US Buys 100m Extra Pfizer Vaccine Doses As Study Reveals COVID-19 Variant Impact

Pfizer's COVID-19 vaccine could be unexpectedly effective against the new, potentially more virulent versions of the coronavirus, with the possible good news arriving as the pharma company confirms a big increase in orders from the US government. The extra purchase adds 100 million more doses of the Pfizer-BioNTech COVID-19 vaccine to the order books, taking the total number of doses to be supplied to 300 million.

The agreement between the US government and Pfizer had always allowed for that potential increase. Arranged on the assumption that the vaccine candidate would be granted emergency use authorization (EUA) by the US Food and Drug Administration (FDA), it means that the US will pay $1.95 billion for the extra doses.

Given Pfizer recommends that individuals get two doses in order to be as protects as is possible, that means sufficient supplies to vaccinate up to 150 million people. The US is also using Moderna's COVID-19 vaccine for its immunization roll-out.

At the same time as that is underway, however, concerns have heightened about the growing prevalence of so-called COVID-19 mutations. These variants of the coronavirus, typically known for the country in which they were first identified in the wild, are not necessarily more dangerous in terms of potential deaths than the original strain first spotted. However they can in some cases be more virulent and thus spread more rapidly, raising the possibility of greater impact on at-risk communities.

A new study on the Pfizer vaccine has suggested that efficacy of the drug on some of the newly-identified variants is strong. Immune response – measured both by antibody and by T-cell action, the latter of which destroy the body's infected cells and help produce antibodies against future infection – was less effective than for the original COVID-19 virus when faced with the UK B1.1.7 strain and South Africa B1.351 strain, however there was still a positive impact.

The study, carried out by researchers at the University of Oxford in the UK, is currently released in preprint. It has not yet completed peer review.

Key, though, is getting those two doses. "The results emphasize the need to generate high potency immune responses through vaccination in order to provide protection against these and other emergent variants," the researchers conclude. "We observed that two doses of vaccine also induced a significant increase in binding antibodies to spike of both SARS-CoV-1 & MERS, in addition to the four common coronaviruses currently circulating in the UK."

The need to deliver both doses of the vaccine has become a controversial one, as governments and healthcare authorities attempt to make the most effective use of limited stockpile of drugs. Pfizer, for example, advises patients be given two doses of its vaccine, 18-28 days apart; Moderna's has a similar dose regimen.

"There are no data available on the interchangeability of the Pfizer-BioNTech COVID-19 Vaccine with other COVID-19 vaccines to complete the vaccination series" Pfizer cautions. "Individuals who have received one dose of Pfizer-BioNTech COVID-19 Vaccine should receive a second dose of Pfizer-BioNTech COVID-19 Vaccine to complete the vaccination series."