Coronavirus Variants: How Effective Are AstraZeneca, Janssen and Pfitzer Vaccines?

Do Covid 19 vaccines also work on variants? Several studies are underway around theworld to answer this question. At the moment the vaccines appear to be fully effective on theKent variant, while for the South African and Brazilian there may be a decrease ineffectiveness.

There are three variants that are closely monitored by the worldwide health organisations. Inall three cases the virus presents mutations on the so-called spike protein, which is the onewith which the virus attaches itself to the cell.

The Kent (UK) variant​ was isolated for the first time in September 2020 here in the UK,while in Europe the first case detected dates back to November 9, 2020. It is monitoredbecause it has a higher transmissibility, also hypothesized a greater pathogenicity, but thereis currently no evidence of a negative effect on the efficacy of vaccines.

The South African variant​ was first isolated in October 2020 in South Africa, while inEurope the first case detected dates back to December 28, 2020.

The Brazilian variant, ​the most recent one​, ​was first isolated in January 2021 in Brazil and Japan. As of January 25, 2021. It is monitored because it has a higher transmissibility and while studies show that vaccines work very well on the english variant as for the originalcoronavirus, both the South African and Brazilian variants are now under the loop because ithas a higher transmissibility and the results of the effectiveness of the vaccines are not so reassuring.

Studies from trials that also took place in South Africa show that:

  • Novavax: 89% efficacy in UK vs 60% in South Africa
  • Janssen: 72% efficacy in the US but 57% in South Africa

Despite the drop in effectiveness, new research shows both vaccines still protect againstsevere disease, hospitalisation and death.

According to a laboratory study conducted by the United States, at the University of TexasMedical Branch, the Pfizer Inc and BioNTech vaccine was effective in neutralizing the viruswith the so-called N501Y mutation of the spike protein.

But the results are currently limited, as the full range of mutations found in the rapidlyspreading new variants of the virus has not been examined.

The Kent variant has come to touch 38% in the Paris region and the English and SouthAfrican variants would constitute 20% of the contagion in Germany.

Not the best news but at least the World Health Organization (WHO) said it was “optimistic”as the Kent variant seems to be under control, “Over the last couple of months we’ve seenvery similar efficacy of the Oxford AstraZeneca vaccine against the B117, UK, or Kentvariant, very similar to the original virus that was circulating last year.” says Andrew Pollard,professor of paediatric infection and immunity, and chief investigator on the Oxford vaccine trial.

Further analysis revealed, by comparing the viral load in those who took the jab and thosewho did not, that those who received the Oxford jab but still became infected shed the virusfor a shorter time and had a lower viral load than those in the control group. The findingsmay help to explain why the vaccine appears to reduce transmission by as much astwo-thirds after people have had one dose.

Danny Altmann, a professor of immunology at Imperial College London, said the findingswere positive. “By any standards this is very good news as the B117 variant with itsincreased transmission had the potential to derail our planned timeline for recovery”.

Meanwhile, in order to place further security checks and promptly identify the variants,travelers entering the UK from 15th February will be required to carry 2 other swabs (after 2and 8 days from entry), in addition to the one at departure, for anyone authorized to travel orreturn to the UK.

Better get ready: If you are looking for healthcare staff for vaccine administration in your hub or hospital, we can help you to recruit the best people in the UK – contact us today on 0207 268 6230 or email

Image credit: Ascannio –