A bottle of the AstraZeneca vaccine.

Igor Petyx | KONTROLAB | LightRocket via Getty Images

Health analysts welcomed AstraZenecaThe results of the much-anticipated late-stage US study results for the Covid-19 vaccine.

The study of more than 30,000 participants in the US, Peru, and Chile found the vaccine to be a Overall effectiveness of 79% in preventing symptomatic Covid and 100% effectiveness in preventing serious illness and hospitalization.

Efficacy was consistent across ages and races, with 80% effectiveness in participants 65 and over. Known as AZD1222 and jointly developed with Oxford University, the vaccine was well tolerated and the independent data security watchdog did not find any security concerns related to the vaccine, the company said Monday.

The data exceeded expectations

In a research note, Jefferies health analyst Peter Welford described the data as “surprisingly positive”.

Adam Barker, Health Analyst at Shore Capital, said, “This is arguably the first study for AZD1222 that has shown convincing efficacy in those 65 years and older.”

This is important as there have been questions about its effectiveness in this age group. Previous studies have been hampered by fewer older participants. In this study, 20% of participants were 65 years of age or older and 60% had comorbidities, which placed them at increased risk of developing serious illnesses.

Monday’s trial data confirmed the vaccine’s safety profile. Barker said that having the data from a single study with a single-dose regimen removes the data interpretation complications seen in the past with the AstraZeneca-Oxford vaccine.

Barker added that the lack of evidence of blood clots in the study was also comforting in light of recent concerns. “We are not surprised by these data, however, as the evidence of a link between the vaccine and the blood clots was already quite weak.”

AstraZeneca said it will continue to analyze the data and prepare for the primary analysis to be submitted to the U.S. Food and Drug Administration for emergency approval in the coming weeks. The vaccine has already received conditional marketing or emergency marketing authorization in more than 70 countries on six continents.

Dosing regimen a key issue for the FDA

“I can’t understand why the regulator wouldn’t approve this,” Barker wrote, but warned that the detailed data is pending.

A key question for the FDA will be what dosage regimen it will endorse should it end up using the vaccine in an emergency.

“This study is based on dosing 4 weeks apart, but we know The effectiveness can be higher if you dose with a longer interval (up to 12 weeks) and countries like the UK have successfully used this “longer period between doses” strategy to vaccinate more people quickly, “Barker said.

So the question for the FDA is whether it will recommend giving the two doses four weeks apart – assuming this was tested in the US study – or including data from the UK and other countries suggesting a longer duration .

Welford also noted the sub-optimal dosing regimen used in this study. “The study evaluated the 4-week dosing schedule, but we have evidence that the vaccine works better with longer dosing intervals,” he said.

“The primary analysis of the UK, Brazil and South Africa Phase III clinical trials found 62% efficacy when the vaccine was given 4 to 12 weeks apart, but efficacy increased to 82% when the interval was 12 weeks has been extended. “”

In addition to the dosage, analysts also observe in detail how the vaccine protects against different variants. This is expected to be included in the data packet that will be submitted to the FDA.

When it comes to comparing today’s efficacy data with that of some other vaccine manufacturers, Welford has been warning since the first vaccine readings from Pfizer and ModernCovid-19 variants have become more and more common, so the effectiveness data for the different vaccines cannot be directly compared.

Barker added that the trial results gave the vaccine important validation. “Because of its cost and ease of storage and distribution, AZD1222 was once dubbed the ‘Vaccine for the World’. We think this is a fair label,” he wrote. “Data like this, reported today to be more conclusive about the effectiveness and safety of AZD1222, is certainly cause for celebration.”

AstraZeneca has committed to distribute the vaccine for the duration of the pandemic for no profit. The company’s shares traded 2% higher in London on Monday.