Ox Xford vaccine shots that work better in smaller doses raise questions

Ox Xford vaccine shots that work better in smaller doses raise questions

Coronavirus vaccine: AstraZeneca and Oxford are conducting vaccine trials in different parts of the world.


  • AstraZeneca, Ox Xford are conducting trials in different parts of the world
  • The Oxford team is still analyzing the data to better understand how the vaccine works
  • Only two doses of the vaccine are available in the U.S. Is a part of the study

The news reached Sarah Gilbert on Saturday evening that she appeared to be working with AstraZeneca PLC to develop the Covid-19 vaccine. But the Oxford University professor expected a key number: was it less effective than the others – or less than 90% effective?

Instead, when his colleague Rew Andrew Pollard called with the result, he wanted to show his slides instead of simple ones. “I didn’t really understand why we had to go through the slides,” she recalled. “But then it became clear – because it’s more complicated in our trial.”

That complexity leads to uncertainty for one of the front runners swirling around with Race Pfizer Inc. and Moderna Inc. to end the one-shot epidemic. Questions about the most effective dosage of the vaccine, its safety record, and partners’ approach to its testing have been raised in the U.S. The Food and Drug Administration has expressed doubts about whether it will clean up.

Earlier Monday, AstraZeneca and Ox Xford reported results after 131 trial participants in the UK and Brazil signed with Kovid 19. In the expectations of analysts and the FDAA set an average of 70% prevention effectiveness for the covid vaccine set by the 50% standard.

According to Monsef Sloui, a former GlaxoSmithKline PLC researcher who heads the U.S. Operation Operation Speed ​​Program, the study also found 16 serious cases, all of which were among those who did not receive AstraZeneca shots. That was good news for Astra’s vaccine program, which was launched in the U.S. Was suspended for six weeks when regulators reviewed a serious adverse event, about which the company never provided details. Oxford will provide details of the adverse events in its effectiveness study which it will submit for review next week.

The surprising part about Astra’s results is that large doses were less effective. The vaccine was only 62% effective in the group that received two full doses except for about a month. But of the approximately 2,700 people who received half the full amount, it increased to 90%.

Positive data on other vaccines of significant efficacy with potential benefits of storage, transportation, and affordability will be welcomed, said Jesse Goodman, former head of the FDA’s vaccine office, who later became the agency’s chief scientist.

“What is not clear yet is whether this effect is an opportunity observation or does it reflect something that overdoing adversely affects the immune response,” he said in an interview. “We need more details to understand that.”

SVB Analyst with Lyrink, J or Frey Porges, was among the most critical voices, calling the data “premature and inadequate” in a note to customers and predicting that the vaccine would “never be licensed in the US”, with shares in London up 3.8%. Were reduced.

Be patient

AstraZeneca and Ox Xford are conducting vaccine tests in various parts of the world and are currently in the U.S. The study is studying only two doses of the vaccine in which 30,000 volunteers are expected to enroll. Rud Dobre, executive vice president and president of biopharmaceuticals at AstraZeneca, said the company was still recruiting participants and could add another hand to further study the transaction with the help of half a dose.

“Let’s be a little more patient and see how the FDA reacts before making such harsh statements,” he said in an interview with Bloomberg TV.

The UK’s Medicines and Healthcare Products Regulatory Agency has begun its analysis based on data obtained in the Rolling Review, chief executive June Raine said in a statement. Soumya Swaminath, two leading scientists, said that the low efficacy of the two full-dose regimens also hit the World Health Organization’s benchmark. Low- and middle-income countries are turning their attention to shots at much lower prices than Pfizer and Modern as a way out of this epidemic.

But low doses that give better results cause many people to scratch their heads, including Gilbert himself. To increase effectiveness, Gilbert said, researchers tested to find the lowest dose of the regimen with the initial half dose, which can still produce a strong immune response.


“I was surprised,” he said in an interview. “I didn’t really expect that.”

Excellence from its full two doses can be good news, allowing the company to inoculate more than the same overall amount of vaccine. That could be significant with the need to vaccinate billions of people around the world.

The vaccine uses a harmless chimpanzee adenovirus – the cause of some common colds – as a vector that is then inserted with the coronavirus spike protein to produce an immune response.

Theoretical reasons

It is theoretically possible that the full initial dose produces antibodies in the adenovirus vector, which may limit the immune response to the coronavirus spike protein, Gilbert said. But his team measured ad dinovirus antibodies in previous studies and found only a slight effect.

“I’m not sure if that’s the perfect answer. We’ll look into that further.” “But it can be somewhat subtle in terms of providing high-quality immunity by simply giving the vaccine the right amount of antigen at the first dose and then extending it to the second dose.”

A possible explanation for the different outcomes is that lower initial doses work better to pass through the body’s defenses, which infect vaccine cells and produce an immune response, said Michael Kinch, a drug development expert and associate vice chancellor in Washington. University in St. Louis.

The second theoretical reason is more complex: the immune system may be injured by the initial high dose of the vaccine and ignore the subsequent dose, an event known as tolerance or immune desensitization. Either way the effects of a single shot are likely to be untouched.

“The 90% headline number may eventually prove right,” Kinch said, “but the dose response inversion could be a sign of concern.”

The Ox Xford team is still analyzing its data to better understand how the vaccine works. Gilbert said she is confident the high efficiency numbers will catch on when more data comes out.

“It could go down a little bit or a little bit,” he said. “I don’t think it’s going to change that much, but when we do a little bigger analysis it could turn in both directions from the initial 90%.”

(Except for the headline, this story has not been edited by NDTV staff and has been published from Syndicate Feed.)