• The B.1.617.2 variant is a new, highly transmissible, variant of concern first observed in India and rapidly spreading in the UK. Evidence on the effectiveness of COVID-19 vaccines in protecting against the B.1.617.2 variant is limited.
  • The UK has already secured more than 500m doses of different COVID-19 vaccines, five of which are at different stages of development. The UK Medicines and Healthcare products Regulatory Agency (MHRA) is currently reviewing the Johnson & Johnson/Janssen and the Novavax vaccines.
  • This is part of our rapid response content on COVID-19. You can view all briefings on COVID-19 vaccines produced by POST and the House of Commons Library in Vaccination and Covid-19.

With more than 61 million doses administered across the UK, including more than 23m second doses, data on the effectiveness of COVID-19 vaccines on virus transmission is increasing. This paper summarises current understanding about the effectiveness of COVID- vaccines against the new B.1.617.2 variant (first observed in India). It also describes the latest developments on vaccines currently secured in the UK.

What it is known about the effectiveness of COVID-19 vaccines against the B.1.617.2 variant (first observed in India)?

Scientists worldwide are constantly monitoring the emergence and spread of new SARS-CoV-2 variants (see previous POST’s rapid response SARS-CoV-2 virus variants: a year into the COVID-19 pandemic) and their effect on immunisation programmes (see previous POST’s rapid response Which SARS-CoV-2 variants reduce the effectiveness of vaccines?).

On 6 May 2021 PHE announced that the B.1.617.2 variant (a subtype of the B.1.617 lineage that was previously classified as a ‘variant under investigation’) became an official new variant of concern.

On 11 May 2021 the World Health Organisation (WHO) classified as variants of concern all three different variant subtypes within the lineage B.1.617 (B.1.617.1, B.1.617.2, B.1.617.3). These three subtypes have all been first observed in India. The North West (predominantly Bolton) and London are the areas with the highest rates of B.1.617.2 cases, with 706 and 650 cases respectively as of 22 May 2021.

During its 89thmeeting on 13 May 2021, SAGE concluded that it is highly likely that the B.1.617.2 variant is more transmissible than the B.1.1.7 variant (first observed in England). Moreover, given the difference between B.1.617.2 and the ‘wild type’ version of the virus identified in Wuhan (that is the ‘template’ for all the vaccine currently deployed in the UK), SAGE concluded that there could be some reduction in the ability of vaccines to protect against this new variant (especially against transmission, as protection against severe disease or death is less likely to be affected). More data and monitoring are needed to confirm these statements.

During this meeting SAGE also discussed a consensus briefing produced by SPI-M-O, which analysed the impact of the higher transmissibility of B.1.617.2 on infections, considering the planned lifting of restrictions and the potential of surge vaccination as a way to reduce infections by accelerating vaccine take-up among eligible groups in areas with a higher number of cases.

On 14 May 2021, the Joint Committee on Vaccination and Immunisation (JCVI) advised a series of measures to mitigate the impact of the B1.617.2 variant, including further promotion of vaccine uptake in unvaccinated priority groups and a reduction of the second dose delay from 12 to 8 weeks. The Government is currently implementing this, together with surge testing to control the spread in affected areas (see the House of Commons Library brief on Coronavirus variants and surge testing in England).

What is the latest evidence on COVID-19 vaccines and the B.1.617.2 variant?

Evidence on the effectiveness of COVID-19 vaccines currently deployed in the UK against the B.1.617.2 variant is very limited. There are a few pre-prints (not-peer reviewed studies) that analysed the ability of antibodies triggered by two doses of the Pfizer/BioNTech or the Moderna RNA-based vaccines to neutralise the spike protein found on the B.1.617 or B.1.617.1 variants. These preliminary studies found that antibodies triggered by the Pfizer/BioNTech or the Moderna RNA-based vaccines were still able to neutralise the B.1.617.1 variant, although an up to a 7-fold reduction in neutralising activity was observed.

One pre-print (not peer-reviewed) analysed the ability of antibodies triggered by the University of Oxford/AstraZeneca vaccine (known in India as Covishield) to neutralise the B.1.617.1 variant and found almost a 2-fold reduction in neutralising activity.

On 22 May 2021 PHE released a pre-print (not-peer reviewed) that evaluated the effectiveness of the Pfizer/BioNTech and the University of Oxford/AstraZeneca vaccines against the B.1.617.2  variant in comparison to the B.1.1.7 one(first identified in England). By analysing 12,675 sequenced cases in total, they found that both vaccines were 33% effective against B.1.617.2 infection three weeks after the first dose (compared to around 50% against B.1.1.7 infection). Two doses of the Pfizer/BioNTech vaccine were 88% effective against infection with the new variant (compared to 93% against B.1.1.7) while two doses of the University of Oxford/AstraZeneca were 60% effective (compared to 66% against B.1.1.7).

How close to the finish line are the other vaccines already secured by the UK?

In addition to the 217m doses of currently approved vaccines (100m of the University of Oxford/AstraZeneca vaccine, 100m of the Pfizer/BioNTech vaccine and 17m of the Moderna vaccine), the UK has secured an additional 300m doses of five COVID-19 vaccines candidates at different stages of development (a description of the different phases of preclinical and clinical trials are available in the POST COVID-19 glossary). These are:

  • 30 million doses of the Johnson & Johnson/Janssen vaccine (under rolling review for approval in the UK, already approved in the USA and EU)
  • 60 million doses of the Novavax vaccine candidate (under rolling review for approval in the UK)
  • 100 million doses of the Valneva vaccine candidate (in Phase 3 clinical trials)
  • 60 million doses of the GlaxoSmithKline (GSK) and Sanofi Pasteur vaccine candidate (in Phase 2 clinical trials)
  • 50 million doses of the CureVac vaccine candidate (in preclinical trials)

The Johnson & Johnson/Janssen vaccine

The Johnson & Johnson/Janssen vaccine is a single-dose vaccine based on similar adenovirus technology as the University of Oxford/AstraZeneca vaccine.

On 21 April 2021 results of a Phase 3 clinical trial involving almost 40,000 participants were published. They showed 66.9% efficacy against moderate to severe-critical COVID-19 at least 14 days after injection. A Phase 3 clinical trial testing a 2-dose regime of this vaccine in up to 30,000 participants worldwide is still in progress.

The Johnson & Johnson/Janssen vaccine has been already approved by the US Food and Drug Administration (FSA) and the European Medicines Agency (EMA). A rolling review by the UK Medicines and Healthcare products Regulatory Agency (MHRA) is currently underway (see more information about regulatory approval in POST’s Regulatory approval of COVID-19 vaccines in the UK).

A rare risk of developing blood clots following administration of the Johnson & Johnson/Janssen vaccine has been detected. This is described in more details in POST’s rapid response on COVID-19 Vaccines safety and blood clots)

The Novavax vaccine candidate

The Novavax vaccine candidate is a protein-based vaccine, that is using the spike-shaped protein found on the surface of SARS-CoV-2 to trigger an immune response. Preliminary data recently showed its efficacy against the B.1.351 ( first observed in South Africa) variant and the B.1.1.7 (first observed in England) variant. On 5 May 2021 results of Phase 2 trials were published. They showed safety and efficacy data from 4387 participants in South Africa who received at least one injection of the vaccine candidate or a placebo.

Preliminary data from 41 samples fully sequenced show that the Novavax vaccine candidate is 51.0% effective in preventing symptomatic COVID-19 caused by the B.1.351 variant in HIV-negative participants. A preprint (not peer-reviewed) paper analysing data from 15,187 participants in a UK-based phase 3 trial was released in 14 May 2021. Data showed that this vaccine candidate is 96.4% effective in preventing symptomatic COVID-19 disease caused by the wild-type version of SARS-CoV-2 and 86.3% in preventing symptomatic disease by the B.1.1.7 variant.

Novavax announced a series of developments regarding its vaccine candidate in the past few months:

Both the EMA and the MHRA are performing a rolling review of this vaccine candidate. According to the latest press release by the company, authorisation by the FDA, the EMA and the MHRA is expected in the third quarter of 2021.

The Valneva vaccine candidate

The Valneva vaccine candidate is an inactivated vaccine, where the virus has been killed and therefore cannot multiply in the human body.

On 6 April 2021, positive results from Phase 1/2 clinical trials were announced (although they are not publicly available yet). They showed a strong immune response and no safety concerns following vaccination in 153 healthy adults aged 18 to 55 years with three different dose levels of this candidate.

On 21 April 2021, the company announced the beginning of a phase 3 trial comparing the immune response triggered by its vaccine candidate with the one elicited by the University of Oxford /AstraZeneca vaccine. The study will involve 4,000 participants in the UK.  

The GSK Sanofi-Pasteur vaccine candidate

The GSK Sanofi-Pasteur vaccine candidate is a protein-based vaccine (similar to the Novavax candidate). On 17 May the results of Phase 2 clinical trials were announced from 722 participants enrolled in the US and Honduras. A Phase 3 trial is expected to start in the coming weeks and will enrol more than 35,000 adult participants worldwide.

The CureVac vaccine candidate

On 5 February 2021, the UK Government announced a collaboration with the Germany-based company CureVac for the production of a new RNA based vaccine against SARS-CoV-2 variants.

On 13 May 2021 a press release from CureVac announced positive results from preclinical trials. These results are currently published as a pre-print (not-peer reviewed) study. The study found high levels of neutralising antibodies against the B.1.1.7 (first observed in England) and B.1.351 ( first observed in South Africa) variants in rats immunised with this new vaccine RNA vaccine candidate.


POST would like to thank Professor Adam Finn (University of Bristol; Bristol Royal Hospital for Children) who acted as external peer reviewer in preparation of this article.

Image of Covid Vaccination Centre by Tim Dennell, under CC BY-NC 2.0

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