provided by two doses of the Pfizer/BioNTech and Oxford/AstraZeneca coronavirus vaccines within the six month period.

Analysis of app data suggested the Pfizer jab was 88% effective at preventing Covid-19 infection a month after the second dose but after five to six months, protection decreased to 74%. The AstraZeneca vaccine offered 77% protection against infection one month after the second dose but after four to five months, protection decreased to 67%.

“Waning protection is to be expected and is not a reason to not get vaccinated,” Professor Tim Spector, lead scientist on the app, said in August. However, he has since stressed that a precise plan is needed for booster jabs in particular.

“If you have had a natural infection and two jabs, it’s essentially like already having your booster,” Prof Spector told Sky News. “We need a much more precise way of giving boosters if it is going to be effective.”

An estimated 30 million people across the UK will be eligible for a third booster vaccine – starting with those in the priority groups at greatest risk from Covid. So far, almost 10 million people in the UK have received a booster.

Professor Neil Ferguson, from Imperial College London, has already urged the need for speed in the rollout (as well as vaccinating 12- to 17-year-olds).

“We have lower functional immunity in our population than most other Western European countries and that’s for two reasons,” he told the BBC’s Today programme. “Partly, we were very successful in getting vaccination rolled out early and we know that gradually immunity wanes over time after you’ve had that second dose, so how early we were means we are a bit more vulnerable.”

John Roberts from the Covid-19 Actuaries Response Group says the shortfall in the number of people eligible for their booster who have not yet received one has been growing by about 800,000 a week.

Also speaking to the Today programme, Roberts said: “If you project [the data] forward, then it’s going to probably take us well into January before we get through those first priority groups.

“At the start of the booster campaign, the health secretary Sajid Javid said: ‘We will protect the most vulnerable through the winter months’. But at the current rate it is going to be well through winter before we get through those first groups.”

KoldoyChris via Getty Images

When can younger people expect to get a booster?

The Joint Committee on Vaccination and Immunisation (JCVI) has so far given the green light for booster jabs to be delivered to over-50s, frontline healthcare workers, care home workers and residents, and some clinically vulnerable people and their families who are considered at a high risk from Covid infection.

Those under the age of 50 are unlikely to be offered a booster jab anytime soon as the NHS is struggling to get those who are eligible to take the jab. Asked when under 50s will be given the jab, a member of the JCVI told the i: “We haven’t discussed it yet and I think it would probably be well after Christmas.”

They added: “When you think about how long ago most of these people had [their second jab], they’re still within the six-month range. And bearing in mind a lot of people will have had Covid – they’re essentially tripled covered.”

How long does ‘natural’ immunity from Covid last?

Coronavirus antibodies from natural infection can last for at least six months for the majority (88%) of people who have had the virus, according to a UK Biobank study. Researchers said the results indicated antibodies produced following natural infection may “provide a degree of protection for most people”.

However UK Biobank chief scientist, Professor Naomi Allen says we can’t be certain how having these antibodies relates to immunity.

And levels of natural immunity might vary among the population. According to new analysis from the Zoe Covid Study app, 81% of participants who took an antibody test after a known Covid-19 infection tested positive for anti-N antibodies – the antibodies acquired from a natural infection, not vaccination.

But 19% of participants, or one in five, who had a previous infection, tested negative for anti-N antibodies. This means they could be at increased risk of future Covid-19 infection compared to those who had developed antibodies, and potentially at the same level of risk as those who haven’t been infected.

Should we be worried about the ‘immunity gap’?

Immunity to infection is waning among the UK population, this much is clear, and the current vaccines are not as effective at preventing infection from the Delta variant, says Professor Paul Hunter, an expert in infectious diseases at the University of East Anglia. But he stresses that immunity to severe disease is more robust after vaccination – and just as effective at preventing severe disease from Delta.

“The primary goal of vaccination was always to reduce risk of severe disease. Vaccination was never going to achieve herd immunity,” he tells HuffPost UK.

“So, no, not everyone needs a booster, at least yet, only those most likely to suffer more severe illness. Also if we did start to offer boosters to all, that would further delay vaccination for people in less wealthy countries who really need their first course.”

Dr Julian Tang, an honorary associate professor and clinical virologist at the University of Leicester, agreess that booster jabs are important but echoes Prof Hunter’s view that we need to focus on increasing global rates of vaccination.

“From a virological viewpoint, in general, boosters always help to reinforce and enhance vaccine immunity,” he tells HuffPost UK. “But we also need to increase vaccine coverage across the world as well – to reduce the generation of new variants that may include some with higher transmissibility, lethality, and vaccine escape properties than Delta.”

How can we best protect ourselves for now?

Dr Tang says we need to remain vigilant. Maintaining some degree of masking and social distancing like other EU countries is important, he says, “to control the virus at a NHS-manageable level, whilst vaccine boosters are rolled out to the most vulnerable people.”

As he sees it, “dropping all masking and social distancing restrictions on July 19 was predictably going to result in what we are seeing now with higher indoor mixing rates with larger crowds in the UK, which is likely to get worse towards Christmas – as we saw last year.”

Prof Hunter adds that we need to be as vigilant of flu as we are of Covid.

“What keeps me awake at night more than Covid going up is a flu epidemic this winter whilst we still have a lot of Covid around,” he says. “The Sars-CoV-2 virus is becoming endemic and will be around forever but end up like the other coronaviruses – becoming one of the causes of the common cold. Although hospitalisation rates have been flat declining for some time, they may be starting to drift up, and that is a worry.”

So his advice is to get the booster jab now if you are in one of the older or vulnerable groups. “Even if you are not in the above group, if you are called up. make sure you get your booster,” he adds. “Also, if offered, your flu jab.”

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