TRIPLE SHOT
COVID vaccine efficacy could dip below what is considered an acceptable level of 50 per cent within months, an expert has warned.
Immunity against the virus is waning, data show, and the jabs are already weakened by the super-strain Delta.
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The ZOE Covid Symptom Study, led by King’s College London, has worked out how well jabs are protecting the population using data given by millions of the phone app users.
The team said today the Pfizer vaccine is 88 per cent effective a month after the second dose, but this drops to 74 per cent after five or six months.
Meanwhile, the AstraZeneca vaccine is 77 per cent effective a month after the second dose, reducing to 67 per cent at five months.
It supported a study last week that warned Pfizer’s protection was only 78 per cent after three months, and AstraZeneca was 61 per cent.
It means those who got their jabs first - the most vulnerable in society - may have much lower protection now and going into the autumn.
Experts are concerned the jabs will fail to protect up to half of cases come winter time.
Professor Tim Spector, lead scientist on the ZOE COVID Study app, said: “In my opinion, a reasonable worst-case scenario could see protection below 50 per cent for the elderly and healthcare workers by winter."
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Fifty per cent efficacy is the level at which a vaccine must reach in order to be approved for use in the first instance, according to the World Health Organization.
It comes after Prof Spector said on Friday the first sign of waning immunity may be that cases are no longer falling at speed.
Prof Spector said the data was no reason not to get the vaccine, as it still works strongly against the fast-spreading Delta variant, dominant in the UK.
But with “breakthrough infections” looking to become more likely, he urged for booster jabs.
“We urgently need to make plans for vaccine boosters, and based on vaccine resources, decide if a strategy to vaccinate children is sensible if our aim is to reduce deaths and hospital admissions,” Prof Spector warned.
Dr Alexander Edwards, Associate Professor in Biomedical Technology, University of Reading, commented the study did not analyse whether severe disease and death was increasing as a result of weaker immunity.
Nevertheless, he said: “We must proactively plan our public health strategy to account for imperfect protection, and for the possibility of falling protection over time.”
Dr Simon Clarke, Associate Professor in Cellular Microbiology, University of Reading, said it couldn't be teased out whether the rise in cases is due to waning immunity, or other factors.
He added: “The claim that immunity levels will hit around 50 per cent by Christmas is not based on any robust analysis of data, and seems more like a finger in the air prediction."
Prof Ian Jones, virologist at University of Reading, said it was "certainly possible" for jabs protectiveness to drop to 50 per cent.
But he said: "The need for boosters still needs to be balanced with global vaccine distribution to populations where even a first shot will lower virus circulation."
Israel’s warning
The effects of a booster campaign are already being seen in Israel, which has been facing a “deadly fourth wave” due to waning immunity and the Delta variant which reached there in June.
It’s infection rate reached among the highest in the world despite being a world leader in vaccinating its population.
Just one month after giving third shots to the over 60s, the R rate has fallen below the critical level “1” - meaning the outbreak is shrinking.
More than half of over 60s have received a third vaccine dose, according to Israeli health ministry data and scientists interviewed by Reuters.
Doron Gazit, a member of the Hebrew University's COVID-19 expert team which advises the government, said the rise in cases of severely ill vaccinated people in over 60s has been steadily slowing to a halt in the last 10 days.
“We attribute this to the booster shots and to more cautious behaviour recently," Gazit said.
The country is now calling over 30s up for their third dose - something which is not planned for the UK any time soon.
Experts say lessons must be learnt from Israel, amid predictions a “fourth wave” is likely to occur once schools and office-working returns in September.
Dr Clarke said: “Lessons from countries like Israel, where the majority of the population were vaccinated early in 2021, shows that a new wave of infections, driven by new more infectious variants, can still drive up infection rates quickly.”
Professor Eran Segal, of the Weizmann Institute in Israel, said it would be “wise to act now and prevent a deadly wave in the UK”.
He wrote for the Daily Mail: "There is no question that Israel – the country that led the way with a Covid vaccine roll out for its nine million population – is now experiencing a fourth wave of infections.”
Professor Lawrence Young, of Warwick University, said some are calling Israel "the canary in the mine".
Boosters for Brits
Other countries are now planning their own booster campaigns, including France, Germany, and the US.
But there is no consensus among scientists that a third dose is necessary, and the World Health Organization has said more of the world should be vaccinated with a first dose before people receive a third dose.
Earlier in the summer the NHS were told to plan for millions of Brits to get an extra vaccination in the winter.
The decision on whether this will go ahead is still in discussion, and an announcement is expected imminently.
But even if the boosters are slowing the pandemic's pace, it is unlikely to fend Delta off entirely.
Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, Respiratory Sciences, University of Leicester, said waning immunity was “not surprising” because the jabs were made against the original virus strain from Wuhan, in 2019.
“Whilst booster shots with the current generation of vaccines designed against the original Wuhan virus will boost levels of cross/reacting antibodies, overall, they will not be very effective against the Delta variant as they are not specific for this virus,” Dr Tang said.
“So the once the antibody levels drop again, the delta variant will break through.
“Unfortunately, we really need to develop updated vaccines against the delta virus, specifically, to maintain longer-lasting, specific immunity to this variant.”
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Professor Adam Finn, member of the Joint Committee on Vaccination and Immunisation (JCVI), said today giving an additional coronavirus jab to immunocompromised people "might serve a useful purpose".
It followed on from a study which showed that 40 per cent of immunocompromised people generate a lower antibody response to healthy adults.
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