Pfizer and BioNTech coronavirus vaccine gets boost from German data.
Pfizer and BioNTech released data Monday from an early German-based study of its coronavirus vaccine BNT162b1 showing for the first time that it stimulated a virus-specific response from immune cells as well as antibodies. Earlier this month the partners published the results of a trial in U.S. patients that only examined levels of antibodies to SARS-CoV-2.
Release of the data came only hours after Pfizer and BioNTech signed a deal to supply 30 million doses to the U.K. In total, some 100 million doses are expected to be manufactured by the end of 2020 and 1 billion by the end of 2021.
Pfizer and BioNTech are expected to be among the first companies, alongside Moderna and AstraZeneca, to begin late-stage tests to determine whether their coronavirus vaccine can prevent infections or symptomatic disease. Widespread vaccination is believed to be essential to establishing the "herd immunity" that will keep the virus in check in the future.
While the German trial of BNT162b1 in healthy volunteers was the first to get started, it was later than the U.S. trial in generating an initial publication on the medical pre-print server Medrxiv. The data have yet to be peer-reviewed. And as a Phase 1 trial measuring safety and biological responses in just 60 patients, it's not possible to say whether the vaccine will prevent coronavirus disease. Researchers don't yet know what level of immune response will protect people from infections or severe cases of COVID-19.
The participants received a prime injection and a boost three weeks later, except for those in the highest dose group of 60 micrograms, who received just one.
The trial revealed that at doses of between 1 and 50 micrograms, the vaccine stimulated a response from virus-fighting T cells that can target the coronavirus' signature "spike" protein. That response was identified in most of the 36 patients tested a week after the booster shot.
Of the 36, 34 saw a response from T cells called CD4 positive, which are important in mounting a broad immune attack and establishing the "memory" that can lead to lasting protection. Meanwhile, 29 saw a response in the form of T cells called CD8 positive, which help to clear infected cells.
The T cell response will come as some comfort to the partners, as vaccine rival Moderna's MRNA-1273 managed to stimulate CD4 positive T cells but only low levels of CD8s.
Data from the German trial also backed up the antibody findings of the U.S. trial. In the patients receiving shots of 50 micrograms, neutralizing antibody levels measured three weeks after the boosting dose were more than three-fold higher, on average, than those in patients who have been infected with the virus. At the 1 microgram dose, antibodies only rose a mean of 0.7 that of the coronavirus patients, but the antibody responses were higher with each rising dose.
Moderna reported its shot stimulated neutralizing antibody levels two to four times those seen in infected patients. Comparing each against the other, however, is difficult because of the differences between the tests each group uses.
Pfizer and BioNTech's supply deal adds 30 million doses to the U.K.'s vaccines armory. Pfizer and BioNTech did not disclose terms of the deal, other than to say that payments would be "based on the timing of delivery and the volume of doses."
The U.K. has already signed a deal with AstraZeneca to supply 30 million doses of its shot by September, meaning Monday's deal will add enough vaccine doses to cover nearly all of the U.K.'s population of 68 million.