Pfizer says vaccine only slightly less effective on S African variant

Pfizer's Covid-19 vaccine is only slightly less effective against the South African variant of the virus, a study in the US has found.

The study by Pfizer and scientists from the University of Texas Medical Branch (UTMB), which has not yet been peer-reviewed, showed a less than twofold reduction in antibody titer levels, indicating the vaccine would likely be effective in neutralising a virus with the so-called E484K and N501Y mutations found in the South African variant.

The news comes just a day after the Irish Government announced tough new restrictions on travel from South Africa and Brazil. This include the temporary ban on visa-free travel to Ireland from these countries.

Travellers from South Africa will face mandatory hotel quarantine on arrival in Dublin regardless of the result of any PCR test under the rules as Ireland and other countries fear the impact of the South African variant of the virus on efforts to control the third wave of the pandemic.

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Moderna on Monday said lab studies showed antibodies made in response to its vaccine were six times less effective at neutralizing a lab-created version of a South African variant than prior versions of the virus.

The Pfizer study was conducted on blood taken from people who had received the vaccine. Its findings are limited because it does not look at the full set of mutations found in the new South African variant.

While these findings don’t indicate the need for a new vaccine to address the emerging variants, Pfizer and BioNTech are prepared to respond if a variant of SARS-CoV-2 shows evidence of escaping immunity by the COVID-19 vaccine, the companies said.

The scientists are currently engineering a virus with the full set of mutations and expect to have results from that in around two weeks, according to Pei-Yong Shi, an author of the study and a professor at UTMB.

The results are more encouraging than another non-peer-reviewed study from scientists at Columbia University earlier on Wednesday, which used a slightly different method and showed antibodies generated by the shots were significantly less effective against the South Africa variant.

One possible reason for the difference could be that the Pfizer findings are based on an engineered coronavirus, and the Columbia study used a pseudovirus based on the vesicular stomatitis virus, a different type of virus, UTMB’s Prof Shi said. He said he believes that finding in pseudoviruses should be validated using the real virus.

The study also showed even better results against several key mutations from the highly transmissible UK variant of the virus. Prof Shi said they were also working on an engineered virus with the full set of mutations from that variant as well. – Reuters