Oxford AstraZeneca Vaccine Effective But Questions Remain for Elderly

A vaccine developed by the University of Oxford and AstraZeneca Plc provided protection against severe Covid-19, a peer-reviewed study showed, though more analysis will be needed to see how well it works in older people, among those at highest risk in the pandemic.

The 10 cases of hospitalization seen in the trial all occurred among those given a placebo, suggesting the shot prevents the worst symptoms, according to the results published Tuesday in The Lancet medical journal. Yet the vaccine’s efficacy couldn’t be assessed in older age groups because there weren’t enough infections, the data show.

Because older adults were recruited to the studies later than younger ones, “they’ve had less time for cases to accrue in those age groups and for us to be able to measure an efficacy signal,” said Andrew Pollard, director of the Oxford Vaccine Group. “The evidence we have so far on the immune response very much suggests that it’s likely to be similar levels of protection across the ages.”

The report sheds more light on the strengths and shortcomings of the inoculation following weeks of confusion surrounding the late-stage trial, but still leaves unanswered questions about its potential role fighting a contagion that has killed more than 1.5 million people. Still, even if the vaccine can’t match the efficacy delivered by front-runners Pfizer Inc. and Moderna Inc., it is expected to be cheaper and easier to deploy far and wide.

The Lancet report provides the first peer-reviewed data from any of the front-runner vaccines.

Initial data from Astra and Oxford last month appeared positive but raised concern over how much protection the shot would offer after the trials produced two different results from two dosing regimens. The partners said their vaccine was 90% effective when a half-dose was given before a full-dose booster, and that two full doses showed an efficacy of 62%.

It later emerged the lower dose was the result of a manufacturing discrepancy and only tested in a younger group. Astra CEO Pascal Soriot said in an interview last month the company would set up an additional, probably global, trial to verify the 90% result. The company said Tuesday it’s still deciding whether to hold an additional study.

The viral vector vaccine uses a harmless virus to transport genetic material which triggers an immune response to the coronavirus

The results, based on advanced trials of 11,636 people in the U.K. and Brazil, were reviewed after 131 participants contracted Covid-19. Of those, 30 were in the group that received the vaccine and 101 in the control arm, equating to an efficacy rate of 70%, according to The Lancet data.

While the vast majority of 175 severe adverse events were deemed unrelated to Covid-19 or control vaccines, one case of the neurological disorder transverse myelitis may be linked to the shot, the paper said.

Astra shares rose as much as 1.3% following the release of the Lancet report, and were up 0.7% at 4:09 p.m. in London trading.

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