Pfizer, BioNTech file for FDA approval of COVID booster shot

Pfizer and BioNTech have formally asked for FDA approval of a third dose of their COVID-19 vaccine BNT162b2 in people aged over 16, as the US prepares to get its booster campaign underway.

The two companies have submitted data from a phase 1 trial in support of the booster dose to the US regulator, and will follow that with filings in Europe and elsewhere in the world in the coming weeks.

The move comes a few days after both the FDA and the Centres for Disease Control and Prevention (CDC) cleared emergency use of third doses of either the Pfizer/BioNTech or Moderna COVID-19 vaccines for people with "moderately to severely" weakened immune systems as well as solid organ transplant recipients.

Mixing of the two mRNA vaccines is permitted for the third shot if the original vaccine received by a person is not available, according to the agency.

The results of the safety and immunogenicity study show a favourable safety profile and "robust" immune responses after a third dose, said Pfizer and BioNTech in a statement.

"The data we've seen to date suggest a third dose of our vaccine elicits antibody levels that significantly exceed those seen after the two-dose primary schedule," said Pfizer chief executive Albert Bourla.

The study involved adults who had received two doses of BNT162b2 in the original phase 1 trials of the shot, and were then given a third dose between eight and nine months later.

According to the companies, the third dose stimulated significantly higher neutralising antibodies against the original 'wild-type' SARS-CoV-2 virus than after the two-dose regimen, as well as against the beta variant and the highly infectious delta strain.

"Vaccination is our most effective means of preventing COVID-19 infection – especially severe disease and hospitalisation – and its profound impact on protecting lives is indisputable," continued Bourla.

"Still, with the continuing threat of the delta variant and possible emergence of other variants in the future, we must remain vigilant against this highly contagious virus," he added.

Data from a larger phase 3 study of the third dose is also expected shortly and will be submitted to the FDA when available, said the drugmakers.

CureVac, GSK say new-generation jab is much improved

There was also encouraging news for CureVac and GlaxoSmithKline's COVID-19 vaccine programme, after the two partners said a new, improved version of their shot was much better at protecting against the virus in preclinical testing than their first effort.

Their first mRNA-based candidate was found to be just 47% effective in a phase 3 trial reported in June, below the threshold efficacy level for a vaccine laid out by the World Health Organisation (WHO) in the early stages of the pandemic and well short of rival shots.

The new CV2CoV version – which achieved "faster response onset, higher titres of antibodies, and stronger memory B and T cell activation" than its predecessor – is set to start human testing in the fourth quarter of this year.

It is designed to simultaneously tackle multiple variants of SARS-CoV-2, including beta, delta and lambda – which some studies suggest is even more transmissible than delta.

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