Two Pfizer vaccines over 95% effective against Kent coronavirus variant, Israeli study suggests

·9 min read
A doctor is giving a flu vaccine for illness prevention.
The results highlight the importance of having both vaccine doses when called up. (Stock, Getty Images)

Receiving both doses of the Pfizer-BioNTech coronavirus vaccine is more than 95% effective against the variant that is thought to have emerged in Kent, research suggests.

The UK has three jabs in its immunisation arsenal – Pfizer-BioNTech, University of Oxford-AstraZeneca and Moderna. All were approved after studies demonstrated they prevent severe disease caused by the variant that arose in Wuhan, China, where the outbreak was identified at the end of 2019.

While an effective vaccination programme has long been hailed as a route out of the pandemic, the emergence of variants in South Africa, California and India – to name a few locations – has left many concerned the virus may no longer respond to the jabs.

With most confident the vaccines will be at least somewhat effective, scientists from Imperial College London recently flagged one Pfizer-BioNTech dose may only offer "significantly enhanced protection" against the Kent and South Africa variants in people who have naturally overcome the Wuhan variant.

Read more: One in 14 in hospital with COVID had first vaccine

Writing in The Lancet, scientists from Israel's Ministry of Health have now revealed two doses of the vaccine were more than 95% effective against infection, hospitalisation and death when the Kent variant was dominant, as it is in the UK.

Overall, a single jab was found to protect against infection, hospitalisation and death by 58%, 76% and 77%, respectively – highlighting the importance of taking up both doses when called.

Young woman wearing surgical mask in front of home
Effective vaccines could free people from the constraints of face coverings. (Posed by a model, Getty Images)

"As the country with the highest proportion of its population vaccinated against COVID-19 [the disease caused by the coronavirus], Israel provides a unique real-world opportunity to determine the effectiveness of the vaccine and to observe wider effects of the vaccination programme on public health," said lead author Dr Sharon Alroy-Preis.

"Until this point, no country in the world had described the national public health impact of a nationwide COVID-19 vaccination campaign. 

"These insights are hugely important because, while there are still some considerable challenges to overcome, they offer real hope COVID-19 vaccination will eventually enable us to control the pandemic."

Read more: Sore arm most common coronavirus vaccine side effect

On 24 April, Israel recorded no coronavirus-related deaths for the first time in 10 months. This has been attributed to its speedy vaccination programme, with about 120 doses being administered per 100 people – the highest rate among countries with a population of at least one million.

Israeli officials have suggested the country is edging towards herd immunity, with the World Health Organization (WHO) estimating around 70% of residents need to be vaccinated to prevent the coronavirus taking hold in a community.

Watch: Do coronavirus vaccines affect fertility?

Rising coronavirus numbers prompted Israeli officials to introduce a nationwide lockdown on 27 December, which was lifted on 7 March. Infection incidences peaked on 20 January with 10,213 cases. 

The Pfizer-BioNTech vaccine was the only jab rolled out in Israel from 24 January to 3 April, the Ministry of Health's study period.

More than seven in 10 (72%) people over 16 years old and nine in 10 (90%) older than 65 had received both Pfizer-BioNTech doses by 3 April.

Over the study's 10-week period, national surveillance data indicate how receiving two doses of the jab compared against coronavirus infections, hospitalisations and deaths.

Read more: Everything we know about India's coronavirus variant

The participants, who were analysed according to their age, were followed for around 48 days after their second jab.

Over the study period, 232,268 confirmed coronavirus cases arose. The Kent variant, also known as B.1.1.7, accounted for more than nine in 10 (94.5%) of the incidences tested through Israel's free polymerase chain reaction (PCR) swabbing service, considered the gold-standard of diagnosis. 

Two-thirds (66%) of the cases were in people over 16, who made up the study's participants.

Overall, there were 7,694 hospital admissions – of which 4,481 were considered severe and 188 were critical – and 1,113 deaths.

In the first nationwide study into the Pfizer-BioNTech vaccine's effectiveness, the Ministry of Health scientists have concluded the jab is "highly effective" after two doses.

The vaccines offered 95.3% and 96.7% protection against infection and death, respectively, seven days after the participants' second dose, the results show. 

The vaccine was approved after a study demonstrated it wards off COVID-19, however, it was less clear whether the jab prevents the infection itself.

The Ministry of Health scientists found the two-dose regimen offered 97% and 91.5% protection against symptomatic and asymptomatic infections, respectively. 

Around a third of people who catch the coronavirus are thought to develop no symptoms. Many may therefore be unaware they need to get tested and isolate, causing them to unwittingly spread the infection.

Read more: Predicting the next pandemic 'harder than we think'

Speaking of the asymptomatic result, Dr Peter English – former editor of Vaccines in Practice magazine – said: "This is extremely reassuring. It means vaccination does have the potential to induce herd immunity".

Receiving both doses of the Pfizer-BioNTech vaccine was found to give 97.2% and 97.5% protection against overall hospitalisations and admissions that were severe or critical, respectively.

At day 14 post-jab, protection against infection, hospitalisation and death was recorded at 96.5%, 98% and 98.1%, respectively. 

It is unclear how long the immune response lasts, with more data due in time.

Unable to marshal the right cells and molecules to fight off the invader, the bodies of the infected instead launch an entire arsenal of weapons — a misguided barrage that can wreak havoc on healthy tissues, experts said. (Getty Images)
Early research suggests the coronavirus is mild in four out of five cases, but can trigger a disease called COVID-19. (Stock, Getty Images)

Elderly people are significantly more likely to become seriously ill and die with the coronavirus. They also tend to have a more muted immune response after overcoming an infection or being vaccinated.

The Ministry of Health scientists found the study's elderly participants were as protected post-jab as their younger counterparts.

Those over 85 had 94.1%, 96.9% and 97% protection against infection, hospitalisation and death, respectively, seven days after receiving their second dose. The participants aged 16 to 44 had 96.1%, 98.1% and 100% protection, respectively.

Israel's coronavirus infections rose among people older than 65 until mid-January, peaking at around 55 cases per 100,000 people.

This started to decline as people had their second dose, with daily cases of around 30 per 100,000 by Israel's first reopening phase on 7 February. 

The Ministry of Health scientists have observed the decline in infection rates was more pronounced among people over 65, likely reflecting the higher and earlier vaccination rates in older age groups. 

Speaking of the study, Professor Jonathan Ball, from the University of Nottingham, said: "This is why it is important people get both doses and if UK vaccine policy changes to get a third dose if offered in the autumn.

"Topping up your immunity with the vaccine boost will be even more important with the emergence of new variants that might have acquired genetic changes that make them more resistant to the immunity generated by vaccines or following natural infection."

Watch: What is long COVID?

The Ministry of Health scientists have stressed the participants were considerably less protected between seven and 14 days after their first dose, compared to receiving both jabs.

Overall, receiving just one vaccine was linked to 57.7%, 75.7% and 77% protection against infection, hospitalisation and death, respectively.

"This population study provides something for everyone," said Dr Gillies O'Bryan-Tear, from the Faculty of Pharmaceutical Medicine.

"For those who have been critical of the UK stance of providing first doses to as many as possible and delaying the second dose, the results show people need to receive the second dose for full effectiveness.

"On the other hand, proponents of the delayed dosing policy can also draw comfort from the fact that even single dose effectiveness was substantial for the severe endpoints of hospitalisation and death".

It is unclear how long one jab protects against the coronavirus compared to both doses.

A single vaccine may provide a shorter window of protection, particularly as new variants emerge, the scientists have warned.

"As vaccination programmes continue to ramp up around the world, more data is needed urgently about the effectiveness of the Pfizer-BioNTech vaccine against severe disease and death, and about the levels of protection it provides to elderly people," said Dr Luis Jodar, from Pfizer. 

"Research examining long-term vaccine effectiveness will ultimately play a vital role in tackling the pandemic."

The Ministry of Health scientists have stressed countries differ in how vaccines are being rolled out, as well as how their individual coronavirus outbreak is evolving. Additional studies into the Pfizer-BioNTech vaccine, and other jabs, are therefore required.

The South Africa variant – B.1.351 – has recently been identified in Israel, but was not included in the Ministry of Health analysis.

The scientists did not account for the participants' ethnicity, socioeconomic status or likelihood of getting tested for the coronavirus, all of which can influence a person's risk. 

Writing in The Lancet, Professor Eyal Leshem, from Israel's Chaim Sheba Medical Centre, and Professor Annelies Wilder-Smith, from the London School of Hygiene & Tropical Medicine – neither of whom were involved in the study – said: "[The] findings from Israel suggest high vaccine coverage rates could offer a way out of the pandemic. 

"Regrettably, rapid population-level coverage cannot be easily replicated in many other countries. 

"The global use of BNT162b2 [the Pfizer-BioNTech] vaccine is limited by supply issues, high costs and ultra-cold chain storage requirements.

"Israel's experience provides impetus for countries to proactively pursue high vaccine coverage to protect the population, however, rollout would need to follow the WHO prioritisation roadmap to maximise the public health impact, in light of vaccine supply constraints. 

They added: "More post-introduction vaccine effectiveness studies will be required. 

"Timely reporting of vaccine effectiveness against variants of concern, the duration of protection across age groups and geographical settings, and the effectiveness of alternative dosing regimens is crucial to provide data-driven immunisation policies."

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