Covid-19 roundup: South African variant trips up Pfizer/BioNTech, Moderna vaccines while EU seeks anti-variant contract clauses — report
As questions continue to swirl about the effectiveness of current vaccines against new variants of the coronavirus, a pair of letters to the editor confirm that those developed by Pfizer/BioNTech and Moderna appear to be able to protect against the UK variant but less efficacious when faced with the strain originating from South Africa.
Now that the first-generation vaccines’ efficacy against the original SARS-CoV-2 antigen has largely been established, some scientists have turned their attention to the questions of when, where and how they can be best deployed.
The South African variant has already raised global alarms after AstraZeneca’s Oxford-partnered vaccine was sidelined after it failed a small-scale analysis specifically measuring its efficacy against B.1.351.
Writing to the New England Journal of Medicine, two different groups reported similar findings about the serum neutralizing activity elicited by the Pfizer/BioNTech and Moderna shots.
From the letter on BNT162b2:
Thus, as compared with neutralization of USA-WA1/2020, neutralization of Δ242-244+D614G virus was similar and neutralization of the B.1.351-spike virus was weaker by approximately two thirds. Our data are also consistent with poorer neutralization of the virus with the full set of B.1.351-spike mutations than virus with either subset of mutations and suggested that virus with mutant residues in the receptor-binding site (K417N, E484K, and N501Y) is more poorly neutralized than virus with Δ242-244, which is located in the N-terminal domain of the spike protein.
Meanwhile with mRNA-1273:
Both the full panel of mutations in S and a subset of mutations affecting the receptor-binding domain (RBD) region of the B.1.1.7 variant had no significant effect on neutralization by serum obtained from participants who had received the mRNA-1273 vaccine in the phase 1 trial (Figure 1A and 1B). In contrast, we observed a decrease in titers of neutralizing antibodies against the B.1.351 variant and a subset of its mutations affecting the RBD.
In a third letter, two Canadian researchers suggest that the two doses of the Pfizer/BioNTech vaccine should be given at a longer interval than currently prescribed, based on a new analysis on the data both companies submitted to the FDA.
One dose of the vaccine, they argue, is actually higher than the 52.4% figure that Phase III investigators had originally thought. If you remove data from the first two weeks after the first dose, “when immunity would have still been mounting,” the efficacy would actually be much higher.
“Even before the second dose, BNT162b2 was highly efficacious, with a vaccine efficacy of 92.6%, a finding similar to the first-dose efficacy of 92.1% reported for the mRNA-1273 vaccine (Moderna),” they wrote. “Given the current vaccine shortage, postponement of the second dose is a matter of national security that, if ignored, will certainly result in thousands of Covid-19–related hospitalizations and deaths this winter in the United States — hospitalizations and deaths that would have been prevented with a first dose of vaccine.” — Amber Tong
EU seeking anti-variant contract clauses — report
With the emergence of new Covid-19 virus variants and uncertainty surrounding vaccines’ protection against them, the EU is reportedly looking to ensure access to potential booster shots in its deals with vaccine makers.
The bloc is adding anti-variant clauses to new vaccine supply contracts and seeking to amend its older deals, Reuters reported, with language that explicitly covers the variants. The negotiations come amid the publication of studies from Pfizer and Moderna that suggest lower antibody levels against the South African variant and South Africa itself halting rollout of the AstraZeneca/Oxford vaccine after it showed highly diminished efficacy fighting the variant in a small trial.
Three EU sources confirmed the news to Reuters, with one official saying the clauses would allow the bloc to focus on buying upgraded shots rather than vaccines that are not effective against the widespread variants. However, the source added the definition of “variant” in the new contracts remained vague, and it was unclear what legal power the contracts would give the EU.
All three confirmed that one of these clauses was included in the new EU contract with Pfizer and BioNTech signed earlier this month. The deal is expected to supply 300 million additional doses of the pair’s mRNA vaccine.
In total, the EU has secured deals to acquire roughly 2.6 billion vaccines from six companies, and is still negotiating with Novavax, Valneva and Moderna to purchase even more.
On Wednesday afternoon, Pfizer and Moderna published research in the New England Journal of Medicine saying their vaccines still offer enough protection to neutralize the South African variant, but produce significantly fewer antibodies in response. The study was conducted in a laboratory setting and it remains unclear whether the same response would be seen in real life. — Max Gelman
Mexico factory producing AstraZeneca shot almost fully upgraded
Mexico had been preparing to package and distribute the AstraZeneca/Oxford vaccine throughout Central America, but that process had been held up by necessary factory changes. Now, the country is almost ready to start.
The factory upgrade had been held up by a series of complex certification processes after health regulators could not determine whether the plant could safely produce Covid-19 shots, Reuters reported. On an inspection visit to the factory, which previously made flu shots, officials noted 185 “observations” that needed to be fixed.
“They almost had to make another factory,” Mexican foreign minister Marcelo Ebrard said at a government news conference, per Reuters. “You are talking about health, life … so you do have to be very strict in any medicine, with a vaccine more, and even more when the vaccine is so recent.”
Mexico had received at least two shipments of AstraZeneca’s active vaccine ingredient but had not finished producing doses of the shot. The factory is now expected to start shipping the doses by early April, Ebrard said.
With the backing of Mexican billionaire Carlos Slim, AstraZeneca had reached agreements with Mexico and Argentina to distribute their shots throughout the Central and South American regions. Mexico also is aiming to speed up its vaccine campaign, having imported 870,000 AstraZeneca shots from India on Sunday. — Max Gelman
For a look at all Endpoints News coronavirus stories, check out our special news channel.